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| #1143663 (Received by flhurricane at: 4:54 PM 14.Jul.2023) TCDAT5 Subtropical Storm Don Discussion Number 3 NWS National Hurricane Center Miami FL AL052023 500 PM AST Fri Jul 14 2023 Don is producing two broken bands of convection which are displaced to the east of the low-level center. The cyclone still leans heavily on the subtropical side of the spectrum, lacking a central dense overcast, being associated with an upper-level low, and having an asymmetric distribution of convection. However, this morning`s ASCAT data did indicate that the radius of maximum winds had contracted down to 30 n mi, more akin to a tropical cyclone. Based on the earlier ASCAT data and an Hebert-Poteat classification of ST2.5 from TAFB, the initial intensity remains 40 kt. Don deviated to the left of the previous forecast track during the past few hours and is estimated to be moving northwestward, or 325/7 kt. Despite that, the track forecast reasoning is unchanged. An eastern Atlantic mid-level ridge will be the main steering influence and is expected to migrate westward across the Atlantic during the next several days. Don is forecast to move around the northern and eastern side of the ridge, turning northward, eastward, and then southward over the next 5 days. The new NHC track forecast has been shifted a bit westward, mainly due to the recent deviation to the west, and is close to a blend of the TVCA and FSSE consensus aids. Subsidence behind the trough is causing dry air to be entrained into Don`s circulation, and the storm is currently over waters of 25-26 degrees Celsius. The forecast track takes Don over waters as cold as 23 degrees in about 3 days, and simulated satellite imagery from the GFS and ECMWF suggests that the convective coverage and pattern could be quite degraded by that time. Still, the intensity guidance is in relatively good agreement that Don will only weaken a bit during the next several days, with some possible restrengthening by the end of the forecast period when the storm again reaches warmer waters. For continuity`s sake, the forecast continues to show Don maintaining subtropical storm status for the next 5 days, but it could become post-tropical at any time if the convection wanes and loses organization. FORECAST POSITIONS AND MAX WINDS INIT 14/2100Z 34.1N 48.0W 40 KT 45 MPH 12H 15/0600Z 35.1N 48.3W 40 KT 45 MPH 24H 15/1800Z 36.5N 48.7W 40 KT 45 MPH 36H 16/0600Z 37.8N 48.6W 35 KT 40 MPH 48H 16/1800Z 38.7N 47.7W 35 KT 40 MPH 60H 17/0600Z 38.7N 45.8W 35 KT 40 MPH 72H 17/1800Z 37.9N 43.7W 35 KT 40 MPH 96H 18/1800Z 35.0N 40.7W 35 KT 40 MPH 120H 19/1800Z 33.0N 40.6W 40 KT 45 MPH $$ Forecaster Berg |
