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Subtropical Storm Oscar Forecast Discussion Number 4
2018-10-27 22:33:01| National Hurricane Center (Atlantic)
Issued at 500 PM AST Sat Oct 27 2018 000 WTNT41 KNHC 272032 TCDAT1 Subtropical Storm Oscar Discussion Number 4 NWS National Hurricane Center Miami FL AL162018 500 PM AST Sat Oct 27 2018 Oscar is still located beneath an upper-level low, however it its convective structure is now more reminiscent of a tropical cyclone. Deep convection is primarily occuring in a small burst just south of the center of Oscar, however this convective activity appears to be displaced by light northerly shear associated with the upper-low. Earlier AMSU sounding data indicated that the cyclone has developed a weak but vertically deep warm core which also indicates that Oscar is nearly a tropical cyclone, if it isn't one already. Oscar is moving quickly westward away from the upper-low, and will likely become a tropical storm later tonight if its current structural trends continue. The initial intensity is held at 50 kt, based primarily on the latest Hebert-Poteat subtropical intensity estimate from TAFB. The intensity guidance has bounced back, and the most of the intensity guidance is higher than it was six hours ago. While little change was made to the NHC intensity forecast, it now lies very near the intensity consensus at all forecast hours. Gradual intensification is still expected and Oscar is forecast to approach hurricane strength by Monday. Slight additional intensification is possible through the middle of next week, until extratropical transition occurs by 120 h. Oscar moved very quickly westward this afternoon, but a more representative motion estimate is 265/15 kt. The latest runs of the typically reliable global models are in better agreement than they were this morning. Oscar is forecast to move west-southwestward or westward for the next day or two on the south side of a mid-level ridge to the north. The cyclone is then expected to recurve and accelerate northeastward ahead of a substantial mid-latitude trough moving across the western and central Atlantic by the middle of next week. The official track forecast has been adjusted westward to bring it closer to the latest track consensus, especially for the first 72 h of the forecast. By day 5, the official forecast is quite similar to the previous advisory, but with a slightly slower forward speed for Oscar. FORECAST POSITIONS AND MAX WINDS INIT 27/2100Z 26.9N 50.7W 50 KT 60 MPH 12H 28/0600Z 26.1N 53.0W 50 KT 60 MPH...TROPICAL CYCLONE 24H 28/1800Z 25.7N 55.8W 55 KT 65 MPH 36H 29/0600Z 25.6N 57.9W 55 KT 65 MPH 48H 29/1800Z 26.4N 59.1W 60 KT 70 MPH 72H 30/1800Z 30.6N 57.5W 70 KT 80 MPH 96H 31/1800Z 38.5N 50.0W 70 KT 80 MPH 120H 01/1800Z 46.5N 38.0W 60 KT 70 MPH...POST-TROP/EXTRATROP $$ Forecaster Zelinsky
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