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Tropical Storm Oscar Forecast Discussion Number 7
2018-10-28 15:50:41| National Hurricane Center (Atlantic)
Issued at 1100 AM AST Sun Oct 28 2018 000 WTNT41 KNHC 281450 TCDAT1 Tropical Storm Oscar Discussion Number 7 NWS National Hurricane Center Miami FL AL162018 1100 AM AST Sun Oct 28 2018 Deep convection has redeveloped near the center of Oscar since early this morning and its low-level center is no longer exposed. Satellite intensity estimates have not changed since last night and the estimated intensity of 60 kt is above the various techniques. The initial intensity estimate is based primarily on the latest available ASCAT data from last night around 0100 UTC that showed maximum winds of 55-60 kt. Given the recent increase in convection observed near the center of Oscar, it seems unlikely that the winds have decreased since that time. It is worth noting that the small inner-core of Oscar increases the uncertainty of the intensity estimate, and could make the cyclone susceptible to short term intensity fluctuations that are nearly impossible to forecast or precisely detect. Virtually no change has been made to the intensity forecast. The tropical storm is moving over sufficiently warm water to support intensification and it is located within a light to moderate shear environment. All the intensity models forecast at least some strengthening, and Oscar is expected to become a hurricane later today or tonight, with some additional strengthening possible through Wednesday. Extratropical transition is forecast to begin soon thereafter, which will likely result in a decrease in the maximum winds, even as the extent of tropical-storm-force winds rapidly increases. This process is expected to be complete by 120 h. The new NHC intensity forecast is very close to the intensity consensus IVCN at all forecast hours. Oscar turned abruptly westward earlier this morning, and the initial motion estimate is now 270/10 kt. The tropical cyclone is forecast to continue moving generally westward for another 12 to 24 h on the south side of a mid-layer ridge over the northern central Atlantic. Oscar should then turn toward the north between the ridge and a mid-latitude trough approaching from the west. By Wednesday, the cyclone is expected to accelerate north-northeastward or northeastward as it becomes embedded in deep-layer southwesterly flow ahead of the aforementioned trough. All of the global models agree on this general scenario, though there are differences regarding the exact timing that Oscar will begin its recurvature and how quickly it will accelerate across the northern Atlantic. That said, the track consensus aids have changed very little, and no significant changes were made to the previous track forecast. FORECAST POSITIONS AND MAX WINDS INIT 28/1500Z 25.5N 53.8W 60 KT 70 MPH 12H 29/0000Z 25.6N 55.8W 65 KT 75 MPH 24H 29/1200Z 26.2N 57.8W 65 KT 75 MPH 36H 30/0000Z 27.3N 58.4W 70 KT 80 MPH 48H 30/1200Z 29.3N 57.8W 75 KT 85 MPH 72H 31/1200Z 37.1N 51.3W 80 KT 90 MPH 96H 01/1200Z 45.5N 40.0W 65 KT 75 MPH 120H 02/1200Z 53.0N 22.0W 55 KT 65 MPH...POST-TROP/EXTRATROP $$ Forecaster Zelinsky
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