* ATLANTIC TC GENESIS INDEX * * GFS VERSION * * AL172020 09/20/20 18 UTC * TIME (hr) 0 6 12 18 24 36 48 60 72 84 96 108 120 Prob of Genesis 17% 33% LAT (deg N) 36.7 36.4 36.1 35.6 35.0 34.2 33.8 33.4 33.6 34.0 33.8 32.6 31.7 LON (deg W) 27.3 27.5 27.4 27.1 26.3 23.4 20.1 17.7 15.7 15.3 16.8 19.9 24.2 DTL (km) 1610 1635 1635 1583 1487 1210 944 750 578 561 682 841 1144 TRACK SOURCE TABM TABM TABM TABM TABM TABM TABM TABM TABM TABM TABM TABM TABM TCGI 0-48h Genesis Forecast: 17% is 0.6 times the sample mean ( 30%) TCGI 0-120h Genesis Forecast: 33% is 0.8 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 0.4 2.5% 1.0 0.9 4.8% VORTICITY 1.7 2.8 6.3% 1.4 2.3 14.2% VERTICAL SHEAR 16.3 18.6 7.3% 18.4 18.2 12.3% RH 73.1 50.4 0.0% 70.9 53.7 0.7% GOES 29.1 0.0 0.0% 29.3 0.0 0.0% DVORAK 0.8 0.5 0.9% 0.8 0.5 1.2% --------------------------------------------------------------------------------------------- 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