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#980973 (Received by flhurricane at: 4:45 PM 04.Sep.2019) TCDAT3 Tropical Storm Gabrielle Discussion Number 5 NWS National Hurricane Center Miami FL AL082019 500 PM AST Wed Sep 04 2019 Recent microwave data suggest that Gabrielle continues to gradually become better organized, and the last few GOES-16 images show a convective burst forming over the center. The initial intensity is estimated at 45 kt based on the Dvorak number from TAFB and an earlier ASCAT pass from this morning, but it`s possible that this intensity estimate may be conservative. The storm could intensify a little more in the short-term, but overall it is expected to remain in a marginal environment during the next couple of days, characterized by moderate southerly to southwesterly wind shear, low values of mid-level relative humidity and SSTs near 26-27C. Little overall change in strength is predicted during the next two days. Thereafter, some strengthening is likely as Gabrielle moves on the northeastern side of an upper-level low into a lower shear region, at the same time the cyclone moves over warmer water. The new NHC intensity forecast shows Gabrielle reaching hurricane strength in about 5 days, which is consistent with the latest HWRF, NOAA corrected-consensus and COAMPS-TC models. The initial motion is estimated at 325/8. For the next 5 days, Gabrielle is forecast to move generally northwestward toward a break in the Bermuda-Azores high pressure ridge. An increase in forward speed is expected due to the gradient between an upper-level low to the west and the ridge to the northeast. The latest models have shifted a little to the west for the point of recurvature in about 5 days, and the official forecast splits the difference between the previous NHC forecast and the latest various consensus models in the day 4 to 5 time period. FORECAST POSITIONS AND MAX WINDS INIT 04/2100Z 21.0N 34.0W 45 KT 50 MPH 12H 05/0600Z 21.7N 34.6W 50 KT 60 MPH 24H 05/1800Z 22.8N 35.8W 50 KT 60 MPH 36H 06/0600Z 24.2N 37.4W 45 KT 50 MPH 48H 06/1800Z 26.1N 39.1W 45 KT 50 MPH 72H 07/1800Z 30.0N 43.2W 50 KT 60 MPH 96H 08/1800Z 33.0N 47.5W 55 KT 65 MPH 120H 09/1800Z 36.5N 48.5W 65 KT 75 MPH $$ Forecaster Blake/Hagen |