DOCOMINTREM/1W ED 148 61.5 SE 023 734(2 TITLE /Spotter's Guide fot Identifying ana Repotting Sevezre Local Storms. TNSTITUTION. National Oceanic apd AtmospheicsAdiinistration (DOC), Rockville, Md. REMIT. NO. NOAA-PA-70011 PUB DATE 74* NOTE 17p.; Photographs may notteproduce well AVAILABLE FROM,Superintendent of Documents, U.S. GoVernment Printitg Office, Washington, D.C. 20402 (Stockk Number . 003-018-00006-7, $0.40) EDRIPRICE 'MF-$0.83 HC-$1.67 Plus Postage. DESCRIPTORS G *Climatic Factors; Earth Science. Ellyironmental Education; *Environmental Influnces`; *Guides; .*Instructional Materials; *Meteorology; Natural Sciences; Physical EnvironmOnt; Science*Edgcation IDENTIFIERS *Tornadoes ABSTRACT This guide is designed to assist personnel _working in the, National Weather Service's 'Severe Local Storm Spotter Networks in- identifying and reporting ,severe local storms. Provided are,pidtures of cloud types for severe storms including tornadoes., hail, thunder, lightning, heavy rains, and waterspouts. Instructions for key indications to watch for and detailed reporting pr'oc'edures are also included. (SL)' a 4 ******************************'***************************************** * Documents acquired by ERIC include many informal unpublished * materials not available from other sources.- ERIC makes every effort * * to obtain the best copsnavailable. Nevertheless, items of marginal * * reproducibility are often encountered and thisa'ftects,the quality * * of the microfiche and hardcopy reproductions ERIC makes available * ',I, via the ERIC Document Reproduction Service (EDRSY. EISis not * sOonsible for the quality of the original document. Reproductions * * supplied by EDA,Vate the best that can be made from the original. * ********************************************A************************** I 4.= .U.S. DEPARTMENT OF COMMERCE , Nationaipccanic and Atmospheric Administration ,ounT'co,, 1 +, 4.):ITEs 04 -SPOTTER'S GUIbE for Identifying and' Reporting 1 1 US DEPARTMENT OF HEALTH EDUCATION a WELFARE rtz., NATIONAL INSTITUTE OF 'EDUCATION 111 hiis DOCUMENT HAS BEEN REPRO- DUCED EXACTLY AS RECEIVED FROM fl THE PERSON OR ORGANIZATIONORIGIN ATING IT POINTS OF VIEW OR OPINIONS STATED DO NOT NECESSARILY REPRE SENT OFFICIAL NATIONAL INSTITUTE OF EDUCATION POSITION OR POLICY z &Li St t . A ,residentialstreetissmashedto matchwood by the Topeka, Kansas, tornado of June 8, 1966. Photo by H. E. HoMmerlt,Chrtktopher,Studio. CoverA killer tornado stalks Tracy, Minnesota, June 13, 1968. This storm traveled.. 13 miles along the ground, and killed nine people, injured about 100 more, and caused several ntillion dollars' property damage: A member of Lyon County's effective Severe Local Storm Spotter Network sighted the tornado and alerted Tracy's community warning center, which sounded the Civil Defbnse sirens for seven minutes before the twister struck the town. Those seven minutes kept the death toll down in Tracy. As aSevere Local Storm Spotter for the National Weather Service you may give your community this gift of timethe seconds that save lives. PhotobyEric Lantz, Walnut66.ve (Minn )Tribune rC' 2 ti To the Sevjre Local) Storm Spotter: The National Weather Service of NOAA, the U.S. Commerce Department's National Oceanic and Atmospheric Administration, and cooperating organi ations have established Severe Local Storm Spotter Networks in order to secure critical information on severe local storms. This Guide is des cued to assist you, the spotter, in identifying and reporting these severe local storms. The severe local storm forecaster analyzes the weather and identifies the general areas'reas favorable for severe local storm development. He then issues a severe thunderstorm, or tornado watch. However, &specific warning can be made bnly after a severe storm is in progress and a report has been received on its type, location, and direction of movement. This is where you come in. Radar is very important, where avail- able, but it is not the whole answer. We need your 'reports, Then we can warn others.. You are a vital member of the team. Thank youfpr helping usand, more -importantly, your fellow citizens. Your oily compensation will be the, knowledge that your vigilance May save lives and property. // 4 Sincerely yours,// elit/40416-114 G,eorg ssman Director, N tional Weather Service . SEVERE LOCAL STORMS .'" begin as thunderstorms, the great Cumulo- These disturbances are perhaps most nimbus towers built by unstable conditions severe when vthey occur along squall lines, in the lower atmosphere. Like most storms, which are gen4ated when cold dense air thunderstorms run on heat energy converted and warm moist air fight along boundaries into wind, electrical discharge, anviolent called fronts. The greater the contrast in upward motion of theair.Severe local' temperature and moisture across the front, storms may develop' from local heating of the greater the energy cofitent-, and the more the ground or radiational cooling of cloud violent theensuing thunderstorms. topsanything which puts dense, colder air Becausethunderstorms may\ extend from near the earth's surface into the