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Tropical Storm Joyce Forecast Discussion Number 12
2018-09-15 16:32:04| National Hurricane Center (Atlantic)
Issued at 1100 AM AST Sat Sep 15 2018 377 WTNT45 KNHC 151432 TCDAT5 Tropical Storm Joyce Discussion Number 12 NWS National Hurricane Center Miami FL AL102018 1100 AM AST Sat Sep 15 2018 Joyce is feeling the effects of shear this morning. The low-level center of the tropical storm has become exposed to the south of a area of deep convection. ASCAT data indicate the the maximum winds have dropped to 35-40 kt, and 40 kt is chosen as the initial wind speed since the resolution of ASCAT is likely causing an undersampling of the small storm. The environment isn't forecast to change much near Joyce during the next day or so, with strong shear being offset by waters near 27C. The NHC forecast is leveled off during that time, a bit lower than the previous prediction mostly to account for the initial wind speed. Thereafter, while the shear is forecast to continue, the mid-level air should become drier near the center, and SSTs cool off gradually below 26C. These conditions should cause Joyce to slowly weaken early next week, and dissipate in 3 days or so. This is the solution provided by much of the guidance, and the NHC forecast follows suit. Joyce has accelerated overnight, now moving east-northeastward at about 12 kt. The storm remains embedded in the same trough as Tropical Storm Helene and it should follow that tropical cyclone east-northeastward to northeastward at increasing forward speeds during the next day or two. Beyond that time, as Joyce becomes a shallow cyclone, it is forecast to turn southeastward due to low-level flow around the eastern side of a building ridge over the central Atlantic Ocean. No significant changes were made to the forecast, which lies on the southern side of the guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 15/1500Z 32.0N 41.0W 40 KT 45 MPH 12H 16/0000Z 32.9N 39.2W 40 KT 45 MPH 24H 16/1200Z 34.0N 35.9W 40 KT 45 MPH 36H 17/0000Z 34.5N 32.2W 35 KT 40 MPH 48H 17/1200Z 34.0N 29.0W 30 KT 35 MPH 72H 18/1200Z 32.0N 25.5W 25 KT 30 MPH 96H 19/1200Z...DISSIPATED $$ Forecaster Blake
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