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| #1155534 (Received by flhurricane at: 4:50 AM 02.Oct.2023) TCDAT2 Tropical Storm Philippe Discussion Number 36 NWS National Hurricane Center Miami FL AL172023 500 AM AST Mon Oct 02 2023 The overall structure of Philippe has changed very little during the past day or so. Deep convection remains confined to the southeastern portion of the circulation due to moderate to strong northwesterly vertical wind shear. There is no significant banding features, but the cloud tops within the main convective mass are quite cold. Radar imagery from Barbados shows very heavy rainfall is occurring just east of the Lesser Antilles. The initial intensity is held at 45 kt in deference to the earlier aircraft data, and the latest subjective Dvorak intensity estimates which are unchanged from before. The next Air Force Reserve reconnaissance aircraft mission is scheduled to investigate Philippe later this morning. Center fixes during the past 6-12 hours indicate that Philippe has turned northwestward (315 degrees) and is moving a little faster, around 6 kt. Philippe is forecast to move around the southwestern portion of a mid-level ridge over the subtropical Atlantic during the next couple of days. After that time, Philippe should turn northward between the aforementioned ridge and a mid- to upper-level trough over the southwestern Atlantic. Around day 5, there is increasing uncertainty as to whether Philippe will turn east-northeastward or continue on a more northerly trajectory ahead of a large trough moving into the eastern United States. Little change was made to the previous forecast through 72 hours, but after that time the track was adjusted northwestward closer to the GFS ensemble mean. The new track is not as far west as the latest ECMWF or the multi-model consensus aids. Strong westerly vertical wind shear is expected to prevent significant strengthening for about another 12-24 hours. After that time, Philippe is expected to encounter a more favorable upper-level wind pattern as it moves northward over the Atlantic. This should allow for steady strengthening, and much of the guidance predicts that Philippe will become a hurricane in 3 to 4 days. The NHC intensity forecast follows suit, and is a blend of the HFIP corrected consensus model and the multi-model (ICVN) intensity aid. KEY MESSAGES: 1. Tropical storm conditions are possible across portions of the northern Leeward Islands through tonight while Philippe passes near or just northeast of the area, and a Tropical Storm Watch is in effect for Antigua and Barbuda. Interests elsewhere in the northern Leeward Islands should continue to monitor this system. 2. Heavy rainfall from Philippe could produce isolated to scattered flash flooding, particularly across Barbuda and Antigua, through Tuesday. FORECAST POSITIONS AND MAX WINDS INIT 02/0900Z 17.1N 60.0W 45 KT 50 MPH 12H 02/1800Z 17.7N 60.7W 45 KT 50 MPH 24H 03/0600Z 18.6N 61.4W 45 KT 50 MPH 36H 03/1800Z 19.8N 61.8W 50 KT 60 MPH 48H 04/0600Z 21.2N 62.2W 50 KT 60 MPH 60H 04/1800Z 22.7N 62.3W 55 KT 65 MPH 72H 05/0600Z 24.6N 62.2W 60 KT 70 MPH 96H 06/0600Z 28.3N 60.8W 70 KT 80 MPH 120H 07/0600Z 31.7N 58.9W 75 KT 85 MPH $$ Forecaster Brown |
