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Tropical Storm Josephine Forecast Discussion Number 17
2020-08-15 22:34:51| National Hurricane Center (Atlantic)
Issued at 500 PM AST Sat Aug 15 2020 889 WTNT41 KNHC 152034 TCDAT1 Tropical Storm Josephine Discussion Number 17 NWS National Hurricane Center Miami FL AL112020 500 PM AST Sat Aug 15 2020 Josephine continues to feel the effects of westerly shear, and the low cloud swirl denoting the center is partly exposed at the western edge of the convection. Satellite intensity estimates have not changed significantly since the earlier recon flight, so the initial intensity remains 40 kt. Animation of satellite imagery suggests that the low-level circulation is at best barely closed, but there is insufficient evidence right now to justify a downgrade to a tropical wave. Another aircraft is scheduled to investigate the system near 0000Z. The initial motion is west-northwestward or 295/15 kt. It sounds like a broken record, but there is little change to either the forecast guidance or the forecast track since the last advisory. For the next 36-48 h, Josephine or its remnants are likely to continue to move west-northwestward on the southwest side of the subtropical ridge. After that, the system is forecast to recurve to the north and north-northeast through a break in the western portion of the ridge. As before, the new NHC forecast lies near the the center of the tightly-clustered guidance and near the various consensus models. Josephine is expected to remain in an environment of moderate to strong westerly shear for at least the next 48-60 h which should cause the system to weaken. The intensity forecast, which assumes some sort of closed circulation will last for 5 days, now calls for the system to weaken to a depression between 24-36 h and become a remnant low by 60 h. An alternative scenario is that the system degenerates to a tropical wave, which could occur at almost any time given the state of the circulation. There is a chance that Josephine or its remnants could encounter a less hostile environment after 72 h. However, it remains unclear at this time whether there will be enough left of the system to take advantage of those 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 15/2100Z 20.0N 61.6W 40 KT 45 MPH 12H 16/0600Z 20.8N 63.4W 35 KT 40 MPH 24H 16/1800Z 22.1N 65.5W 35 KT 40 MPH 36H 17/0600Z 23.4N 67.4W 30 KT 35 MPH 48H 17/1800Z 24.9N 68.6W 30 KT 35 MPH 60H 18/0600Z 26.3N 69.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 18/1800Z 28.0N 69.4W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 19/1800Z 30.5N 68.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 20/1800Z 33.0N 65.0W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Beven
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