Forecast of Atlantic Seasonal Hurricane Activity for 1994

摘要

This paper presents details of the author's forecast for the amount of tropicalcyclone activity expected to occur in the Atlantic Ocean region including the Caribbean Sea and the Gulf of Mexico during 1994. This forecast is based on the author and colleague's ongoing research relating the amount of seasonal Atlantic tropical cyclone activity to five basic physical parameters. These are: (1) the Quasi-Biennial Oscillation (QBO) of equatorial stratospheric wind; (2) the El Nino Southern Oscillation (ENSO); (3) West African Rainfall (AR) anomalies during the previous year; (4) anomalous west to east gradients of surface pressure and surface temperature (delta PT) in West Africa during February through May; and (5) Caribbean Basin Sea Level Pressure and Upper level Zonal Winds Anomalies (SLPA and ZWA respectively). Information received by the author up to 6 June 1994 indicates that the overall 1994 hurricane season should be a below average with about 5 hurricanes (average is 5.7), 9 named storms (average is 9.3) of at least tropical storm intensity, a total of about 15 hurricane days (average is 23), 35 named storm days (average is 46) and total Hurricane Destruction Potential (HDP) of 40 (average is 68). It is also expected that there should be only one intense or major hurricane of Saffir/Simpson intensity category 3, 4, or 5 this season (average is 2.2) and only about 1 major hurricane day (average is 4.5). These parameters represent an overall measure of total hurricane and tropical cyclone activity which is only about 70% of the last 44-year average. The amount of hurricane activity in this forecast has been reduced from that in the author's 19 November 1993 forecast and update discussion of 11 March 1994 at the New Orleans National Hurricane Conference. This forecast reduction is due to the slower than anticipated dissipation of the current El Nino, new estimates of West African February through May surface east-west pressure and temperature gradients, and to above average values of April-May Caribbean basin SLPA and ZWA values. This forecast will be updated on 5 August 1994, just before the beginning of the climatologically most active part of the hurricane season. The updated August forecast will make use of June and July data and should provide a more reliable forecast, particularly with regard to the African rainfall as it related to prospects for intense hurricane activity. The updated forecast will also provide a much better gage on the extent of expected dissipation of the current El Nino event.