QC 995 TORNADO .1155 1973 c.2 PREPAREDNESS F PLANNING

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U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Weather Service oc .a& ih73 cZ TORNADO MESS PLANNING

LIBRARY

JAN 282014 National Oceanic & Atmospheric Administration 1 U- " -me-ca I

U.S. DEPARTMENT OF COMMERCE Frederick B. Dent, Secretary John K. Tabor, Under Secretary

F NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION Robert M. White, Administrator

NATIONAL WEATHER SERVICE George P. Cressman, Director

OCTOBER 1973

F NOAA/PA 70009 (Rev. 1973) For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402- Price 65 cents Stock Number 0317-00215 PREFACE

In June 1973, the Defense Civil Preparedness Agency (DCPA) and the National Oceanic and Atmospheric Administration (NOAA) signed an agreement to coordinate the community natural disaster program. It designates the DCPA On-Site Assistance program as the means for carrying out much of the disaster preparedness planning effort at the local government level. We believe this agree­ ment will lead to improved coordination in community disaster planning through­ out the Nation. The DCPA, state Civil Defense, and the National Weather Service (NWS) of NOAA have been cooperating in planning and coordinating community pre­ paredness meetings and drills. This agreement will provide a better organized and more systematic effort by both agencies. The tornado preparedness planning information in this pamphlet is to aid the local lpaders and the On-Site Assistance teams in developing community preparedness plans. These plans are needed (1 ) to ensure coordinated action by everyone involved (c.g., warning agencies, local officials, law enforcement agen­ cies, cooperating news media, rescue and medical agencies, disaster relief agencies, and volunteer communications groups); (2) to ensure the adoption and imple­ mentation of proven practices and procedures; and (3) to carry out a public education program concerning the threat of tornadoes and severe thunderstorms and the measures that individuals should take to safeguard themselves when they are in the path of these devastating natural hazards. Community tornado preparedness plans should be commensurate with the frequency of such storms, the population density, and the resources of the community. George P. Cressman Director, National Weather Service CONTENTS

Chapter page Preface ...... iii I Introduction ...... 1 What Can Be Done...... i How to Start Doing It...... 1 II Tornado Preparedness Planning ...... 3 National Weather Service Cooperation ...... 3 The First Meeting ...... 3 The Tornado Preparedness Committee ...... 4 III Building Blocks for a Tornado Preparedness Plan...... 5 The Published Plan ...... 5 Example of Section 5 Contents...... 6 IV Tornado and Severe Thunderstorm Reporting Networks...... 8 Establishment of Networks ...... 8 Training of Spotters ...... 9 Operation of the Spotter Network...... 9 Appreciation of the Spotters’ Efforts...... 10 Practice Drills ...... 10 Special Supplemental Spotters ...... 10 V Communications and Distribution of Warnings ...... 11 Necessary Internal Communications Arrangements...... 11 Reaching the Public ...... 1 ] Reaching the Broadcast Stations ...... 12 Other Means ...... 12 Audible Warnings ...... 13 VI Public Education on Tornadoes and Severe Thunderstorms...... 14 Recommended Safety Rules and Pre-Season Actions...... 15 Special Safety Rules and Pre-Season Actions for Schools...... 16 Lightning Safety Rules ...... 16 VII Medical and Hospital Tornado and Severe Thunderstorm Plains...... 18 VIII Post-Disaster Relief and Rehabilitation ...... 19 IX Severe Local Storm Warning Service...... 20 X Description and Climatology of Tornadoes and Severe Thunderstorms...... 24 Characteristics of Tornadoes ...... 24 The Work of Winds and Pressure ...... 25 Wind Speeds ...... 25 The Casualty and Damage Potential ...... 25 Major Tornadoes...... 26 Characteristics of Severe Thunderstorms...... 26

List of Illustrations Figure L Tornado Incidence by State and Area, 1953-1971 ...... 26 2. Deaths From Tornadoes, 1953-1971 ...... 27 3. Threat Rating From Tornadoes, 1953-1969 ...... 27 4. Tornado Incidence by Month, 1953-1971 ...... 28

List of Tables Table 1. Guide for Contact with National Weather Service Regional Headquarters ...... 2 2. Suggested Attendance for a Tornado Preparedness Planning Meeting...... 4

IV CHAPTER I—INTRODUCTION

Your wife is in the kitchen, preparing the evening ards and how to protect themselves. This education meal. Your children are playing outdoors. should be arranged by the local leadership as part of The broadcast program is suddenly interrupted. tornado preparedness planning. This leadership can The announcer says, urgently: “The U.S. Com­ also fit tornado preparedness planning to the re­ merce Department’s National Weather Service has sources and capabilities of the comunity. just issued the following Tornado Warning Bulletin” What Can Be Done? A “TORNADO WARNING IS IN EFFECT UNTIL 7 P.M. FOR PERSONS IN [YOUR A Tornado Preparedness Plan can be developed to COUNTY], A TORNADO WAS SIGHTED fit any size community, from a small town to a large SIX MILES SOUTHWEST OF [YOUR metropolitan area. Plans are needed even for com­ TOWN] AT 5:15 P.M. THIS TORNADO IS munities where no tornado has ever struck. Every MOVING TOWARD THE NORTHEAST AT year, places that have never been struck before join TWENTY MILES PER HOUR. IF A TOR­ the list of tornado disaster locations. NADO OR THREATENING CONDITIONS Can anything really be done to minimize a tor­ ARE SIGHTED ... BE PREPARED TO nado disaster? Yes—by public education in the ap­ MOVE TO A PLACE OF SAFETY.” plication of effective procedures, timely wide-spread warnings can be applied to save many people from What does this mean to your wife? What should death or injury when a tornado strikes. The same she do to protect herself and the children? Has she system can be used to spread the word when severe ever been told what shelter to seek, or how to recog­ thunderstorms pass over an area, in order to reduce nize an approaching tornado? Has your community deaths and injuries from lightning, high winds, and developed plans for warning her neighborhood—for destructive hail. recommending shelter areas—for quick rescue opera­ Although a community may have a disaster plan tion if a tornado strikes? for other hazards (man-made or natural), tornadoes If your community is among those which have and severe thunderstorms are “short-fuse” hazards developed tornado preparedness plans, your wife and and can strike suddenly, then move quickly across an children will have a much better chance of survival area. Special cooperative arrangements need to be and rescue if your neighborhood, or even your house, made to watch for them, detect them as soon as is struck. possible, and quickly warn the areas in the path of If, however, your community is among those their movement, so that people can go to proper which have not yet developed and established a Tor­ shelter immediately. Preplanned rescue and relief op­ nado Preparedness Plan, the development of an ade­ erations should be ready to start as soon as disaster quate plan should be considered seriously—NOW. strikes. This pamphlet gives you information on what can be done and how to do it. How to Start Doing It The potential for loss of life and property from tornadoes increases year by year. As open fields be­ NOAA’s National Weather Service (formerly the come residential areas, the target for disaster broad­ Weather Bureau) started its severe local storm fore­ ens. New people move into the community, often cast and warning service in 1953. Since then, with unaware of what can happen. Old and new residents improved techniques and communications—with ex­ and education concerning the threat of natural haz­ panded and intensified cooperation from the news

1 media and from authorities in charge of public pro­ States in Southern Region: tection, rescue, and relief—and with the valued help Alabama Mississippi of individuals who watch for tornadoes and severe Arkansas New Mexico Florida Oklahoma thunderstorms and make quick reports to area offices Georgia Tennessee of the National Weather Service—the average num­ Louisiana Texas ber of deaths and injuries from these hazards has de­ Address: Director, Southern Region creased considerably. National Weather Service, NOAA 819 Taylor Street Each National Weather Service office in the Fort Worth, Texas 76102 United States has been assigned the responsibility for Telephone: (Area Code 817) 334-2668 arranging for the distribution of watches and warn­ States in Central Region: ings of severe local storms, including tornadoes, Colorado Minnesota throughout a number of counties. Every county in Illinois Missouri the United States is served by an office of the Na­ Indiana Nebraska Iowa North Dakota tional Weather Service responsible for issuing perti­ Kansas South Dakota nent warnings to it. Kentucky Wisconsin Michigan Wyoming Table 1 lists by States the National Weather Serv­ Address: Director, Central Region ice Regional Headquarters which should be con­ National Weather Service, NOAA tacted, by mail or telephone, to find out which office 601 E. 12th Street should cooperate with your group of local authorities Kansas City, Mo. 64106 in developing your community’s tornado prepared­ Telephone: (Area Code 816) 374-7000 ness plan. They will be glad to arrange to have a States in Western Region: representative meet with you to discuss any points Arizona Nevada needing clarification. California Oregon Idaho Utah Act now! You may save residents of your com­ Montana Washington munity from death or injury this year—and for many Address: Director, Western Region National Weather Service. NOAA years to come. Box 11188, Federal Building 125 South State Street Salt Lake City, Utah 84111 Table 1—GUIDE FOR CONTACT WITH NA­ Telephone: (Area Code 801) 524-5500 TIONAL WEATHER SERVICE RE­ State of Alaska: GIONAL HEADQUARTERS Address: Director, Alaska Region National Weather Service, NOAA 632 6th Avenue States in Eastern Region: Anchorage, Alaska 99501 Connecticut North Carolina Telephone: 272-9522 Delaware Ohio Maine Pennsylvania State of Hawaii, and Pacific Possessions: Maryland Rhode Island Address: Director, Pacific Region Massachusetts South Carolina National Weather Service, NOAA New Hampshire Vermont Bethel-Pauahi Building New Jersey Virginia 1149 Bethel Street New York West Virginia Honolulu, Hawaii 96813 Address: Director, Eastern Region Telephone: (Area Code 808) 546-5680 National Weather Service, NOAA Public Information Office 585 Stewart Avenue National Oceanic and Atmospheric Administration Garden City, New York 11530 Rockville, Maryland 20852 Telephone: (Area Code 516) 248-2101 Telephone: (Area Code 301) 496-8243

