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| #1240234 (Received by flhurricane at: 10:48 PM 03.Aug.2025) TCDAT4 Tropical Storm Dexter Discussion Number 1 NWS National Hurricane Center Miami FL AL042025 1100 PM AST Sun Aug 03 2025 The area of low pressure located several hundred miles off the coast of North Carolina has been producing persistent deep convection for much of the day, and it appears to have separated from the frontal zone from which it formed. Although surface troughing still extends northeast and southwest of the low itself, model analyses show that the low is now located southeast of the strongest temperature and moisture gradients, indicating that it is no longer frontal and has made the transition to a tropical storm. The low-level center is located on the southwestern edge of the deep convection due to moderate southwesterly shear. Maximum winds are estimated to be 40 kt based on a very recent ASCAT pass, and the cyclone is therefore being designated as Tropical Storm Dexter. The initial motion is east-northeastward, or 070/10 kt, with Dexter embedded within mid-latitude westerly flow on the northwestern side of the subtropical ridge. Remaining north of the ridge, Dexter is expected to move on a northeasterly or east-northeasterly trajectory for the next 3-4 days. While there is not much cross-track spread among the guidance, there are some speed differences, most notably with the GFS showing Dexter getting trapped beneath the ridge and meandering for a couple of days. The NHC track forecast goes with the more progressive solution, and is closest to the HCCA and GDM ensemble mean. The moderate shear currently affecting Dexter is expected to increase to over 20 kt in 12-24 hours, and then to about 30 kt in 36-48 hours. As a result, not much strengthening is anticipated. Much of the intensity guidance shows a fairly steady intensity between 40-50 kt through 72 hours, and the NHC forecast therefore takes the middle of the road and shows a peak of 45 kt. Dexter is likely to be post-tropical by 60 hours, if not sooner, as the stronger shear strips the storm's convection away. The bulk of the global models suggest it could then become extratropical again by day 4 and then be absorbed by a front by day 5, but there is a lot of uncertainty in that forecast. FORECAST POSITIONS AND MAX WINDS INIT 04/0300Z 34.3N 69.4W 40 KT 45 MPH 12H 04/1200Z 35.1N 67.7W 45 KT 50 MPH 24H 05/0000Z 36.4N 65.3W 45 KT 50 MPH 36H 05/1200Z 37.7N 63.1W 45 KT 50 MPH 48H 06/0000Z 38.5N 61.3W 45 KT 50 MPH 60H 06/1200Z 39.0N 59.3W 45 KT 50 MPH...POST-TROPICAL 72H 07/0000Z 39.3N 56.9W 40 KT 45 MPH...POST-TROPICAL 96H 08/0000Z 40.5N 50.8W 35 KT 40 MPH...POST-TROP/EXTRATROP 120H 09/0000Z...DISSIPATED $$ Forecaster Berg |
