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| #1154798 (Received by flhurricane at: 4:40 PM 27.Sep.2023) TCDAT2 Tropical Storm Philippe Discussion Number 18 NWS National Hurricane Center Miami FL AL172023 500 PM AST Wed Sep 27 2023 Philippe`s convection continues to oscillate this afternoon. Shortly after the previous advisory, the convection waned and has become less organized. An ASCAT-C pass showed that the center of the system has become more ill-defined, with the low-level center difficult to pinpoint this afternoon. Convection continues to redevelop back to the east, with the expected mean center on the west side of the convection. This was further supported by an AMSR microwave overpass depicting and overall lack of organization. Subjective Dvorak data-T numbers have come down with the current intensity estimates remaining at 3.0. Given the earlier ASCAT-B pass and the CI intensity estimates, the initial intensity will is held at 45 kt, but this could be generous. This is a fairly complicated intensity and track forecast. Philippe is in a sheared environment, and currently lacks organization. The system is forecast to move into a slightly drier mid-level airmass in a few days, which may also inhibit the overall convective pattern. Some slight fluctuations in intensity may occur due to the pulsing convective nature of the system during the next few days, with an overall slow weakening trend later this weekend. There remains uncertainty in the intensity forecast and it is possible Philippe maintains its tropical cyclone status as it reaches the northern Leeward Islands, or the system could weaken and open into a trough. The estimated motion is west-northwestward at 4 kt. Philippe is currently being steered by the flow around a weak mid-level ridge and is expected to move west-northwestward over the next couple of days. In the latter part of the forecast period, a weakening and shallow system should turn toward the west-southwest. There is unusually large spread in the model guidance this cycle with the GFS and ECMWF over 1100 miles apart on Day 5. The GFS is stronger and on the right side, of the guidance envelope which has pulled the consensus aids right as well. The ECMWF is weaker and on the left side of the guidance. The track forecast is highly dependent on the intensity forecast, however. The official track forecast is similar to the previous forecast, just slower given the initial slower motion, which is closest to the ECMWF. FORECAST POSITIONS AND MAX WINDS INIT 27/2100Z 17.7N 54.0W 45 KT 50 MPH 12H 28/0600Z 18.1N 55.1W 45 KT 50 MPH 24H 28/1800Z 18.6N 56.5W 40 KT 45 MPH 36H 29/0600Z 18.9N 57.7W 40 KT 45 MPH 48H 29/1800Z 18.9N 58.8W 40 KT 45 MPH 60H 30/0600Z 18.8N 60.0W 35 KT 40 MPH 72H 30/1800Z 18.7N 61.6W 35 KT 40 MPH 96H 01/1800Z 18.4N 64.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 02/1800Z 18.2N 66.3W 30 KT 35 MPH...POST-TROP/REMNT LOW $$ Forecaster Kelly |