2 CHAPTER II—TORNADO PREPAREDNESS PLANNING

Your community may be a metropolis, or a subur­ He can inform you of successful planning by other ban area, or a smaller city, or a town, or a farming communities. or ranching area. In most cases it does not have an And he can explain your part in distributing warn­ office of the National Weather Service located within ings and in arranging for public education on torna­ it. But in every case, a National Weather Service does and severe thunderstorms. office is responsible for providing alerting informa­ tion and for warning your community concerning The First Meeting severe local storms, including severe thunderstorms Table 2 shows suggested attendance for a Tornado and tornadoes. Preparedness Planning Meeting. From the experience Tornado preparedness planning consists of devel­ of communities of various sizes that have developed oping arrangements and communications between tornado preparedness plans, comprehensive represen­ the responsible warning agency and the local county, tation at the organizing meeting leads to maximum and state authorities and agencies responsible for cooperation and rapid development of the plan. public protection, safety, rescue, and relief—so that, The interested news media—newspapers, radio when necessary, the most appropriate immediate ac­ stations, and television stations—should be invited. tion can be taken. The planning covers the arrange­ The cooperating National Weather Service official ments designed to ensure concerted local action will assist by making background material available when the emergency arises. in advance. The responsibilities of agencies taking part in a National Weather Service Cooperation community warning system are:

Tornado Preparedness Planning adjusts this Basic WARNING AGENCY LOCAL AGENCIES Warning System to the size, needs, and resources of (NATIONAL WEATHER 1. Alert personnel when "Watch" is issued and your particular community. It is here that your coop­ SERVICE) 1. Constantly collects re­ help disseminate erating National Weather Service official enters into ports. Closely follows Watches, Warnings, se­ the picture. He will explain in full detail the concept weather conditions. vere weather statements of a Tornado Preparedness Plan to fit your commun­ 2. Assesses severe weather and All-Clears. ity. He can do this best in a meeting. potential. 2. Assist in reporting occur­ 3. Issues "Watch" bulletins rences of severe weather. He knows your community’s severe local storm and severe weather state­ 3. If severe local storm climatology. ments. threatens community, sound local warning im­ He can tell you how the National Weather Service 4. If severe weather is sighted or indicated, is­ mediately. provides severe local storm watches, warnings, prog­ sues "Warning" bulletins. 4. Act to protect, rescue, ress statements, and all-clear bulletins. 5. Monitors for additional and relieve public during and after disaster. He can advise you how to organize spotter net­ threats; continues severe weather statements; and 5. Feed back information works and communications for quick detection and issues new warnings when on occurrences to warn­ reporting of the formation and approach of torna­ necessary. ing agency. does and severe thunderstorms. 6. Issues All-Clear bulletins.

3 Table 2—SUGGESTED ATTENDANCE FOR A Tornado Preparedness Plan. These people will need TORNADO PREPAREDNESS PLAN­ a focal point—a standing Tornado Preparedness NING MEETING Committee—to decide upon the coordination of the NOTE: Selections from this list will vary according to the various parts of the Plan, and to oversee and en­ size, location and geography of the community, etc. In some sure its implementation and continuing operation. cases more than one official of each category should be in­ vited (e.g., when more than one jurisdiction is involved). The cooperating National Weather Service official Community Head or Heads (Mayor, Manager, Chairman of will be available to help in the Committee’s work. Board of Supervisors, President of Council, etc.) I he Tornado Preparedness Committee’s member­ Newspapers serving community ship should comprise representatives of the vital Radio and Television Stations serving community (including agencies of the community or area. Subcommittees those serving from outside the community) Community Police Head (to work out the general ideas of the full committee) Community Civil Defense Director should be formed to work out the following parts of County Civil Defense Director the plan: Appropriate Red Cross Chapter Chairman, Disaster Chair­ Spotter Networks (see Chapter IV) man, and Disaster Service Representative Communications Networks and Warning Dis­ County Law Enforcement Head District or Area State Law Enforcement Agency semination (see Chapter V) Medical Association Public Education on Tornadoes and Severe Hospital Heads Thunderstorms (see Chapter VI) Superintendent of Public Schools Medical and Hospital (see Chapter VII) Heads of Private Schools and of Colleges and Universities Post-Disaster Relief and Rehabilitation (see Head of Fire Protection Agency Chapter VIII) Radio Amateurs, Citizens’ Band Radio Groups, Citizens' Radio Service When your Tornado Preparedness Plan is agreed State National Guard upon, the Committee should have it reproduced, dis­ District Engineer, U.S. Corps of Engineers tributed, and activated with appropriate, continuing Federal Communications Commission Regional Liaison publicity to ensure maximum awareness on the part Officer of the public and all participating agencies. FCC’s State Industry Advisory Committee and/or Area In­ dustry Advisory Committee Once the Tornado Preparedness Plan is in opera­ Public Utilities tion, the Tornado Preparedness Committee should Manager of Public Transit meet at least once a year, just before the beginning Community Engineering Department of the tornado season (usually by early February). It Superintendent of Streets and Public Works Civil Air Patrol should fill any vacancies in its membership; review Airport Manager the Plan and make any necessary changes; reac­ Federal Aviation Administration Representative quaint the members with the Plan, including fami­ Commanders of U.S. Military Facilities in or near Commu­ liarization of any new members; make plans for nity renewal of the public’s education on tornadoes and U.S. Coast Guard (where applicable) Consideration could also be given to inviting: severe thunderstorms; and make plans for practice Governor’s Representative (especially when more than one drills. It may also accomplish an important function State is involved) in case of disaster by holding a timely post-disaster State Director of Civil Defense review at a special meeting to determine the effec­ Regional Officer of the Office of Civil Defense tiveness of the action taken, and to make necessary Regional Officer of the Office of Emergency Preparedness changes in the Tornado Preparedness Plan to im­ Public Health Service, HEW, Representative Consumer and Marketing Service, Department of Agricul­ prove its application. ture, Representative Chapter III presents a building-block approach to General Services Administration Representative this planning that will make decisions easier. It also State Board of Education includes a summary treatment showing how all ele­ ments in the plan dovetail to provide a complete The Tornado Preparedness Committee warning system. Chapters IV, V and VI deal in The officials and representatives at the meeting will detail with those aspects of planning which might be know the resources available to them, and the gen­ termed “minimizing danger.” Information concerning eral disaster plans applicable to the community or medical and post-disaster procedures, Weather Bu­ area. They will know which people should be reau operations, and Severe Weather Climatology is brought together to develop the various parts of the outlined in the remaining Chapters.

4 CHAPTER III—BUILDING BLOCKS FOR A TORNADO PREPAREDNESS PLAN

Depending upon the size and complexity of a 10. Information on actions to be taken after a community or area, a Tornado Preparedness Plan disaster, and availability of food, shelter, may include arrangements from the simple to the medical supplies, water, fire prevention, elaborate. sanitation, and military assistance. The plan will also vary with the facilities available The Published Plan for dissemination of Watches and for quick local dissemination of Warnings (sirens, local broadcast Pertinent parts of the Tornado Preparedness Plan stations, etc.). that have been worked out by subcommittees and All plans have in common certain basic arrange­ approved by the Tornado Preparedness Committee ments: should be reflected briefly and clearly in a published pamphlet or brochure, which should be kept up-to- 1. Indication of the National Weather Service date by spot revisions during the severe storm season office responsible for Warnings. and by periodic revision. 2. A tornado and severe thunderstorm report­ Suggested contents are: ing network. Section 1—Specification of the community or area 3. One or more Warning Centers. to which the plan applies, and of the re­ 4. Communications for dissemination of sponsible National Weather Service office; Watch bulletins and Warning bulletins and and definition of “Tornado Watch,” “Tor­ for alerting safety, rescue, and relief agen­ nado Warning,” “Severe Thunderstorm cies. Watch,” “Severe Thunderstorm Warn­ 5. Provisions for alerting schools, factories, ing,” “Severe Weather Statement,” and and other places where people are ordinar­ “All-Clear Bulletin.” ily congregated, to the need to activate a Section 2—A chart and keyed list of tornado report­ supplemental watch on threatening weather ing network locations. conditions for their own immediate benefit. Section 3—Location(s) of Warning Center(s) and a 6. Provisions for alerting and warning people list of their personnel and alternates, to­ in outlying areas. gether with home and business telephones. 7. Specific, detailed provisions for action to be Section 4—List of communication channels for: taken when a tornado or severe thunder­ —Transmitting severe weather spotters’ storm strikes. reports of sightings to Warning Cen- 8. Warning lists, and rosters of key personnel ter(s) and to the National Weather and alternates. Service; 9. Brief, clear reference information on steps —Dissemination of Watch bulletins (in­ that should be taken by the public to be cluding local and non-local radio and prepared for tornado and severe thunder­ television stations serving the area, and storm strikes—such as the best places to hours of operation); take shelter, plans for the safety of school —Dissemination of Warnings, Severe children, and availability of battery-oper­ Weather Statements, and All-Clear ated radios. bulletins;

