Issued at 500 PM AST Mon Aug 04 2025
ZCZC MIATCDAT4 ALL TTAA00 KNHC DDHHMM Tropical Storm Dexter Discussion Number 4 NWS National Hurricane Center Miami FL AL042025 500 PM AST Mon Aug 04 2025 There is not a lot new to report with Dexter this afternoon. The center remains partially exposed, with periodic bursts of deep convection firing off along the downshear-right side of the storm. This activity continues to struggle rotating upshear due to westerly vertical wind shear which has now increased above 20 kt. The 18 UTC Dvorak estimates from TAFB and SAB were T3.0/45 kt and T2.0/30 kt respectively. Objective intensity estimates also range from 35 to 45 kt. Earlier scatterometer data received after the prior advisory only had a peak value of 33 kt. The initial intensity remains 40 kt for this advisory, a blend of all the various intensity estimates. There are several mesovorticies rotating around the mean center, but Dexter in general remains on a northeastward heading at 050/13 kt. A narrow mid-level ridge oriented northeast to southwest from the Azores to Bermuda should enable Dexter to continue moving northeastward to east-northeastward, as long as it remains vertically coherent. The vertical depth likely plays a role in Dexter's future forward motion, with significant along-track spread persisting in the track guidance this afternoon. The NHC track forecast is on the faster side of the guidance envelope, close to the most recent 12 UTC ECMWF forecast track. However, it remains possible that Dexter completely decouples from its mid-level circulation and misses phasing with the trough digging southward from Atlantic Canada. Instead of accelerating northeastward, this latter scenario could result in the storm slowing down as it becomes a shallow cyclone. For now, the latest NHC track forecast is close to the prior one. As shear continue to increase over the tropical cyclone, forecasted to be above 30 kt in 12 h, its window for further tropical intensification is closing. The intensity guidance is a bit lower this afternoon. In response, the NHC intensity forecast now holds Dexter at 40 kt until it undergoes extratropical transition sometime between 60-72 h, where a slight amount of intensification is still shown. The intensity forecast is in the middle of the guidance envelope. As mentioned previously, Dexter's final structure remains quite uncertain near the end of the forecast period, and it is entirely possible the storm could become a remnant low instead of an extratropical cyclone by the latter half of this week. FORECAST POSITIONS AND MAX WINDS INIT 04/2100Z 36.1N 66.2W 40 KT 45 MPH 12H 05/0600Z 37.1N 64.5W 40 KT 45 MPH 24H 05/1800Z 38.2N 62.5W 40 KT 45 MPH 36H 06/0600Z 39.2N 60.3W 40 KT 45 MPH 48H 06/1800Z 39.8N 57.5W 40 KT 45 MPH 60H 07/0600Z 40.7N 53.2W 40 KT 45 MPH 72H 07/1800Z 42.5N 48.2W 45 KT 50 MPH...POST-TROP/EXTRATROP 96H 08/1800Z 45.0N 41.4W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 09/1800Z 48.2N 29.9W 40 KT 45 MPH...POST-TROP/EXTRATROP $$ Forecaster Papin NNNN