|
Show Selection: |
| #1155494 (Received by flhurricane at: 10:41 PM 01.Oct.2023) TCDAT2 Tropical Storm Philippe Discussion Number 35 NWS National Hurricane Center Miami FL AL172023 1100 PM AST Sun Oct 01 2023 Philippe`s cloud pattern has not become significantly better organized since earlier today. The system is still producing very deep convection with cloud tops to -80 deg C or colder mainly over the southeastern quadrant of the circulation. There are no obvious curved convective banding features at this time. Some new thunderstorms have developed near and over the center and this was noted by the Air Force Hurricane Hunters who have been investigating the storm this evening. Observations from the aircraft indicate little change in strength, with peak SFMR-observed surface winds near 45 kt. The tropical cyclone has moved rather slowly over the past several hours and the initial motion estimate is west-northwestward, or 300/4 kt. Philippe should turn northwestward to northward along the western periphery of a mid-level high pressure area for the next few days. Then, the system should turn north-northeastward and move through a weakness in the ridge. The track guidance through 48 hours has shifted eastward on this cycle. In an attempt to maintain continuity from the previous forecasts, the NHC track is not shifted eastward as much as shown by the model consensus, and the change through 24 hours is fairly slight. Late in the forecast period, there is uncertainty as to how soon the cyclone will move into the higher-latitude westerlies. The new GFS model run suggests that the system may turn eastward and stay in the subtropics through 5 days. If this turns out to be true, then Philippe could have a prolonged existence. The environment for Philippe in the short term does not appear conducive for significant strengthening, with fairly strong westerly vertical wind shear likely to continue to affect the system through Monday. When the system moves farther north over the Atlantic, it may encounter a region of reduced shear as indicated by some of the dynamical guidance. The official forecast still shows the system becoming a hurricane in the 3- to 5-day time frame and this is also supported by the IVCN model intensity guidance. KEY MESSAGES: 1. Tropical storm conditions are possible across portions of the northern Leeward Islands Monday and Monday night 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 as additional watches or warnings could be required later tonight or Monday. 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 02/0300Z 16.6N 59.1W 45 KT 50 MPH 12H 02/1200Z 17.0N 59.8W 45 KT 50 MPH 24H 03/0000Z 17.8N 60.7W 45 KT 50 MPH 36H 03/1200Z 19.0N 61.3W 50 KT 60 MPH 48H 04/0000Z 20.3N 61.7W 50 KT 60 MPH 60H 04/1200Z 22.0N 61.8W 50 KT 60 MPH 72H 05/0000Z 23.8N 61.7W 55 KT 65 MPH 96H 06/0000Z 27.5N 60.2W 65 KT 75 MPH 120H 07/0000Z 30.1N 57.6W 75 KT 85 MPH $$ Forecaster Pasch |