5 —Alerting special meetings, sports events, storm Watch is announced for the community or and other non-routine gatherings of the area to which the Tornado Preparedness Plan ap­ public; plies: —Alerting and warning people in out­ 1. All concerned with dissemination of lying areas; Watches and Warnings should carefully ad­ —Alerting local authorities, when a here to the term “Watch” when only a Watch is issued, and for informing Watch applies and use the term “Warning” them immediately when a Warning is only when a Warning has actually been is­ issued; sued. The exact wording of each bulletin —Alerting school systems, factories, and should be used, to ensure that its meaning is other points involving routine congre­ maintained. gation of people; and 2. The tornado reporting network should be —Alerting and warning law enforcement activated (according to pre-planned proce­ agencies, hospitals, rescue and medical dures). Spotters hearing the Watch broad­ personnel, and relief agencies. cast will commence their watch immedi­ Section 5—Sequence of actions to be taken by the ately. warning, law enforcement, medical, and 3. Law enforcement reserve personnel should rescue agencies when a tornado or severe be called to duty or alerted by law enforce­ thunderstorm approaches or is occurring ment heads. in the area (step-by-step, from the spot­ 4. If in session, all schools should be notified ter’s report to the sounding of sirens or by the school headquarters of the com­ other local immediate warning, and on mencement of a Watch, and their supple­ to the end of the threat). (See example, mental severe weather spotters should be below.) alerted to commence a watch for severe Section 6—List of immediate post-disaster actions— weather conditions. prevention and control of fires, turning 5. Supplemental severe weather spotters for off of electricity and gas in damaged areas factories, sports events, etc., should be (listing those responsible for acting, with alerted to commence watch. alternates, and how to contact them), pro­ 6. The Watch should be distributed over all vision of emergency power and communi­ communications channels participating in cations facilities, plan for emergency shel­ the Tornado Preparedness Plan. ters, transportation and feeding, location 7. All Fire Department stations should be of medical supplies and water supplies, alerted and notified of the Watch by Fire and measures for prevention of disease. Department headquarters. Section 7—Brief guidance on how to obtain emer­ 8. Hospitals, medical personnel, and nursing gency support from other communities or and rest homes should be alerted, and the military when the usual local resources should place their plans in effect. have proved inadequate to handle the 9. Warning Centers will determine the rela­ emergency; and how to obtain longer- tionship of their local areas to the area an­ term rehabilitation assistance from State nounced (in terms of counties, cities, or and Federal sources. geographical boundaries) as covered by the Section 8—Roster of Tornado and Severe Thunder­ Watch, and if in or near the Watch area, storm Reporting Network spotters by sta­ will alert (others, as arranged in the Plan). tions, with their telephone numbers; of 10. Mobile radio-equipped severe weather spot­ key amateur radio personnel, with their ters (as arranged in the Plan) will proceed telephone numbers, call-letters, and fre­ to (designated points), and watch for torna­ quencies; and of other key personnel, and does or severe thunderstorms. Sightings will alternates, for ready reference. be reported by (communications channels arranged) to Warning Center(s) and to the Example of Section 5 Contents National Weather Service office. When a tornado or a severe thunderstorm is de­ When a Tornado Watch or a Severe Thunder­ tected:

6 1. Tornado and Severe Thunderstorm Report­ the area in the direction of the storm’s path, ing Network spotters—Report sighting first will be alerted by (Tornado Preparedness to Warning Center of community immedi­ Plan arrangements), and will warn occu­ ately in path of storm; second, by COL­ pants of the facility to take cover if the LECT telephone call to National Weather tornado or severe thunderstorm approaches. Service office, telephone number...... 5. Warning Centers, law enforcement agencies, (as given to Network members); or to the and others receiving Warning and in posi­ nearest law enforcement agency if the Na­ tion to do so, warn public directly (by si­ tional Weather Service office cannot be rens) (specify who activates), warn resi­ reached. Law enforcement personnel in dents of rural areas, etc. Law enforcement contact with (law enforcement center) re­ officers on the street warn the public to take port sightings to dispatcher over (channel); shelter. dispatcher report sightings to National 6. Emergency broadcasts of Warning bulle­ Weather Service office by (communications tins and severe weather statements by co­ channel arranged). operating broadcast stations provide warn­ 2. Local Warning Center sounds local alarm ing and indication of endangered locations, (sirens, bells, or other means arranged); direction of tornado or storm movement, and confirms sighting to National Weather and brief advice on actions individuals Service office by (communications channel should take for self-protection. arranged). 7. Rescue and relief agencies, alerted by spe­ 3. National Weather Service office verifies lo­ cial National Weather Service messages or cation, determines direction of storm move­ by the broadcasts, prepare to proceed im­ ment, and issues Tornado Warning, or Se­ mediately to stricken area, as reported by vere Thunderstorm Warning to radio and law enforcement agencies or others. television stations by (communications 8. National Weather Service office issues fre­ channels arranged); and makes other distri­ quent Severe Weather Statements, reiterat­ bution as follows: (per Tornado Prepared­ ing Warnings, and issues Warnings for new ness Plan arrangements) to Warning Cen­ areas as appropriate, as the storm condition ters) concerned; to law enforcement agen­ moves on or as new tornadoes or severe cies; and to others on National Weather thunderstorms form. Service office’s emergency warning lists. 9. National Weather Service office issues All- 4. Supplemental Tornado and Severe Thunder­ Clear bulletins for successive areas as the storm Watchers at schools, factories, etc., in threat ends.

7 CHAPTER IV—TORNADO AND SEVERE THUNDERSTORM REPORTING NETWORKS

Any person who has experienced the horror of The National Weather Service receives help from seeing an ominous funnel suddenly appear from a nearly 500 local SKYWARN networks but many thundercloud knows that a quick warning is necessary more are needed. Nationwide, these networks are to save those in the path of a tornado. Tornadoes and made up of thousands of public-spirited citizens and severe thunderstorms are not always preceded by the organizations. issuance of Tornado Watches or Severe Thunder­ Each network is organized around the needs of the storm Watches, because forecasting has not yet been area being served, with special consideration given to developed to that point, although much research con­ localities that are highly industrialized or heavily tinues to improve the techniques. Immediate Warn­ populated. In areas ol the United States where severe ings, based on reports of actual sightings, are of the local storms occur infrequently, such as the Far utmost importance. West, networks may be confined to interested groups Watches are not Warnings. such as State highway patrol and utility companies. The Watch tells people to go about their business, But in the parts of the country subjected to frequent but to keep an eye on the sky and in touch with severe local storms—tornadoes and severe thunder­ weather statements and Warnings issued by the Na­ storms—networks should be located throughout all tional Weather Service. Watches are distributed to counties in the area of responsibility of a National the public with the cooperation of the broadcast Weather Service office. Spotters should be spaced media. closely enough to be able to detect all severe local The Warning tells people of an actual sighting or storms, including those that occur during periods of an indication by radar and urges those in the danger reduced visibility caused by rain or darkness. path to prepare to take immediate cover for protec­ Ideally, trained spotters should be stationed at tion against death or injury if the hazard is seen points about two miles apart within a radius of about approaching them. 20 miles around a major population center. Heaviest The Watch alerts law enforcement, rescue, and concentrations of spotters usually should be to the medical agencies. The Warning sets them in motion southwest. An exception to this type of distribution to rescue the injured at the earliest moment and to would be a more uniform deployment around major provide them with medical attention. coastal population centers in southeastern States Even though a Watch may not have been issued, a which are threatened mostly by tornadoes associated tornado or severe thunderstorm sighting report can with hurricanes. Such tornadoes may approach from set in motion a Warning to communities in the path an easterly direction. of a hazard in time for people to take cover, and Residents of several towns may form a mutual shorten the time required for implementing post-disa- network, which may help to serve several towns as ter rescue and relief measures. Until techniques and well as a nearby city, or in some cases cover an equipment are developed to detect the early forma­ entire county or even a group of counties. tion of all severe weather hazards, successful detec­ tion of tornadoes and severe thunderstorms will re­ quire the support of a dense network of storm re­ Establishment of Networks porters—“spotters”—and effective, quick reporting A thorough survey should be made of networks procedures. that have been established for other purposes. These

8 may include radio amateur leagues, State and county Training of Spotters Civil Defense units, multi-county fire departments, All SKYWARN spotters and reports are supplied public utilities companies, industrial security groups, with detailed instructional material by the National State, county, and local law enforcement agencies, Weather Service. Included are copies of the bro­ and highway departments. These groups are trained chure, “Tornado,” “Tornado Safety Rules,” “Spot­ to react capably to emergency situations and many ter’s Guide for Identifying and Reporting Severe have communications facilities for rapid reporting. Local Storms,” and “Severe Local Storm Warning Meetings should be arranged between the heads of Service (and Tornado Statistics 1953-1969).” Spot­ these groups, their Communications Officer, the Tor­ ters should have a thorough knowledge of tornado nado Preparedness Committee, and the cooperating and severe thunderstorm characteristics, not only to National Weather Service official. The latter will ex­ ensure that they are able to recognize these hazards, plain the type of network needed and will request but also to avoid erroneously reporting non-hazard- cooperation and participation in selecting and train­ ous conditions and thereby generating needless warn­ ing spotters, and in developing and maintaining ings. efficient procedures for storm reporting and Watch Illustrations in these brochures and information and Warning dissemination. on the characteristics of severe thunderstorms and The law enforcement agencies, with their two-way tornadoes that appear in Chapter X of this pamphlet communications facilities and mobility, are very will assist in training spotters to make proper recog­ effective in spotter networks. They can disseminate nition of severe weather conditions. Watch bulletins, maintain a lookout for severe local The National Weather Service also provides spot­ storms, investigate rumored severe thunderstorms ters with an instruction sheet, “Spotter Procedures and tornadoes, activate local warning systems, and for Reporting Severe Local Storms.” The name and disseminate warnings. They can also quickly report telephone number of the National Weather Service disasters and direct rescue agencies to points needed. office to be called COLLECT when a tornado or Citizens’ Band radio groups have been very coop­ severe thunderstorm is observed are filled in on the erative in participating in the severe weather report­ bottom of the instruction sheet. If feasible, an alter­ ing networks. With their equipment, including mobile nate office and number are also supplied in the event equipment safe from power outage, they can fan out that the spotter has difficulty reaching the primary quickly and report immediately when a tornado or office by telephone. In addition each spotter is fur­ severe thunderstorm is spotted, through a key opera­ nished with a wallet-sized card containing the tele­ tor acting as filter between them and the responsible phone numbers to be called, in case he is away from National Weather Service office. The interest and his usual location when he sights severe weather. In enthusiasm of these groups is very high and their most instances, telephone numbers for reporting se­ cooperation is very helpful. Other amateur radio vere weather are unpublished, in order to keep this groups have performed many sterling services in time vital channel free for emergency reports. of disaster to aid the stricken public. Training programs should be developed locally to There is a need for supplemental severe local ensure efficient operation of a Tornado Preparedness storm spotters for schools, industrial plants, and Plan. The cooperating National Weather Service large gatherings of people such as fairs or sports official can assist with advice or in person, using events during threatening weather conditions, or training aids, as time permits. It is especially impor­ when the National Weather Service has issued a Tor­ tant that principals of all schools understand the Se­ nado Watch or a Severe Thunderstorm Watch for vere Local Storms Warning Service, and the value of the area. They should watch for storm development supplemental spotters for schools, together with and approach, and report to someone inside when well-planned and practiced procedures and a special the school, factory, or gathering is threatened, so that alarm signal for having school occupants take the a “take cover” alarm can be sounded. best available cover when the school’s spotter gives News media generally are glad to cooperate with a warning. Tornado Preparedness Committee by informing the public of the need for spotters. This often brings Operation of the Spotter Network forth the right type of well-motivated private volun­ Spotters are alerted to the possibility of dangerous teers. weather by the tornado and severe thunderstorm

