Issued at 1100 PM AST Mon Oct 02 2023
360 WTNT42 KNHC 030245 TCDAT2 Tropical Storm Philippe Discussion Number 39 NWS National Hurricane Center Miami FL AL172023 1100 PM AST Mon Oct 02 2023 Philippe continues to be under the influence of significant westerly to northwesterly vertical wind shear. The center, which is located on the northwestern edge of the main area of deep convection, recently passed over Barbuda. Most of the stronger convection is over the southern and southeastern portions of the circulation, so the Leeward Islands should continue to experience strong winds and heavy rains even when the center of the storm begins to move north of those islands. The current intensity is kept at 45 kt based on SFMR-observed surface winds from an Air Force Hurricane Hunter aircraft that is still investigating the system. The cyclone has wobbled west-northwestward this evening and the current motion estimate is 300/6 kt. Over the next few days, Philippe should move along the western periphery of a mid-level subtropical high pressure area. Most of the guidance model tracks have shifted even farther west, with the exception of the GFS deterministic and ensemble mean forecasts, which appear to be eastern outliers at this time. Based the new dynamical model consensus, the official forecast track is, again, shifted farther west from the previous one. Later in the forecast period, the spread in the guidance models increases. Notably,the GFS prediction shows that a mid-tropospheric trough over the northwestern Atlantic fails to capture the cyclone and take it northward into Atlantic Canada, but keeps Philippe moving slowly over the subtropical Atlantic at 5 days and even beyond. Little change in intensity is likely for the next couple of days while the storm remains in an environment of strong vertical wind shear. In 2 to 3 days, the global models suggest that Philippe could encounter a more favorable upper-tropospheric wind environment, with more anticyclonic and diffluent upper-level winds evolving over the system. Therefore, some strengthening is predicted in the latter half of the forecast period. The official intensity forecast is near the high end of the model guidance, however. KEY MESSAGES: 1. Tropical storm conditions are expected across Barbuda and Antigua tonight while Philippe passes just north of the area. Interests elsewhere in the northern Leeward Islands should continue to monitor this system. 2. Heavy rainfall from Philippe is expected to produce scattered flash flooding across portions of the Leeward and northern Windward Islands, particularly between Barbuda and Dominica, into early Wednesday. FORECAST POSITIONS AND MAX WINDS INIT 03/0300Z 17.8N 62.1W 45 KT 50 MPH 12H 03/1200Z 18.4N 62.8W 45 KT 50 MPH 24H 04/0000Z 19.7N 63.4W 45 KT 50 MPH 36H 04/1200Z 21.3N 64.0W 45 KT 50 MPH 48H 05/0000Z 23.0N 64.4W 45 KT 50 MPH 60H 05/1200Z 24.8N 64.7W 50 KT 60 MPH 72H 06/0000Z 26.9N 64.3W 55 KT 65 MPH 96H 07/0000Z 31.6N 62.8W 60 KT 70 MPH 120H 08/0000Z 36.0N 60.0W 60 KT 70 MPH $$ Forecaster Pasch