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| #1155153 (Received by flhurricane at: 10:46 PM 29.Sep.2023) TCDAT2 Tropical Storm Philippe Discussion Number 27 NWS National Hurricane Center Miami FL AL172023 1100 PM AST Fri Sep 29 2023 Deep convection continues to pulse over the southeastern portion of Philippe`s circulation this evening. The center is located near the northwestern edge of the deep convection due to moderate westerly shear. The intensity is held at 45 kt, and is based on the earlier reconnaissance aircraft data and a T3.0 (45 kt) subjective Dvorak classification from TAFB. Another Air Force Reserve reconnaissance mission is scheduled overnight, and this mission should provide a full assessment of Philippe`s structure and intensity. The earlier aircraft center fixes and more recent satellite position estimates indicate that Philippe is moving slowly southwestward. This motion is being influenced by Philippe`s interaction with Tropical Storm Rina located to Philippe`s east-northeast. As the two tropical cyclone`s continue to interact, Philippe is expected to move slowly west-southwestward to westward during the next 24 to 36 hours. After that time, the distance between the tropical cyclones should increase, and Philippe is forecast to turn northwestward when a mid-level ridge builds over the central Atlantic. After 72 hours, Philippe is expected to turn northward between the aforementioned ridge and a mid- to upper-level trough over the southwestern Atlantic. Although the models are in general agreement on this scenario, there is significant spread on the longitude of the northward turn, and on how fast Philippe moves later in the period. The updated NHC track forecast is near the various consensus aids, and very close to the previous advisory. The moderate shear that has been affecting Philippe the past few days could lessen during the next day or two. This should allow for some gradual strengthening over the weekend. After that time, there is a bifurcation in the intensity guidance with the GFS-based SHIPS model, the HMON, the HWRF, and even the GFS showing a more favorable upper-air environment and more significant deepening with a track farther east. Meanwhile, the ECMWF-based SHIPS guidance, and the HAFS-A and HAFS-B which show a more westward track keeps stronger southwesterly vertical wind shear over the storm and therefore less strengthening. The NHC intensity foreast is near the middle of these two scenarios, but is a bit more conservative than the lastest intensity consensus models. FORECAST POSITIONS AND MAX WINDS INIT 30/0300Z 17.6N 55.8W 45 KT 50 MPH 12H 30/1200Z 17.3N 56.0W 45 KT 50 MPH 24H 01/0000Z 17.2N 56.4W 50 KT 60 MPH 36H 01/1200Z 17.3N 56.9W 55 KT 65 MPH 48H 02/0000Z 17.8N 57.5W 60 KT 70 MPH 60H 02/1200Z 18.7N 58.2W 60 KT 70 MPH 72H 03/0000Z 20.2N 58.7W 60 KT 70 MPH 96H 04/0000Z 23.4N 58.9W 60 KT 70 MPH 120H 05/0000Z 27.3N 57.5W 60 KT 70 MPH $$ Forecaster Brown |