9 Watches issued by the National Weather Service. Appreciation of Spotters’ Efforts Notification is by radio and television, law enforce­ The services performed by SKYWARN spotters ment networks, or other designated channels. When have saved many lives. The National Weather Serv­ a Watch is in effect, spotters should keep on the alert ice attempts to acknowledge their performance by to notify the National Weather Service office or the personal letters of thanks at the end of each season. Community Warning Center as soon as a tornado or Tornado Preparedness Committees may find that severe thunderstorm is sighted, describing the type of high morale can be maintained if a periodic newslet­ storm, its location, intensity, and direction of move­ ter is prepared under its auspices, and circulated to ment. Even though a Watch has not been issued, the members of the spotter network who are helping spotters have to be constantly vigilant for severe to protect the local community or area. The newslet­ weather whenever skies look threatening. ter could contain discussions on instructions, ques­ Each spotter who operates at a fixed point—home tions and answers in reporting procedures, and sum­ or office—is identified by a place name and a code maries of recent severe local storm activity, listing number by the National Weather Service office to those spotters who participated in reporting severe which he reports, for use as identification when call­ weather conditions. ing in. The place name assigned to the observing point is usually that of the nearest community or Practice Drills some prominent geographic location. Mobile spotters such as law enforcement personnel or amateur radio To make certain that the Tornado and Severe operators with mobile equipment, indicate their posi­ Thunderstorm Reporting Network becomes, or re­ tion and the location of the observed tornado or mains, functional, the Tornado Preparedness Com­ severe thunderstorm by reference to a town, a cross­ mittee should arrange for test exercises to be con­ road, or some other well-identified point. ducted during “safe” periods. All participants, the The National Weather Service office receiving the communications media, and the general public should spotters’ reports plots them, usually on its radar be notified in advance of the practice nature of the screen, which enables the radar operator to relate the exercise, so that there can be no confusion with an reports to the radar “echoes” produced by the clouds actual severe weather situation. Whenever possible, accompanying the severe weather. By this means, the such drills should be held at times other than the National Weather Service office can quickly deter­ usual storm season. mine the direction and rate of movement of the tor­ nado or severe thunderstorm threat; call other Special Supplemental Spotters spotters for confirming information; and deter­ Mobile home groupings and suburban shopping mine which areas should be given immediate warn­ centers can be particularly vulnerable to damage and ing. This system is also used to follow the further destruction from tornadoes and severe thunder­ progress of the storm cloud or clouds and to watch storms, and require special attention. To the extent for additional tornadoes or severe thunderstorms— possible, each should arrange for supplemental spot­ for sometimes more than one may plague an area at ters, identify a safe shelter, and train employees to the same time, and, unless reports are continued and use public address or other means to assist residents sorted out, confusion develops as to the location and or shoppers to reach this shelter when a tornado or a direction of movement of the threatening condition. severe thunderstorm approaches.

10 CHAPTER V—COMMUNICATIONS AND DISTRIBUTION OF WARNINGS

A comprehensive and reliable communications and Warnings to adjacent counties assigned to a Na­ system is essential for dissemination of Watches and tional Weather Service office, each county could be Warnings and for the exchange of information within assigned to an inter-county Warning Center. Inter­ the warning system. It should be a functional system, county Warning Centers, each responsible for four or based upon existing communications channels and five counties, are essential to a multi-county system. established on the principle of mass distribution Warning Centers located in county seats at Civil De­ through teletypewriter and radio communications. Its fense Warning Points and working closely with the purposes are to: National Weather Service would relay all messages a. provide the public with advance information to and from the counties assigned to those centers. that severe thunderstorms and tornadoes are Each county would have its own SKYWARN spotter likely; network and county Warning Center. Many of the b. provide progress reports concerning the devel­ communities in each county also would have their opment or lack of development of severe own warning systems. If a tornado were sighted, the weather; spotter would report the tornado to his county Warn­ c. arrange to receive severe local storm reports ing Center, then would call the responsible National from cooperative severe local storm observing Weather Service office. This procedure would allow and reporting networks; the county Warning Center to take appropriate d. distribute warning information to the areas to­ warning actions for the community or communities ward which the tornado or severe thunder­ immediately threatened, while providing the National storm is moving; Weather Service with the information needed to e. inform the public when the threat is over; and warn counties farther away but in the tornado’s path. f. provide backup communications. The county Warning Center would also send the report to the inter-county Warning Center over a Necessary Internal Communications Arrangements special civil defense telephone system, if available. In addition to Warnings, the National Weather Service A Warning Center is the focal point for the distri­ would furnish each inter-county Warning Center bution and receipt of severe weather information for with severe weather Watches and frequent informa­ a specified area via established communications. Se­ tion on any severe weather in or approaching the vere Thunderstorm and Tornado Watches and Warn­ counties assigned to the Center. At the county level, ings prepared by the National Weather Service are the county law enforcement agency would pass the distributed from this center. It also receives reports warning to designated officials in the county and in of approaching tornadoes and severe thunderstorms each city. from severe local storm spotters and issues local warnings. A local office of the National Weather Reaching the Public Service may act as the Warning Center but any other establishment which has adequate communications, Although the National Weather Service is respon­ standby power facilities, and remains open around sible for warning the public of the sighting of torna­ the clock would serve just as well. does and severe thunderstorms, it has limited means In order to expedite the dissemination of Watches of communicating Warnings directly to the public.

11 Instead, the National Weather Service relies on the and Warning responsibility, and the public is the public-spirited cooperation of the broadcast industry, broadcast industry which disseminates these Watches composed of the AM, FM and TV station facilities, and Warnings. as the primary method for reaching as large a part of the general public as possible with Watches and Reaching the Broadcast Stations Warnings of “short-fuse” hazards. Cooperation of the broadcast industry in this public service has been Until recent years, local and partial-State teletype­ uniformly excellent, and many people owe their lives writer circuits were operated by the National to it. Weather Service for warning purposes and to dissem­ Surveys show that under emergency conditions, inate weather information. In a number of States, when the interest and concern of the public have such facilities have been replaced by statewide, in­ been aroused, the broadcast industry has a potential trastate NOAA Weather Wire circiuts. The National listening and/or viewing audience of approximately Weather Service pays to have the circuits run to 90 percent of the population involved. every community of appreciable size in the State. However, it must be understood that participation Newspapers, radio and television stations, and others of the broadcast industry in spreading information on interested can have receivers on these circuits for a severe weather conditions for the benefit of listeners moderate connection and monthly service charge. and viewers is purely a matter of cooperation. Com­ These NOAA Weather Wire circuits have increased mercial broadcast stations (AM, FM, and TV) are the ability of the National Weather Service to trans­ not required by any government regulation to broad­ mit urgent Warnings to radio and television stations cast emergency weather Warnings. All weather serving communities in the path of any severe Warnings are transmitted at the option of the licen­ weather. In some States the National Weather Serv­ see, who maintains control of the station facilities at ice can activate positive alerting devices which call all times. the immediate attention of station personnel to the Broadcast arrangements across the country take urgency of the message so that it can be broadcast account of the greater transmissivity of radio waves immediately. Other Severe Weather Statements, de­ during nighttime hour. Most AM radio stations oper­ tailing the progress of the severe weather situation, ate only on a sunrise-to-sunset basis, going off the air continue to follow until an All-Clear bulletin from at local sunset. However, a nucleus of almost 500 the responsible National Weather Service official sig­ AM stations operates 24 hours daily. They have a nals an end to the threat. relatively large listening audience and should be in­ In States which do not yet have the NOAA vited to participate in any warning program of com­ Weather Wire (which is being implemented progres­ munities in the areas they serve. sively as funds become available) the local teletype­ In some cases, there are “hot lines”—direct voice writer loops continue to be a major means of quick connections—between the National Weather Service communication between the National Weather Serv­ office which originates warning, and the broadcast ice and the broadcast media and press wire service. studio, permitting National Weather Service officials The press wire services then relay important mes­ to broadcast directly (“live”) to the listening public. sages to their subscribers. In several areas, local broadcasters, with the encour­ agement of the Federal Communications Commis­ Other Means sion, have developed a plan whereby a key radio station alerts the other members of the system. The Besides the statewide teletypewriter circuits and member stations, all on a voluntary basis, rebroad­ the assistance of the broadcast industry, the National cast simultaneously the weather Warning that the key Weather Service uses a number of methods to trans­ station carries. Under present rules and practices em­ mit Warnings rapidly to key people at warning points ployed in the commercial broadcasting industry, it is in small communities. For example, a telephone call entirely a local and independent determination when may be made to other facilities capable of using their or whether to broadcast a natural disaster warning internal communications systems to relay Warnings to the listening public—and the cooperation has been to affected communities where sirens, loud speakers, excellent. and other means are employed to reach the public In summary, the primary link between the Na­ immediately. tional Weather Service office, which has the Watch Similarly, urgent messages are passed along to law

