VOL. 5, No.2 WEATHER AND FORECASTING JUNE 1990 The National Hurricane Center-Past, Present,and Future ROBERTC. SHEETS National Hurricane Center. Coral Gables. Florida (Manuscript received5 January 1990,in final fonn 15 February 1990) ABSTRACf The National Hunicane Center (NHC) is one of three national centersoperated by the National Weather Service(NWS). It has national and international responsibilitiesfor the North Atlantic and eastern North Pacifictropical and subtropicalbelts (including the Gulf of Mexico and the CaribbeanSea) for tropical analyses, marine and aviation forecasts,and the tropical cyclone forecastand warning programsfor the region. Its roots date back to the I 870s,and it is now in the forefront of the NWS modernizationprogram. Numerouschanges and improvements have taken place in observationaland forecastguidance tools and in the warning and responseprocess over the years. In spite of all theseimprovements, the loss of property and the potential for lossof life due to tropical cyclonescontinues to increaserapidly. Forecastsare improving, but not nearly as fast as populationsare increasingin hunicane prone areassuch as the United StatesEast and Gulf Coast banier islands.The result is that longer and longer lead times are required for communities to preparefor hunicanes. The sealand over lake surgefrom hurricanes(SLOSH) model is usedto illustrate areasofinnudation for the Galveston/Houston,Texas; New Orleans,Louisiana; southwestRorida; and the Atlantic City, New Jersey areasunder selectedhunicane scenarios.These results indicate the requirementfor lengthy evacuationtimes. The forecastand warning processis then illustrated, starting with tropical analyses,numerical guidance,the meteorological/hydrologicalcoordination of the forecast,and finally the warning coordination and response process.Examples are usedto illustratethe sensitivityof the warningand responseprocess to preplanning based upon SLOSH model results,the coordination betweenNWS and local and stateofficials, and the critical role played by the media for motivating peopleto take the desiredaction in an orderly fashion. Theseexamples iUustratehow this processworked to nearperfection during HurricaneHugo, but wasdisrupted in the Galveston/ Houston area by conflicting information reachinglocal officials and the public during HurricaneGilbert. Finally, a brief look into the futureis attempted,with emphasisupon new observingsystems, next generation numerical modelsand expectedimprovements in tropical cyclonetrack and intensity forecastsand the warning processat landfall and inland. The next generationweather radar (NEXRAD) systemsin the modernizedand restructuredNWS are expectedto playa major role in improving short-term warningsof flash floods, high winds, and possibletornadoes as hurricanesmove inland and start to decay. Contents 3. Meteorologicalsatellites 4. Radar Abstract 5. Buoys,ships, and conventional systems 1. Introduction a. General 3. Current structureand responsibilities b. The United Stateshurricane problem a. Structure b. Responsibilities 2. History I. Tropical analysis, forecasts, and associated a. General b. Observational,data processing,and communication products 2. The tropicalcyclone forecast and warningprocess systems (i) Beforethe stonn 1. Data processingand communications (ii) The forecast:tools and techniques 2. Aircraft reconnaissance (iii) The forecast:the process (i) Air Force (iv) The forecast: meteorological/hydrological (ii) Navy coordination (iii) Commerce (v) The warning 4. Operationalexamples Correspondingauthor address:Dr. Robert C. Sheets.Director, a. Forecasts National Hurricane Center, NOAA{ERL, IRE Building. Rm 631, I. Hurricane Jerry, October 1989 1320S. Dixie Highway, Coral Gables,FL 33146. 2. Hurrican Hugo, September1989 185 @ 1990 American Meteorological Society 186 WEATHER AND FORECASTING VOLUME5 b. Nationaland internationalcoordination (NSSFC) located in Kansas City, Missouri and the 1. HurricaneHugo, September 1989 parentNational Meteorological Center (NMC) located c. Conflictinginformation near Washington, D.C. The responsibilities of NHC 1. HurricaneBabe, September 1977 are much broader than providing forecastsand warn- 2. HurricaneGilbert, September 1988 ings for tropical cyclones(hurricanes). Responsibilities also include tropical analyses,interpretive messages, 5. Futurehurricane forecast and warning operations public, and marine and aviation forecastsyearlong for national and international interests. The area of re- 6. Concludingremarks sponsibility includes the tropical and subtropical re- Acknowledgments gions of the North Atlantic and eastern North Pacific oceans,the Caribbean Sea, the Gulf of Mexico and References adjacentland areas. Although the NHC has numerous other responsi- 