HURRICANE FORECASTING

(Meteorology and Statistics) Hurricane tracking and estimation in the United States is centered in the federal government's National Hurricane Center in Coral Gables, Florida. However, one pioneering effort in the application of statistical analysis and econometric techniques to hurricane analysis and forecasting has been undertaken by William Gray, professor of meteorology at Colorado State University in Fort Collins, Colorado. Dr. Gray's research is based on the foundation that hurricanes are caused by global, rather than local factors, to include the influence of El Niño (El Niño Effect, resulting in reduced hurricane activity as opposed to the La Niña when hurricanes tend to be more common) in the eastern equatorial Pacific Ocean as well as wind directions (pressure differentials) and precipitation levels. His research has led to an extensive quantitative expression to estimate both the number and intensity of hurricanes in the western Atlantic region (to include the Caribbean and Gulf of Mexico) during the usual peak hurricane season of mid-August through mid-October. The following relationship represents an Econometric Model for forecasting hurricane activity based upon a number of climatological explanatory factors covering a vast geographic range. Hurricane Activity = ß0 + ß1(1U50 + a2U30 + a3U50 - U30) + ß2(4Rs + a5Rg + a6ÞxP + a7ÞxT) + ß3(a8SLPA + a9ZWA + a10SSTA + a11ÞtSSTA + a12SOI + a13ÞtSOI) Hurricane Activity = ß0 + ß1(1U50 + a2U30 + a3U50 - U30) + ß2(4Rs + a5Rg + a6ÞxP + a7ÞxT) + ß3(a8SLPA + a9ZWA + a10SSTA + a11ÞtSSTA + a12SOI + a13ÞtSOI) Hurricane Activity = ß0 + ß1(1U50 + a2U30 + a3U50 - U30) + ß2(4Rs + a5Rg + a6ÞxP + a7ÞxT) + ß3(a8SLPA + a9ZWA + a10SSTA + a11ÞtSSTA + a12SOI + a13ÞtSOI); where: The ß's and a's are empirically derived coefficients (parameters) for prior years of data; U50 and U30 are extrapolated September quasi-biennial oscillation (QBO: the tendency for equatorial winds 13 to 16 miles above the earth to change direction from east to west and vice versa) zonal winds at 30 and 50 mb at 10N latitude; U50 - U30 is the absolute value of the extrapolated vertical wind shear between 50 and 30 mb; U50 - U30 is the absolute value of the extrapolated vertical wind shear between 50 and 30 mb; Rs is the western Sahel (western portion of Africa's Sahara desert) precipitation in the previous August and September; Rs is the western Sahel (western portion of Africa's Sahara desert) precipitation in the previous August and September; Rg is the previous year August to November precipitation in the Gulf and Guinea region; Rg is the previous year August to November precipitation in the Gulf and Guinea region; ÞP is West African anomalous east-west pressure gradient deviation in February through May; ÞP is West African anomalous east-west pressure gradient deviation in February through May; ÞT is West African anomalous west-east temperature deviation in February through May; ÞT is West African anomalous west-east temperature deviation in February through May; SLPA is the April-May Sea Level Pressure Anomaly in the lower Caribbean basin; SLPA is the April-May Sea Level Pressure Anomaly in the lower Caribbean basin; ZWA is the April-May Zonal Wind Anomaly in the Caribbean basin; ZWA is the April-May Zonal Wind Anomaly in the Caribbean basin; SOI is the April-May normalized Tahiti minus Darwin Sea Level Pressure differences; SOI is the April-May normalized Tahiti minus Darwin Sea Level Pressure differences; SSTA is the April-May Sea Surface Temperature Anomaly in Nino 3 (El Niño); SSTA is the April-May Sea Surface Temperature Anomaly in Nino 3 (El Niño); ÞSOI is the recent months change in SOI from January-February to April-May; ÞSOI is the recent months change in SOI from January-February to April-May; ÞSSTA is the recent months change in SSTA from January-February to April-May. ÞSSTA is the recent months change in SSTA from January-February to April-May.