12 enforcement agencies (local, county, and State) and A steady-tone signal of three to five minutes dura­ Civil Defense units (frequently over a special Civil tion over Civil Defense sirens may be used, at local Defense-operated intrastate telephone network which option, as an attention-getting signal for natural dis­ connects Civil Defense Warning Points within each aster situations, or for other uses chosen locally. State). When this is used, persons should tune to radio and At a few locations (limited at present mostly to television stations to learn what and where the dan­ coastal points in the eastern and southeastern States) ger is. the National Weather Service operates a weather warning system by means of its continuous weather In rural communities, the party telephone some­ transmission facilities—on FM frequencies of times can be used to sound a general alarm. Church 162.40 and 162.55 MegaHertz. Individuals and bells and fire whistles are also available for sounding agencies having suitable receivers may obtain ade­ the alarm. quate warning of tornadoes or severe thunderstorms The American Red Cross participates in the public by this means. The equipment has a special tone- education program by making available through local emitting capability to activate suitably equipped chapters it’s color film “Tornado Disaster Action”, a muted radio receivers in schools, hospitals, govern­ four and one-half minute film issued in March 1968 ment offices, factories and other establishments within a transmitting range of about 50 miles (line which can be used by television stations in connec­ of sight). tion with tornado watch and severe thunderstorm For standby facilities, in case normal communica­ watch announcements. In addition the Red Cross tions are disrupted during a severe weather situation periodicially runs tornado safety material in it’s Red most National Weather Service offices depend on the Cross Youth magazine and cooperatively with cooperation of law enforcement agencies, civil de­ NOAA reproduces and distributes in quantity with fense, or amateur radio equipment, either backed by Red Cross imprint the various NOAA tornado safety emergency power generators or safe from disruption materials. This information is also made available to because of its mobile character. local Red Cross chapters for use in all kinds of publications, leaflets, and posters. The Red Cross Audible Warnings also, through it’s Disaster Preparedness Program, By the various means described National Weather works with all kinds of local organizations and local Service Watches and Warnings can be transmitted to offices of the National Weather Service to cooperate almost any point in an area of county responsibility. in tornado preparedness as well as other disaster There still remains the problem of warning people preparedness efforts. Information about the local directly who may not be listening to a broadcast but Red Cross disaster program can be obtained from me threatened by the immediate approach of severe local chapters and can easily be added to different weather. Warnings have been spread directly to the National Weather Service materials. In many in­ people on the street by individuals having access to stances the Red Cross will produce mailing enclo­ two-way mobile radios (amateur radio operators or sures for use in NOAA material and naming the Red law enforcement officers). They have frequently en­ Cross and the National Weather Service as it’s dangered their lives to do this. source.

13 CHAPTER VI—PUBLIC EDUCATION ON TORNADOES AND SEVERE THUNDERSTORMS

The National Weather Service of NOAA has bro­ range a program of repeated emphasis (with greatest chures, movies, and speakers to carry to the public concentration just prior to the tornado season) on its the message of the danger of tornadoes and severe Tornado Preparedness Plan and on the measures thunderstorms and what action to take when they that people should keep in mind for their personal threaten. The SKYWARN tornado preparedness safety. The mention of any imminent severe weather program, begun in January 1969, strengthens spotter in routine weather forecasts provides propitious recruitment, SKYWARN volunteers’ identity, and means to alert people who know how the Tornado public awarness of tornado hazards through publica­ Preparedness Plan works—how Watch bulletins and tions, articles, and institutional ads in cooperating Warning bulletins are disseminated, and what the newspapers. Prints of the color film “TORNADO!” safety rules are—to get ready to act if the need are available at moderate expense to school, librar­ arises. Since severe thunderstorms, which occur far ies, Civil Defense Offices, and others. National more frequently than tornadoes, are handled by this Weather Service officials will provide copies of the same Plan, the Tornado Preparedness Committee brochures at your Tornado Preparedness Meeting has the occasional opportunity to refresh the public’s and arrange for a showing of the film. Additional education, understanding, and safety practices be­ supplies of publications dealing with tornadoes and tween rare tornado occurrences. safety precautions are available for distribution at Recommended safety rules and pre-season actions, cost. Please apply to National Weather Service Re­ together with safety rules on lightning, appear at the gional Headquarters, or to the NOAA Public Infor­ end of this Chapter. mation Office, listed in Chapter I, Table 1, for in­ This program of repeated emphasis should aim at formation on how to obtain these aids. developing a public attitude of confidence in the Several years may pass, at times, without a threat local Tornado Preparedness Plan; informed caution to a particular locality. This results in public compla­ during periods of Tornado Watch or Severe Thun­ cency and apathy with regard to maintaining aware­ derstorm Watch; and, above all, readiness to be pre­ ness of safety measures to be taken during severe pared to take immediate cover for protection when­ weather outbreaks. Also, with our shifting popula­ ever a WARNING is issued. It should also stress the tion, newcomers to an area need education on severe characteristics and danger of severe weather hazards, local storms, on the warning system, and on shelter the terminology to be used to alert and warn the possibilities. public and where to obtain authentic information. Complacency may also increase if several Tornado or Severe Thunderstorm Watches have been issued With the advice of the cooperating National but the immediate local area does not experience Weather Service official, workshops and seminars severe weather. This is often the case. It is rare that should be arranged for local groups by the Tornado a particular Watch area is affected by severe weather Preparedness Committee. It is especially important over more than a small percentage of its area even that heads of various types of schools within the though the potential danger actually exists through­ area, and students as well, receive briefings on the out the area during the period of threat. importance of supplemental spotters for their build­ The Tornado Preparedness Committee (through ings, selection of shelter areas, distinctive severe the Subcommittee on Public Education) should ar­ weather warning signals within the buildings, and

14 drills to prepare for movement to safety areas when Tornado or Severe Thunderstorm Warning is issued. a tornado or severe thunderstorm approaches. Newspapers, radio stations, and television stations IMPORTANT: The effectiveness of any prepar­ have cooperated in arranging for articles and pro­ edness program depends upon the ability of all indi­ grams at the beginning of the local severe weather viduals to take immediate measures for their own seasons, stressing public education in protective mea­ protection. The Tornado Preparedness Committee sures against natural hazards and in using taped mes­ will find it beneficial to organize public participation sages (furnished by the National Weather Service) in off-season practice drills, fully announced well in following special announcements of Tornado and Se­ advance. Public and private schools, colleges, hospi­ vere Thunderstorm Watch and Warning Bulletins. tals, industrial plants, churches, sports arenas, and Interviews with Tornado Preparedness Committee other facilities for public assembly should conduct members and National Weather Service officials have practice sessions at least once each year. Schools also been presented. Newspaper publication of SKY- should have practice severe storm drills in much the WARN ads, safety rules, the meaning of the terms same manner as for practice fire drills. Distinctive “Watch,” “Warning,” and “All-Clear,” and the na­ tornado alarm signals should be used so people will ture of local Tornado Preparedness Plans has greatly know what to do or where to go when an actual increased public awareness in many communities.

RECOMMENDED SAFETY RULES AND PRE-SEASON ACTIONS \ Tornado Safety Rules In homes without basements Construction of a storm cel­ take cover in the smallest lar is particularly advisable room with stout walls, or for homes without base­ under heavy furniture, or a ments. An alternative is pre­ Shelter—Seek inside shelter PRE-SEASON ACTIONS tipped-over upholstered season selection of a nearby if possible. If in the open, couch or chair in the center culvert or deep ditch. move away from a tornado's part of the house. The first path at a right angle. If there floor is safer than the second is no time to escape, lie fiat (or third). If there is time, in the nearest depression, open windows partly on the such as a ditch or ravine. side away from the direction of the storm’s approach — but stay away from windows hi office buildings, the base­ Shelter areas should be se­ when the storm strikes. ment or an interior hallway lected and marked, and on a lower floor is safest. building employees should Mobile homes are particu­ If permission can be ob­ be trained to direct the oc­ Upper stories are unsafe. If larly vulnerable to overturn­ tained to use a nearby base­ there is no time to descend, cupants to them. ing and destruction during ment, a well-constructed util­ a closet or small room with strong winds, and should be ity building, or other nearby stout walls, or an inside hall­ abandoned in favor of a pre­ shelter, mobile-home park way will give some protec­ selected shelter, or even a occupants should select a tion against flying debris. ditch in the open. Damage leader responsible for ensur­ Otherwise, under heavy fur­ can be minimized by secur­ ing constant radio monitor­ niture must do. ing the trailer with cables ing and supplemental storm anchored in concrete foot­ spotting, and for sounding In homes with basements, A storm cellar, or a rein­ ing. the alarm if a storm ap­ seek refuge near the base­ forced portion of the base­ proaches. ment wall in the most shel­ ment can be planned and tered and deepest below constructed; or the safest Factories, auditoriums, and Shelter areas should be se­ ground part of the basement. portion of the basement can other large buildings with lected and marked, and Additional protection is af­ be selected and the family wide, free-span roofs, should building employees should forded by taking cover under drilled to use it. have preselected, marked be trained to direct occu­ heavy furniture or a work­ shelter areas in their base­ pants to them. Supplemental bench. Other basement pos­ ments, smaller rooms, or spotters should watch for sibilities are the smallest nearby. storms and give warning; room with stout walls, or drills should be held before under a stairway. and during season.

