* ATLANTIC TC GENESIS INDEX * * GFS VERSION * * AL172020 09/21/20 00 UTC * TIME (hr) 0 6 12 18 24 36 48 60 72 84 96 108 120 Prob of Genesis 23% 47% LAT (deg N) 34.4 33.9 33.9 34.3 34.7 35.9 36.4 36.0 34.9 33.6 32.1 30.0 28.2 LON (deg W) 31.2 30.8 29.5 27.9 25.9 22.1 19.3 17.4 16.0 16.4 17.2 19.1 21.7 DTL (km) 1859 1802 1693 1585 1439 1186 929 768 668 643 617 632 751 TRACK SOURCE AP04 AP04 AP04 AP04 AP04 AP04 AP04 AP04 AP04 AP04 AP04 AP04 AP04 TCGI 0-48h Genesis Forecast: 23% is 0.8 times the sample mean ( 30%) TCGI 0-120h Genesis Forecast: 47% is 1.1 times the sample mean ( 43%) --------------------------------------------------------------------------------------------- INDIVIDUAL PREDICTOR CONTRIBUTIONS TO PROBABILITY OF GENESIS ******* 48-HR ****** ******* 120-HR ****** AVG TCGI CONT AVG TCGI CONT DIVERGENCE -1.0 0.8 2.8% 1.0 1.2 5.1% VORTICITY 1.7 3.5 9.5% 1.4 3.0 22.4% VERTICAL SHEAR 16.3 16.9 10.0% 18.4 14.7 17.4% RH 73.1 55.2 0.0% 70.9 55.4 1.0% GOES 29.1 0.0 0.0% 29.3 0.0 0.0% DVORAK 0.8 0.5 1.2% 0.8 0.5 1.6% --------------------------------------------------------------------------------------------- PREDICTOR DEFINITIONS (Averaged Over 500 km Radius) GENESIS CLIM = Climatological Prob (%) of Genesis (Source: NHC-TAFB Invest Database) DIVERGENCE = GFS 850 hPa Horizontal Divergence (x10-7 s-1) VORTICITY = GFS 850 hPa Vorticity (x10-6 s-1) VERTICAL SHEAR = GFS 200-850 hPa Vertical Shear (kt) RH = GFS 600-850 hPa Relative Humidity (%) GOES = GOES Water Vapor Pixels Colder than -40C (%) DVORAK = Dvorak T-number, source: TAFB Version 3.0, July 2018