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| #1154359 (Received by flhurricane at: 4:56 PM 24.Sep.2023) TCDAT2 Tropical Storm Philippe Discussion Number 6 NWS National Hurricane Center Miami FL AL172023 500 PM AST Sun Sep 24 2023 Microwave and satellite data indicate that the center of Philippe has re-formed to the northeast of earlier estimates. Overall, the storm is reasonably well organized, with convection near the center and a large central dense overcast. Intensity estimates are about the same as the last cycle, so the initial wind speed remains 45 kt. There aren`t many changes to the intensity prediction reasoning in this advisory. Increasing shear is forecast to otherwise counteract a conducive environment, leading to little net change with Philippe during the next couple of days. Afterwards, models are in quite poor agreement on if the shear continues to rise to strong levels, which causes dissipation like the ECMWF, or if it becomes more manageable to allow for further intensification, similar to the GFS`s hurricane forecast at day 5. There are no obvious clues to the correct solution, and this is probably a very difficult forecast due to the feedback of Philippe`s track affecting intensity, in addition to the inherent challenges of moderate shear cases. Thus, little change was made to the intensity forecast, which lies near the overall model and corrected-consensus aids. The storm appears to be moving west-northwestward or 290/10 kt. The subtropical ridge to the north of Philippe is forecast to gradually weaken and slide eastward in a day or two, allowing the tropical storm to move more west-northwestward and northwestward by the middle of the week. Uncertainty is large after that point, with the track very likely also dependent on the intensity and vortex depth, and the GFS and ECMWF models are on the opposite sides of the guidance envelope. The long-range guidance has shifted a bit westward on this cycle, and the new forecast follows that trend. However, this forecast should be considered low-confidence in both track and intensity. FORECAST POSITIONS AND MAX WINDS INIT 24/2100Z 16.8N 42.5W 45 KT 50 MPH 12H 25/0600Z 17.3N 44.1W 45 KT 50 MPH 24H 25/1800Z 17.8N 46.4W 45 KT 50 MPH 36H 26/0600Z 18.2N 48.6W 45 KT 50 MPH 48H 26/1800Z 18.8N 50.4W 45 KT 50 MPH 60H 27/0600Z 19.7N 52.0W 50 KT 60 MPH 72H 27/1800Z 21.0N 53.5W 50 KT 60 MPH 96H 28/1800Z 23.0N 55.5W 55 KT 65 MPH 120H 29/1800Z 25.0N 57.0W 60 KT 70 MPH $$ Forecaster Blake |