15 Personal preparations should Study safety rules, select Pre-season and periodic in-season severe include availability of a shelter area in home, provide weather drills should be held at all facilities to battery-operated radio, in extra batteries for small ensure that staff and students will all respond case of power loss; knowl­ radio, learn the siren or other edge of safety rules and how local immediate warning sig­ properly when an actual tornado or severe to tell if a tornado or severe nal for your community, and thunderstorm approaches the facility. thunderstorm is approach­ learn how to identify an ap­ Plans should be made to protect participants ing; and change of family proaching tornado or severe and those in group attendance at affairs such plans in order to remain thunderstorm. as sporting events (in gymnasiums or in the near shelter during a severe local storm threat. open) or school plays by reliable supplemental spotters, ample advance warning, and dis­ Parked cars are unsafe as missal with take-shelter instructions if any shelter during a tornado or severe windstorm; however, danger appears imminent. Gymnasiums and as a last resort, if no ravine auditoriums with wide-span roofs are unsafe in or ditch is nearby they may such situations. To the extent possible, plans provide some shfelter from should be made to shelter as many people as flying debris to those who possible in safe areas, such as in passage tun­ crawl under them. nels or under solid stands of playing fields, basements or inner hallways of buildings, and Special Safety Rules and Pre-Season Actions for otherwise as indicated under general safety Schools f rules. 1. The school system or group should develop a plan for internal dissemination of Watches and Lightning Safety Rules Warnings of tornadoes and severe thunder­ storms, based on assignment of a key person When indoors, and lightning threatens: and alternate(s) supplied with a communica­ 1. Stay indoors, and don’t venture outside unless tions channel or emergency telephone numbers absolutely necessary. to key persons in all facilities. 2. Stay away from open doors or windows, fire­ 2. All facilities should be inspected, and shelter places, radiators, stoves, metal pipes, sinks, areas selected and marked. and plug-in electrical equipment like radios, 3. Special “tornado alarm” signals should be es­ television sets, lamps, and refrigerators. tablished to warn all occupants of the facili­ 3. Don’t use plug-in electrical equipment like hair ties. A secondary system should be available driers, electric toothbrushes, or electric razors in case of power failure before a storm strikes. during an electrical storm. 4. A system of supplemental tornado/severe 4. Don’t use the telephone—lightning may strike thunderstorm spotters (teachers, administra­ the telephone lines outside. tive or maintenance employees, or reliable stu­ When outdoors, during a lightning storm: dents) should be established, ready for activa­ 1. Don’t work on fences, telephone or power tion whenever a Watch or Warning is an­ lines, pipelines, or structural steel fabrication. nounced or when severe weather conditions 2. Don’t use metal objects, like fishing rods and appear to be approaching the area. golf clubs. 5. Procedures should be established in each facil­ 3. Don’t handle flammable material in open con­ ity for monitoring of radio and television re­ tainers. ceivers for additional severe weather informa­ 4. Stop tractor work, especially when the tractor tion during threats. is pulling metal equipment. Dismount and 6. Procedures should be established for use or move away. Tractors in open fields are often non-use of school buses during conditions of struck by lightning. Watch and Warning; and drivers should be 5. Get out of the water and off small boats. Stay drilled in measures to be taken to provide for “indoors” in large boats. occupants to take cover in a shelter, ditch, or 6. Automobiles offer excellent lightning protec­ ravine if the bus is caught in the open by a tion, but they are unsafe places when a tor­ severe storm. nado or severe thunderstorm approaches, with

16 strong winds, due to possibility of destruction as they are high. by the winds. 9. If you have metal on your costume, such as 7. Seek shelter from lightning in a building; other­ golf spikes, get rid of it—you may be wise, in a cave, ditch, ravine, or under head- grounded and attract lightning strongly. high (at least) clumps of growth in open forest 10. Avoid hilltops, wire fences, metal clotheslines, glades. exposed sheds, and any electrically conductive 8. When there is no shelter, avoid the highest elevated objects. object in the area (and avoid being the highest 11. When you feel the electrical charge—if your object). If only isolated trees are nearby, your hair stands on end or your skin tingles—light­ best protection is to crouch or lie in the open, ning may be about to strike you. Drop to the keeping at least as far away from isolated trees ground immediately.

17 CHAPTER VII—MEDICAL AND HOSPITAL TORNADO AND SEVERE THUNDERSTORM PLANS

Presumably, medical and hospital readiness for person indoors who can announce an imminent disaster is well-organized and hospitals in each area strike of a tornado or severe thunderstorm over the have plans to back each other up in case of an over­ public-address system of the hospital. load of injured following a disaster, or in case one is Since electric power and communications will be badly damaged by a tornado or severe thunderstorm. all-important to the hospital in the hours following a Through arrangements in the Tornado Prepared­ disaster, it is assumed that standby emergency power ness Plan, each hospital should be alerted each time generation facilities would be in readiness. Emer­ a Tornado Watch or a Severe Thunderstorm Watch gency two-way radio communications may become is issued for the area; and should be immediately necessary, and may be supplied through the coopera­ notified whenever a Tornado Warning or a Severe tion of a law enforcement agency, an amateur radio Thunderstorm Warning is issued that might result group, or others. in a need for ambulances, doctors, and nurses. Usual provisions will have been made to call in As in the case of schools, hospitals should plan to doctors, interns, nurses, and nurses’ aids for emer­ do what can be done to protect patients, visitors, and gency service via a posted telephone list; and for hospital personnel if a tornado strikes the hospital. augmentation of the hospital switchboard staff. Employees should be drilled in emergency proce­ Through the efforts of the medical association or dures. Shelter areas (usually lower floors and inside of the Tornado Preparedness Committee, all doctors corridors, as well as bathrooms with their shielding and nurses should have in their possession at all walls) should be selected to protect from flying glass times special passes and windshield identification and other debris, and hospital personnel should be that allow them to pass immediately through law trained to know which areas are best. If there is time enforcement agency roadblocks on their way to assist before a tornado strikes, provision should be made to at disaster sites. block beds, at least in outer rooms, to keep them During Watch periods, it should be a definite from being rolled by strong winds. Some protection duty to ensure that ambulances are ready with all against flying debris may be afforded by shielding necessary equipment, and that suitable staff is ready bedfast patients with thick blankets and by moving to man them immediately. their beds to the inside walls of their rooms. If little To protect the hospitals themselves, trained sup­ time is available to take cover, patients may take plemental spotters should be posted outdoors to refuge in closets, or underneath their beds. maintain continuous watch for the approach of a It would be inadvisable to use elevators just before tornado or a severe thunderstorm. Preferably, they a tornado strikes because of probable power failure should be able to communicate immediately with a and possible wreckage of the cable penthouse.

18 CHAPTER VIII—POST-DISASTER RELIEF AND REHABILITATION

Many areas and communities already have a gen­ Representatives of the Civil Defense organization eral Disaster Plan which covers the range of require­ are well versed in these matters, as are local Red ments. Chapter 12 of “The Vice President’s Hand­ Cross Chapter officials. Additional information can book for Local Officials” (Nov. 1967) details the be secured from similar functionaries at the county, types of assistance available under the Federal Disas­ State, and national level. ter Relief Program, which is administered by the A suitable subcommittee should review and digest Office of Emergency Preparedness. It also includes a all such information for the Tornado Preparedness summary of the types of assistance available from Committee, and condense it for inclusion in the local other sources. Tornado Preparedness Plan. Complete and detailed information should be ob­ Especially important would be the description of tained by the Tornado Preparedness Committee con­ actions to be taken immediately after a disaster, as cerning the ready assistance that can be made availa­ indicated in Chapter III, together with the addresses ble to the local community or area in a post-disaster and telephone numbers of persons or agencies to be situation. contacted.

19 CHAPTER IX-SEVERE LOCAL STORMS WARNING SERVICE

An understanding of the functions, operation, and maximum amount of severe weather. Thus, each capabilities of the severe local storm warning service Watch area is surrounded by an area having an ex­ provided to the public by NOAA’s National Weather pected lower probability of occurrences with the Service will be helpful to any community or individ­ probability of such occurrences decreasing with dis­ ual interested in planning protection against these tance from the predicted area. The average lead time storms. This Commerce Department service has four (time interval between time of issuance by NSSFC main functions: and beginning of valid period) of Tornado and Se­ 1. The collection and analysis of existing weather vere Thunderstorm Watches is one hour. On occa­ conditions (such as surface and upper air ob­ sion it is possible to give a lead time of three to four servations, and thunderstorm reports) to deter­ hours. The valid time (time interval during which mine if severe weather (tornadoes or severe the National Weather Service thinks the average thunderstorms) is likely; weather will occur) of the Watch is usually six hours. 2. The issuance of Watches and Warnings; Public Severe Weather Watches released from the 3. The distribution of Watches, Severe Weather National Severe Storms Forecast Center are two Statements, Warnings and All-Clears to the types—Severe Thunderstorm and/or Tornado public so it will know what course of action to Watch. Examples are given at the end of this Chap­ take; and ter. 4. Public education on tornadoes and severe These public Severe Weather Watches are trans­ thunderstorms. mitted by internal National Weather Service and A specialized office, the National Severe Storms other meteorological communications circuits to local Forecast Center (NSSFC) is located at Kansas City, offices with county responsibility in the Watch areas Missouri. All bulletins announcing Tornado Watches specified in the bulletins. For Severe Weather Watch and Severe Thunderstorm Watches originate in the dissemination and warning purposes, each county in NSSFC. Experienced meteorologists constantly ana­ the United States is assigned to a nearby National lyze atmospheric conditions over the 48 contermi­ Weather Service office. These blocks of counties are nous States in order to detect those areas where referred to as county warning areas. The bulletins severe thunderstorms or tornadoes are likely to are also released by the NSSFC to the news wire occur. Also, when there is an occurrence, a special services. Entered on the press wires, they quickly analysis is immediately made to determine whether reach subscribers—newspapers, radio stations, and additional occurrences can be expected or whether television stations—serving the Watch area. the threat is a marginal one and can be expected to Normally, the bulletins are broadcast in a matter decrease. Due to various data restriction along with of a few minutes. They define watch areas in general the limitations in our current knowledge of the cause terms of sections of States. The period of time cov­ of such storms, it is not possible to predict the exact ered by the Watch—the “valid period”—is included, time of formation of tornadoes, or severe thunder­ as well as advice to be on the watch for local storms, or exactly where they will strike. Present weather developments and for later weather state­ severe local storm forecasting techniques are aimed ments and warnings. at predicting the areas (usually about 120 by 250 Responsible local offices of the National Weather miles in size) which are expected to contain the Service upon receipt of Watch bulletins via meteoro-

