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| #980917 (Received by flhurricane at: 11:09 AM 04.Sep.2019) TCDAT3 Tropical Storm Gabrielle Discussion Number 4 NWS National Hurricane Center Miami FL AL082019 1100 AM AST Wed Sep 04 2019 Gabrielle appears better organized on satellite imagery this morning with the low-level center moving a little more underneath the convection. In addition, a large curved band has become better defined in the northern semicircle. The initial wind speed is increased to 45 kt, which is consistent with a just-received ASCAT-C pass of 40-45 kt. The initial motion estimate is 320/8. For the next 5 days, Gabrielle is forecast to move generally northwestward toward a break in the Bermuda-Azores high pressure ridge located between 40W-50W longitude. An increase in forward speed in a few days is expected due to the gradient between an upper-level low to the west and the ridge to the northeast. The official forecast track lies slightly to the east of the previous forecast in the short term, and then is very close to the previous NHC track in days 3 to 5. Gabrielle is expected to remain in a marginal environment during the next 2 to 3 days, with moderate southerly to southwesterly wind shear, low values of mid-level relative humidity and SSTs near 26-27C. No change in wind speed is predicted during the first two days. Thereafter, some strengthening is possible as Gabrielle moves on the northeast side of the upper-level low concurrent with the cyclone moving over warmer water. This is a typical situation for intensification, so the forecast wind speed is raised slightly at days 4-5. The intensity forecast is fairly consistent with the bulk of the typically reliable intensity models. FORECAST POSITIONS AND MAX WINDS INIT 04/1500Z 20.5N 33.8W 45 KT 50 MPH 12H 05/0000Z 21.0N 34.5W 45 KT 50 MPH 24H 05/1200Z 21.9N 35.6W 45 KT 50 MPH 36H 06/0000Z 23.1N 36.9W 45 KT 50 MPH 48H 06/1200Z 24.6N 38.4W 45 KT 50 MPH 72H 07/1200Z 28.6N 41.7W 50 KT 60 MPH 96H 08/1200Z 32.5N 45.5W 55 KT 65 MPH 120H 09/1200Z 36.5N 47.5W 55 KT 65 MPH $$ Forecaster Blake/Hagen |
