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| #1144436 (Received by flhurricane at: 5:03 PM 19.Jul.2023) TCDAT5 Tropical Storm Don Discussion Number 23 NWS National Hurricane Center Miami FL AL052023 900 PM GMT Wed Jul 19 2023 Don has continued to become better organized during the day, with a deep convective band now curving more than halfway around the center, and an expanding outflow pattern especially southeast of the storm. While the western side of the circulation still has a lot of dry air lurking, it seems like the lack of shear is allowing the core of the cyclone to develop. Dvorak estimates have increased, and a blend of the latest data gives an initial wind speed of 40 kt. Scatterometer has missed the core for about the past day, so hopefully tonight`s passes will validate the improving satellite presentation. Further intensification is likely for the next day or so while Don moves over a local maximum in sea-surface temperatures (SSTs) with light shear. Thereafter, the environment becomes less conducive with cooling SSTs, drier environmental air, and perhaps an increase in shear. The forecast is kept steady through the end of the work week, then some weakening while Don crosses its own cool wake. The NHC wind speed prediction is bumped up from the last one, consistent with the latest model consensus, and most of the guidance is in pretty good agreement on this scenario. The storm should lose all of its deep convection and become post-tropical late Sunday or on Monday after it crosses north of the Gulf Stream. Don has turned westward, now moving a bit faster at 7 kt. The system should turn west-northwestward tomorrow as it moves beneath a large blocking ridge over the north-central Atlantic, with no changes to the forecast in the short term. However, there has been a pretty significant synoptic pattern shift in the models by Friday with the blocking ridge much slower to depart, resulting in Don moving more to the northwest and not accelerating as quickly northeastward. The new forecast follows the guidance trend, but for continuity concerns, the forecast is still faster than most of the guidance, and further changes will likely be required on the next advisory. FORECAST POSITIONS AND MAX WINDS INIT 19/2100Z 33.8N 40.3W 40 KT 45 MPH 12H 20/0600Z 33.7N 41.3W 45 KT 50 MPH 24H 20/1800Z 34.1N 42.7W 50 KT 60 MPH 36H 21/0600Z 34.8N 44.3W 50 KT 60 MPH 48H 21/1800Z 35.9N 46.1W 50 KT 60 MPH 60H 22/0600Z 37.2N 47.6W 45 KT 50 MPH 72H 22/1800Z 39.0N 48.6W 45 KT 50 MPH 96H 23/1800Z 43.0N 48.0W 45 KT 50 MPH 120H 24/1800Z 45.5N 44.0W 35 KT 40 MPH...POST-TROPICAL $$ Forecaster Blake |