20 logical circuits, immediately prepare and issue a In the majority of instances, tornadoes do not redefining statement or “areal outline.” Redefining occur in areas covered by a Severe Thunderstorm statements are more detailed designations of the Watch, but in borderline cases it becomes difficult or parts of the States specified in the public Severe impossible to ascertain precisely whether the severe Weather Watch as likely to be affected by severe weather will be in the form of severe thunderstorms thunderstorms or tornadoes in terms of whole coun­ or tornadoes. For this reasons, and because severe ties, towns or well-known geographical landmarks. thunderstorms are in themselves capable of doing Local offices of the National Weather Service are considerable damage to heavily populated areas, all responsible for arranging for the dissemination of severe weather releases deserve careful attention. messages dealing with severe weather information A Tornado or Severe Thunderstorm Warning is throughout their assigned county warning areas. Var­ issued when a tornado or severe thunderstorm has ious communications arrangements are made. In actually been sighted in the area (usually by a severe States already served by NOAA Weather Wire, that weather spotter) or indicated by radar. Persons near, channel is used, and on some circuits the National and especially in the direction of travel of the severe Weather Service can energize a positive alerting de­ weather as stated in the Warning, should take imme­ vice to direct attention to the important bulletin on diate cover if they are quite close, or be prepared to the teletypewriter receiver. take immediate cover if they are farther away from the reported current location, but in the line of direc­ In addition to, or in the absence of, the NOAA tion of movement. In many cases, Warnings are made Weather Wire, other methods used for rapid dissemi­ possible through the cooperation of public-spirited nation include local teletypewriter circuits, telephone, persons who notify the nearest office of the National cooperating law enforcement and civil defense com­ Weather Service or community Warning Center munications networks, and special “hot-line” com­ when a tornado or severe thunderstorm is sighted. munications. By any or all of these means, the Na­ Warnings are issued immediately by the responsible tional Weather Service office alerts and keeps in­ office and indicate the location of the tornado or formed the cooperating newspapers, radio and televi­ severe thunderstorm at the time of detection, the sion stations, law enforcement agencies, civil defense area (usually counties) through which it is expected units, hospitals, spotters, school system headquarters, to move, and the time period (usually one hour) and others. Many of the recipients provide further during which it will move through the area warned. dissemination, by broadcast, transmission over The length of the area warned is equal to the dis­ agency communications networks, or by telephone. tance the tornado is expected to travel in one hour. The issuance of a Tornado Watch for a specific Examples of Watches, Warnings, and Severe Weather area should not be construed as indicating that no Statements are given at the end of this Chapter. tornadoes will occur outside of that area. It is em­ Severe Weather Statements are distributed by local phasized that the Watch designates the area in which offices of the National Weather Service to keep the tornadoes are most likely to occur. The Watch areas public fully informed of all current information, es­ are purposely kept as small as practicable in order to pecially when a Watch or Warning bulletin has been avoid needlessly alerting the residents of an unduly issued. Statements are issued at least once each hour, large area, but those in counties adjacent to Tornado and at more frequent intervals when severe weather Watch areas should maintain at least a casual watch develops or changes rapidly. on local weather developments. In this way, close watch is kept on weather devel­ The other type of public severe weather release by opments, and information on the current situation, NSSFC is a Severe Thunderstorm Watch. A thunder­ including rapid Warnings when necessary, is dissemi­ storm is considered to be “severe” if it contains ei­ nated to the counties for which the local office of the ther damaging winds (surface wind gusts greater National Weather Service is responsible. This alerts than 75 miles per hour) or hailstones at least % them to prepare for the worst, or informs them as inch in diameter at the surface of the ground, or soon as possible of the end of the threat. both. If one or more tornadoes are expected to be In order that the public in a Watch area may generated by the severe thunderstorms, a Tornado resume normal activities as soon as possible, local Watch is issued rather than a Severe Thunderstorm officers disseminate All-Clear bulletins as soon as Watch; and Tornado Watch bulletins always state advisable, informing a part or all of their county that severe thunderstorm activity is also expected. warning areas that the threat of severe weather no

21 longer applies. By this means successive areas, or one THIS WATCH INCLUDES THE COUNTIES OF . . . or more counties within one area, can be released (or the geographical area bounded by . . .) successively, while a Watch or Warning remains valid 3. TORNADO WARNING BULLETIN for the remainder, and for adjacent areas toward EANS (EMERGENCY ACTION NOTIFICATION which severe weather is still moving. SIGNAL) REQUESTED [NATIONAL WEATHER SERVICE] OKLAHOMA The term “bulletin” is used in the heading of se­ CITY OKLAHOMA vere weather Watches, Warnings and All-Clears. It ISSUED 4:00 PM CDT APRIL 30, 1967 indicates an urgent message affecting public safety, A TORNADO WARNING IS IN EFFECT UNTIL and receives preferential and more expeditious han­ 5:00 PM FOR PERSONS IN COTTON AND COMAN­ dling by news media and other users. CHE COUNTIES. A TORNADO WAS REPORTED BY THE PUBLIC 7 MILES EAST OF GRANDFIELD OKLAHOMA AT Examples 3:55 PM. THIS TORNADO IS MOVING TOWARD 1. TORNADO WATCH BULLETIN NUMBER 23 THE NORTHEAST AT 30 MPH. ISSUED 4 PM CST MARCH 2, 1967 TF A TORNADO IS SIGHTED OR THREATENING THE [NATIONAL WEATHER SERVICE] HAS IS­ CONDITIONS ARE SIGHTED ... BE PREPARED SUED A TORNADO WATCH FOR . . . TO MOVE TO A PLACE OF SAFETY. TO REPORT PORTIONS OF EASTERN LOUISIANA A TORNADO PLACE AN EMERGENCY COLLECT A PORTION OF WEST CENTRAL ALABAMA AND CALL TO THE OKLAHOMA CITY WEATHER MOST OF MISSISSIPPI [SERVICE OFFICE] OR CALL THE NEAREST LAW THE THREAT OF TORNADOES WILL EXIST IN ENFORCEMENT AGENCY. THESE AREAS FROM 5 PM UNTIL 11 PM CST THIS THURSDAY EVENING. SCATTERED SEVERE 4. SEVERE THUNDERSTORM WARNING BULLETIN THUNDERSTORMS WITH LARGE HAIL AND LO­ EANS REQUESTED CALLY DAMAGING WINDS ARE ALSO FORE­ [NATIONAL WEATHER SERVICE] WICHITA KAN­ CAST. SAS THE GREATEST THREAT OF TORNADOES AND ISSUED 4:40 PM CDT MAY 10, 1967 SEVERE THUNDERSTORMS IS IN AN AREA A SEVERE THUNDERSTORM WARNING IS IN ALONG AND 60 MILES EITHER SIDE OF A LINE EFFECT UNTIL 5:30 PM FOR PERSONS IN BUT­ FROM BATON ROUGE LOUISIANA TO TUPELO LER, COWLEY, ELK AND GREENWOOD COUN­ MISSISSIPPI. TIES. PERSONS IN OR CLOSE TO THE TORNADO A LINE OF THUNDERSTORMS WAS INDICATED WATCH AREA ARE ADVISED TO BE ON THE BY RADAR FROM WELLINGTON TO AUGUSTA WATCH FOR LOCAL WEATHER DEVELOPMENTS AT 4:35 PM. THE LINE OF THUNDERSTORMS IS AND FOR LATER WEATHER STATEMENTS AND MOVING TOWARD THE NORTHEAST. AT 4:35 WARNINGS. PM WELLINGTON, KANSAS REPORTED 70 MPH THIS WATCH INCLUDES THE COUNTIES OF . . . WINDS AND 1 INCH HAIL. (or the geographical area bounded by . . .) BE PREPARED TO MOVE TO A PLACE OF SAFETY IF HAIL OR THREATENING CONDITIONS ARE 2. SEVERE THUNDERSTORM WATCH BULLETIN SIGHTED TO REPORT LARGE HAIL OR DAMAG­ NUMBER 19 ING WINDS . . . PLACE AN EMERGENCY COL­ ISSUED 3:40 PM CST MARCH 4, 1967 LECT CALL TO THE WICHITA KANSAS WEATHER THE [NATIONAL WEATHER SERVICE] ISSUED A [SERVICE OFFICE] OR CALL THE NEAREST LAW SEVERE THUNDERSTORM WATCH FOR . . . ENFORCEMENT AGENCY. PORTIONS OF CENTRAL OKLAHOMA AND A PORTION OF SOUTH CENTRAL KANSAS 5. SEVERE WEATHER STATEMENT THE THREAT OF ONE OR TWO ISOLATED SE­ [NATIONAL WEATHER SERVICE] BIRMINGHAM VERE THUNDERSTORMS WITH LARGE HAIL ALABAMA AND DAMAGING WINDS WILL EXIST IN THESE ISSUED 4 PM CST JANUARY 20, 1967 AREAS FROM 6:00 PM UNTIL MIDNIGHT CST NO TORNADOES HAVE BEEN REPORTED IN THIS SATURDAY EVENING. NORTHERN ALABAMA UP TO 4 PM. IT IS STILL THE SEVERE THUNDERSTORMS ARE EXPECTED POSSIBLE FOR A FEW TORNADOES TO DEVELOP IN AN AREA ALONG AND 60 MILES EITHER SIDE IN PARTS OF NORTHERN ALABAMA UNTIL 6 OF A LINE FROM 40 MILES EAST OF WICHITA PM. KEEP TUNED TO YOUR RADIO OR TELEVI­ KANSAS TO 20 MILES SOUTH OF ARDMORE SION STATION FOR LATER INFORMATION. BE OKLAHOMA. PREPARED TO TAKE SAFE SHELTER IF A WARN­ PERSONS IN OR CLOSE TO THE SEVERE THUN­ ING IS ISSUED FOR YOUR LOCALITY OR IF THE DERSTORM WATCH AREA ARE ADVISED TO BE SKY BECOMES UNUSUALLY THREATENING. ON THE WATCH FOR LOCAL WEATHER DEVEL­ 6. SEVERE WEATHER STATEMENT OPMENTS AND FOR LATER STATEMENTS AND [NATIONAL WEATHER SERVICE] PEORIA ILLI­ WARNINGS. NOIS

22

x ISSUED 2 PM CST JUNE 14, 1966 ENID THROUGH CLINTON TO ALTUS HAVE THUNDERSTORMS ARE STARTING TO DEVELOP BEEN AND STILL ARE INCREASING RAPIDLY NEAR PEORIA ILLINOIS AT 2 PM. THIS IS THE IN INTENSITY. AT 3:45 PM THE HIGHWAY PA­ ONLY NEW DEVELOPMENT REPORTED SO FAR TROL AT CLINTON REPORTED WINDS OF 45 MPH IN CENTRAL ILLINOIS WHERE A FEW SEVERE AND V2 INCH HAIL. THIS LINE OF THUNDER­ THUNDERSTORMS WITH DAMAGING WINDS STORMS IS MOVING SOUTHEAST AT 30 MPH. ARE POSSIBLE UNTIL 6 PM. KEEP TUNED TO PERSONS IN THE AREA ALONG AND 30 MILES YOUR RADIO OR TELEVISION STATION FOR SOUTHEAST OF THIS LINE SHOULD BE ALERT LATER INFORMATION. TO THE POSSIBILITY OF DAMAGING WINDS AND HAIL UNTIL 5 PM. BE PREPARED TO TAKE 7. SEVERE WEATHER STATEMENT SAFE SHELTER IF A WARNING IS ISSUED FOR IMMEDIATE BROADCAST REQUESTED (when ap­ YOUR LOCALITY OR IF THE SKY BECOMES UN­ propriate) USUALLY THREATENING. [NATIONAL WEATHER SERVICE] OKLAHOMA (Note: When these messages were issued the National CITY OKLAHOMA Weather Service was the U.S. Weather Bureau, which became ISSUED 3:55 PM CST APRIL 13, 1966 the National Weather Service of the U.S. Commerce De­ DURING THE PAST 15 MINUTES THUNDER­ partment’s National Oceanic and Atmospheric Administra­ STORMS ALONG A LINE WHICH EXTENDS FROM tion in October 1970.)

