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| #1012434 (Received by flhurricane at: 10:42 PM 15.Aug.2020) TCDAT1 Tropical Storm Josephine Discussion Number 18 NWS National Hurricane Center Miami FL AL112020 1100 PM AST Sat Aug 15 2020 An Air Force Reserve reconnaissance aircraft investigating Josephine this evening manages to find a barely close low-level circulation center that was displaced about 90 nmi to the west of the edge of the southernmost burst of deep convection. Maximum flight-level and surface were likely missed since the aircraft did not fly through the strongest convection. Thus, the intensity is being maintained at 40 kt based on continuity and a blend of subjective and objective satellite classifications. The initial motion is west-northwestward or an uncertain 300/13 kt. Due to Josephine`s severely sheared state, the system could open up into a sharp tropical wave at any time during the next 36 hours, which complicates determining a forecast track. For now, it will be assumed that there will be some identifiable low-level vorticity feature that will serve as a proxy center for Josephine or its remnants, which are forecast to continue to move west-northwestward along the southwestern periphery of a deep-layer subtropical ridge. Thereafter, the cyclone is expected to recurve to the north and north-northeast through a break in the ridge that is forecast to develop southwest of Bermuda in 48 hours or so, with at least the remnants passing near Bermuda in about 120 hours. The NHC official forecast track lies close to the previous advisory track and the tightly-clustered simple- and corrected-consensus models. Josephine is expected to remain in an environment of moderate to strong westerly shear for at least the next 48-60 h, followed by sharply decreasing shear conditions thereafter. For the next two days or so, however, Josephine is forecast to weaken owing to the strong shear conditions and surrounding dry mid-level air, with the possibility of the tropical storm degenerating into an open wave at any time. If the remnant vorticity can manage to remain intact through a deep enough layer of the troposphere, then some regeneration could occur in the 72-120 hour time when the vertical shear/mid-level moisture are forecast to decrease/increase significantly. However, it still remains unclear at this time whether there will be enough remnant circulation to take advantage of those more favorable conditions. KEY MESSAGES: 1. Josephine is passing far enough to the northeast of the Leeward Islands to prevent major impacts. However, interests there should continue to monitor its progress until the storm has passed north of that area. 2. Locally heavy rainfall is possible in the northern Leeward Islands, the Virgin Islands, and Puerto Rico as Josephine passes by to the northeast. Isolated minor flooding is possible in Puerto Rico through Monday. FORECAST POSITIONS AND MAX WINDS INIT 16/0300Z 20.1N 62.6W 40 KT 45 MPH 12H 16/1200Z 21.0N 64.3W 35 KT 40 MPH 24H 17/0000Z 22.3N 66.3W 35 KT 40 MPH 36H 17/1200Z 23.7N 67.9W 30 KT 35 MPH 48H 18/0000Z 25.1N 68.8W 30 KT 35 MPH 60H 18/1200Z 27.1N 68.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 19/0000Z 29.0N 68.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 20/0000Z 30.6N 67.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 21/0000Z 32.8N 64.1W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Stewart |
