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Tropical Depression Eleven Forecast Discussion Number 2
2018-09-22 10:36:22| National Hurricane Center (Atlantic)
Issued at 500 AM AST Sat Sep 22 2018 624 WTNT41 KNHC 220836 TCDAT1 Tropical Depression Eleven Discussion Number 2 NWS National Hurricane Center Miami FL AL112018 500 AM AST Sat Sep 22 2018 Deep convection remains displaced to the east of the depression's center due to 30-40 kt of westerly shear. Although Dvorak final-T numbers from TAFB and SAB have decreased since yesterday--now a consensus T1.0--the initial intensity is held, perhaps generously, at 30 kt. Strong westerly shear is expected to persist for several days, which at the very least will prevent the depression from getting any better organized. Since the global models show the depression opening up into a trough in about 24 hours, the new NHC intensity forecast brings down the winds a little faster, shows the system becoming a remnant low by 36 hours, and dissipates the low entirely by 48 hours well east of the Windward Islands. This evolution could certainly occur more quickly than indicated by the official forecast. The center of the depression has not been moving much, and it's possible the sheared convection is trying to pull it back toward the east. However, the average motion over the past 12 hours is westward, or 270/4 kt. The track guidance insists that the depression should move slowly west-northwestward over the next couple of days, but given that the system has not made any northward progress, I elected to skirt the southern edge of the guidance envelope. This new forecast is a little south of the previous NHC track prediction. FORECAST POSITIONS AND MAX WINDS INIT 22/0900Z 13.0N 53.5W 30 KT 35 MPH 12H 22/1800Z 13.3N 54.3W 30 KT 35 MPH 24H 23/0600Z 13.6N 55.4W 25 KT 30 MPH 36H 23/1800Z 13.8N 56.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 24/0600Z...DISSIPATED $$ Forecaster Berg
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