23 CHAPTER X—DESCRIPTION AND CLIMATOLOGY OF TORNADOES AND SEVERE THUNDERSTORMS

The importance of the geographic, seasonal and period, the 1953-1969 period is more representative diurnal distribution of tornado occurrences must be since it coincides with increased public awareness of considered in community tornado preparedness plan­ tornadoes and the development of the tornado fore­ ning. Any plan developed should take into account casting service. For the same period, the annual the risk in a particular area. Tornadoes occur in average number of tornado days (days with one or many parts of the world and in all 50 States, but no more tornadoes) was 159. Average annual frequency area is more favorable to their formation than the by State for this period (without regard to size of continental plains of the United States (see Figure State) ranges from 103 tornadoes in Texas to less 1) and no season is free of them. Normally, the than three in most of the northeastern and far west­ number of tornadoes is at its lowest in the United ern States and less than one in Oregon and Nevada. States during December and January, and at its peak In 1967, 912 tornadoes were reported, constituting in May (see Figure 4). The months of greatest total an all-time high. Texas, Oklahoma and Kansas expe­ frequency are April, May, and June. rienced the greatest number of these storms. In February, when tornado danger begins to in­ crease, the center of maximum frequency lies over Characteristics of Tornadoes the central Gulf States. Then, during March, this A Tornado is a violently rotating column of air center moves eastward to the southeast Atlantic pendant from a thunderstorm cloud and touching the States, where tornado frequency reaches a peak in ground. It nearly always starts as funnel-shaped ro­ April. During May, the center of maximum frequency tating extrusion from the thunderstorm cloud, builds moves to the southern plains States and, in downward to the ground, and darkens as it picks up June, northward to the northern plains and the Great debris. On a local scale it is the most destructive of Lakes areas as far east as western New York State. all atmospheric phenomena. The reason for this drift is the increasing penetration of warm, moist air from the south while contrasting Tornadoes form several thousand feet above the cool, dry air still surges in from the north and north­ earth’s surface, usually during warm, humid, unset­ west. Tornadoes are generated with the greatest fre­ tled weather, and usually in conjunction with a se­ quency along the boundary between these air masses. vere thunderstorm. Sometimes a severe squall line Thus, when the Gulf States are blanketed by warm many miles long may contain a number of tornado- air and there is no cold air intrusion to speak of, the producing thunderstorms. tornado frequency drops. This is the general situa­ Sometimes a series of two or more tornadoes is tion across the Nation after June. However, torna­ associated with a parent thunderstorm (and there does may also be generated in connection with hurri­ have been a number of times when two tornadoes canes. Winter cooling permits fewer and fewer en­ have occurred simultaneously, pendant from the counters between warm and cold air, and tornado same thunderstorm). As the parent thunderstorm frequency reaches its lowest level in December. moves along, tornadoes may form, travel along in During the period 1953-1969, an average of 642 touch with the ground for a few miles, dissipate or tornadoes a year occurred in the United States, about lift, and then touch down again—sometimes several half of them during three months—April, May and times. June. Although records have been kept for a longer Because one or more tornadoes may develop in a

24 given situation jrom one or more thunderstorm lapse or topple outward, windows explode, and de­ clouds, and their period of contact with the ground bris of this destruction is driven through the air in a may be short, prolonged, or intermittent, Watches dangerous barrage. Heavy objects like machinery and Warnings of tornadoes and severe thunderstorms and railroad cars have been lifted and carried for must be issued on an area basis, rather than for a considerable distances. particular location. Knowledge of the following general characteristics Wind Speeds of tornadoes is useful in tornado preparedness plan­ ning and to individuals: Vertical and horizontal wind speeds within the vortex of a tornado have never been measured di­ TIME OF DAY during which tornadoes are rectly by instruments exposed in the tornado funnel. most likely to occur is mid-afternoon, generally Invariably, the instruments are destroyed by the between 3 and 7 p.m., but they have occurred storm. Engineering studies of tornado damage show at all times of day. that the horizontal wind speed in the center of a DIRECTION OF MOVEMENT is usually from tornado may be more than 300 miles per hour. The southwest to northeast. (Note: Tornadoes asso­ wind speed diminishes rapidly away from the funnel ciated with hurricanes may move from an east­ and is relatively light just a few feet from the area of erly direction.) destruction. LENGTH OF PATH averages 4 miles, but may reach 300 miles. A tornado traveled 293 The Casualty and Damage Potential. . miles across Illinois and Indiana on May 26, 1917, and lasted 7 hours and 20 minutes. The greatest potential for casualties from torna­ WIDTH OF PATH averages about 300 to 400 does is not necessarily where the greatest number of yards but tornadoes have cut swaths a mile and tornadoes occurs, but where there is a combination more in width. of high tornado incidence and a dense concentration SPEED OF TRAVEL averages from 25 to 40 of population. For example, the greatest number of miles per hour, but speeds ranging from station­ tornadoes, per 10,000 square miles, occurs in Okla­ ary to 68 miles per hour have been reported. homa (Figure 1) and Texas has had more tornado THE CLOUD directly associated with a tor­ caused deaths than any other State (Figure 2). Be­ nado is a dark, heavy cumulonimbus (the fa­ cause of population density, the tornado threat is miliar thunderstorm cloud) from which a whirl­ greatest in Massachusetts (Figure 3). All communi­ ing funnel-shaped pendant extends to the ties in the Midwest, Great Plains and the southeast­ ground. ern States, regardless of size, and many populous PRECIPITATION associated with the tornado areas in the northeastern States, should have active usually occurs first as rain just preceding the community protection plans for coping with tornado storm, frequently with hail, and as a heavy situations. downpour immediately to the left of the torna­ The mathematical chance that a specific location do’s path. will be struck by a tornado in any one year is quite SOUND occurring during a tornado has been small. This low risk factor undoubtedly contributes described as a roaring, rushing noise, closely to apathy toward tornado preparedness planning approximating that made by a train speeding until a community has suddenly been the scene of a through a tunnel or over a trestle, or the roar of major tornado disaster. However, the low risk for a many airplanes. particular location mujst be weighed against the cas­ ualty potential of a tornado disaster in an unpre­ pared community. When these two factors are con­ The Work of Winds and Pressure sidered, it becomes apparent that few communities The destructive power of a tornado is due to the can afford to forego tornado preparedness planning. combined action of its strong rotary winds and the Tornadoes have occurred with exceptional fre­ partial vacuum in the center of its vortex. As a quency at particular locations: tornado passes over a building, the winds twist and —Oklahoma City has been struck 26 times rip at the outside at the same time that the abrupt since 1892; pressure reduction in the tornado’s “eye” causes ex­ —Baldwyn, Mississippi, was struck twice in 25 plosive over-pressures inside the building. Walls col­ minutes on March 16, 1942;

25

i —Two tornadoes 45 minutes apart on May 30, Another major series of tornadoes killed 268 peo­ 1879, left a large part of Irving, Kansas, in ple and injured 1,874 in Alabama on March 21, ruins; 1932. Property damage amounted to approximately —Austin, Texas, was struck twice in rapid suc­ 5 million dollars. cession on May 4, 1922; and The outbreak of 37 tornadoes on Palm Sunday, —Codell, Kansas, was struck on May 20, 1916, April 11, 1965, killed 257 people and injured over again on May 20, 1917, and a third time on 5,000 persons in the Midwest. Associated property May 20, 1918! losses were in the millions of dollars. Not many people in any of the above places would feel justified in assuming that it would necessarily be Characteristics of Severe Thunderstorms a long time until the next tornado occurred. Simi­ Severe thunderstorm clouds are the breeding- larly, no one in a location that has not yet experi­ places for tornadoes, and have the same characteris­ enced a tornado should assume that there will never tics as the clouds directly associated with tornadoes be one there. In the area of the battle between the except that they do not have rotating pendants ex­ warring air masses, it is wise to be prepared for the tending to the ground, and the sounds characteristic worst. of tornadoes are lacking. However, severe thunder­ storm clouds sometimes produce funnel clouds Major Tornadoes (which are incipient tornadoes) that rotate and are The most death-dealing series of tornadoes on rec­ pendant from the parent cloud, but do not reach the ord occurred during the late afternoon on March 18, ground. 1925, in portions of Missouri, Indiana, Illinois, Ken­ Severe thunderstorms occur much more frequently tucky, and Tennessee. Eight separate and distinct than tornadoes, and in the same areas; and their tornadoes were observed. One of these killed 689 destructive effects on trees, power lines, houses, mo­ persons, injured 1,890 and caused more than 16 bile homes, and crops are well-known. Deaths and million dollars in property damage. The other seven injuries resulting from lightning, strong nonrotating tornadoes of the series increased the total loss of life winds, and large hail can be reduced by adequate to 740 and contributed significantly to the total cas­ warning and rapid, well-organized rescue operations ualty and property damage. and medical assistance.

Figure l

26 F

Figure 3 THREAT RATING FROM TORNADOES, 1953-1969 Figure 4 TORNADO INCIDENCE BY MONTH 1953-1971