1. Introduction bilities, it is best known for its hurricane forecastand warning programs. These programs have been highly a. General visible becauseof large lossesof property and lives due The National Hurricane Center (NHC) located in to hurricanes in the past. A continuing concern is that Miami, Florida is one of three national centersoperated potential lossdue to hurricanes is increasing daily due by the National Weather Service (NWS). The other to population growth in vulnerable areasin the United two are the National Severe Storm Forecast Center Statesand elsewherein this hemisphere.To understand JUNE1990 ROBERT C. SHEETS 187 the presentand future structure and operations of the the immediate coastto move inland when hurricanes NHC, one needsthe perspectiveof its history and the havethreatened. However, it is becomingmore difficult changing nature of the hurricane threat to the citizens eachyear to evacuatepeople from these areasdue to of the westernhemisphere and specificallyto Gulf and roadwaysystems that have not kept pacewith the rapid East Coast residents of the United States. population growth. This condition results in the re- quirement for longer and longer lead times for safe b. The UnitedStates Hurricane problem evacuation. Unfortunately, these extended forecasts suffer from increasinguncertainty. Furthermore, rates The permanent populations of the hurricane-prone of improvements in forecastskills have been far out- coastalcounties of the United Statescontinue to grow pacedby ratesof population growth in areasvulnerable at a rapid rate (Fig. I ).'When weekend,seasonal, and to hurricanes. holiday populations are considered, the number of The combination of the growing populations on people on barrier islands suchas at OceanCity, Mary- barrier islandsand other vulnerable locations (seeFig. land, Gulf Shores,Alabama, and Padre Island, Texas 2), and the uncertainties in the forecastsposes major increase by 10- to 100-fold or more. Also, theseareas dilemmas for forecastersand local and stateemergency are subjectto inundation from the rapidly rising waters managementofficials alike, i.e., how do you prevent known as the storm surge associatedwith hurricanes complacencycaused by ..falsealarms" and yet provide that generally result in catastrophic damage and po- adequatewarning times? tentially large lossesof life. Over the past severalyears, Preparations for hurricanes are expensive.When a the warning systemhas provided adequatetime for the hurricane is forecastto move inland on a path nearly great majority of the people on barrier islandsand along normal to the coast the area placed under warning is about 300 miles in length. The averagecost of prepa- ration, whether the hurricane strikes or not, is more than $50 million for the Gulf Coast.This estimatecov- ers the cost of boarding up homes, closing down busi- nessesand manufacturing plants, evacuating oil rigs, etc. It does not include economic lossesdue to disrup- tion of commerce activities such as sales,tourists can- celing reservations,etc. In some locations, the loss for the Labor Day weekendalone can be a substantialpor- tion of the yearly income of coastal businesses.An ex- ample of suchlosses were experiencedalong the Florida panhandleduring Hurricane Elena in 1985.If the width of the warned area has to be increasedby 20%because of greateruncertainties in the forecast, the additional cost for eachevent would be $10 million. Ifuncertain- ties in the hurricane strength require warning for the next higher category of hurricane (Saffir / Simpson scale, Hebert and Taylor 1988), then major increases in the number of people evacuated and preparation costswould be required. Of course, if theseuncertain- ties meant that major metropolitan areassuch as Gal- veston/Houston, New Orleans, Tampa, Miami, or a number of other major coastal cities would or would not be included in the warning area, the differencesin preparationcosts would be substantiallymore than the $10 million, and the number of people evacuated would be substantiallymore than the tens of thousands of people. For instance, in the case of the Galveston/ Houston area, an increase in storm strength of only 20 miles h -I (from a category-2hurricane to a category- 3 hurricane on the Saffir/ Simpson scale)would require the evacuation of an additional 200 000 people. Like- wise, if major industrial areassuch as Beaumont/Port Arthur, Texas, or tourist areas such as Atlantic City, New Jerseywere affected by these uncertainties, the financial impact would be quite large. Economic factorsreceive serious consideration from VOLUME5 fiG. 2. Predicted inundation causedby the storm surgegenerated by a hurricane moving ashore on the track indicated by the bold straight line for the (a) Galveston/Houston, Texas area