strato- abOve warm, moist, less-dense air. sphere, they may literally blot out the sun. The Cumulus family of clouds represents Remember, the darker the sky, the ireater such instability. Sometimes one or several the vertical extent of the cloud, and the more fair-weather Cumuli will develop vertically likely the storm will be severe. Remember/ until they become thunderheads; further de- also that, given the proper season and gel velopment causes the thundershower to in- graphic location, severe thunderstorms may tensify into a severe local storm. develop from shallower cloud systems. .3 2 Viewed from below, the ragged bases Mammatus cloud forms are series of of a squall line or large thunderstorm are pouches projecting downward from the base windtorn, twisting, and rolling. This random of storm clouds. These pouches are usually motion should not be-Confuse.ith the uniform ill size and shape, appear and flatten definite, sustained pattern of rot. about gradually, and have no spinning motion. a central point that produces a funnel. Although these thunderstorm forma- tions are not tornadoes, they are often observed Under tornado-producing se- vere storm conditions. A storm with developingrotarycirculationsand mammatus clouds is a storm to watch SEVERE LIGHTNING, HEAVY RAINS, DESTRUCTIVE WINDS, AND LARGE, HEAVY HAIL ARE OFTEN "ADVANCE MEN" FOR THE MOST VIOLENT STORM ON EARTHTHE TORNADO. SK AR 6 5 You can tell something about a thun-. derstorm'S severity by, observing the intensity of its rain and the strength of its' winds, and by 'watching for the occurrence of certain unique, destruc- tive phenomena. LIGHTNING is the discharge pro- duced when differences in ground and at- mospheric electrical.charge are large enough to overcome the insulating effect N air.-The discharge may occur within the cloud, be- tween clouds, or between the cloud and ground.Usually, the more lightning qb- served in a thunderstorm, the more intense the storm system. Be careful. Remember that lightning kills more Americans annual)/ than hurricanes or tornadoes. xF THUNDER is the sound produced by expansion of air heated by the high- amper- age lightning stroke. The distance in miles to the lightning flash cap.-be estimated by .1 counting the number of seconds between I- lightning and thunder, and dividing by five. HAIL isprecipitation in the 'form of lumps of ice, called hailstones. The size of hailstones is an indicator 'of thunderstorm intensity. HEAVY RAINS mark the Mature stage of a thunderstorm, and may produce dangerous flash floods even before precipi- tation' ceases. Stay out of dry creek beds during thunderstorms. If you live along a river, listen for flashflood warnings from the National Weather Service: REPORT THE DISTANCE AND DIRECTION TO INTENSE, FREQUENT LIGHTNING AND THUNDER AND DESCRIBE THE TYPE OF DISCHARGE: GROUND-TO-CLOUD, CLOUD-TO-CLOUD, CLOUD-TO-GROUND. AR S ota 1:177arai;EN-st a YJ 4 t I r"" ' :0.4 1%1 .e 4-- .71--2.3.ta 4075t. - -f,'$"taia3;44.A....,1t. , r J. r.1 `- , - -at4. _ig'-' "r-soitkagigi, .1":71%--410WSaziges-:;ai-.-__ .0; . -sc":. - REPORT HAILSTONES MORE THAN 1/4-INCH IN DIAMETER. REPORT HEAVY RAIN AND ALL FLOODING t. TORNADOES 3, 1. are violently rotating 'columns of air that warm fir from the south, and cold air from descend in the familiar funnel shape from the north; and in the middle and late after- thunderstorm cloud systems. A tornado vor- noon, when a warm day is at its warmest. texis normally several hundred yards in Because theyareoften accompanied by diameter, whirls usually in a counterclock- heavy rain, hail, lightning, and the obscuring wise direction (in the Northern Hemisphere), cloud system of the thunderstotkor squall and contains winds estimated to be near 300 line, these violent storms are sometiates diffi- miles per hour. Tornadoes occur on all con- cult to identify. This difficulty is of course tinents, at any time of year, at any hour of much greater when tornadoes occkr at night. the day. They have occurred in every state of the Union. you can be an effective spotter if Theirgreatestfrequencyisinthe spring, when large contrasts exist between yoiiknow what to kook and listen for. 9 4 LOOK FOR ANY PROTUBERANCE OR ROTARY MOTION AT* THE BASE OF A THUN -. DERCLOUD SYSTEM The ragged trailing clouds of squall - lines, and certain other harmless phenomena (see pages 14, 15) are sfrequently mistaken fortornadoes.'Organizedrotarymotion about a vertical Vis is the clue to distin: guishing harmless, clouds and the funnel of a developing tornado. In the random motion of thunderstorm. clouds, funnel clouds ap- pear as highly organized, rapidly rotating systems. Funnel clouds are violently rotating columns of air, usually pendatif from a Cu- mulonimbus cloud, that do not touch the ground. They become tornadoeS only when they reach the surface. ANY ROTATING CLOUD OF DEBRIS OR DUST NEAR THE GROUND. Some tornadoes drop from a thunder- storm cloud without developing avisible .funnel-shaped cloud of theiprown. These in- visible whirlwinds first become visible when the violently spinning column of air begins picking up debris or dust from the ground.