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| #1154995 (Received by flhurricane at: 10:50 PM 28.Sep.2023) TCDAT2 Tropical Storm Philippe Discussion Number 23 NWS National Hurricane Center Miami FL AL172023 1100 PM AST Thu Sep 28 2023 There has not been much change in Philippe`s organization this evening with deep convection pulsing around the eastern and southern portions of the circulation. Satellite imagery and a very recently arriving ASCAT pass indicate that the circulation is quite elongated east to west. In fact, the ASCAT data suggests Philippe likely lacks a well-defined center, but there are some indications that a center may be trying to re-form farther east. Subjective Dvorak T-numbers from SAB and TAFB were T2.0 (30 kt) and T2.5 (35 kt), respectively at 00Z, but the recently arriving ASCAT data revealed winds of around 35-36 kt. Given the typical undersampling of that instrument, the initial wind speed is held at 40 kt. The scatterometer data suggests that Philippe is located a little south of the previous estimates, but the storm appears to have moved little since the previous advisory. The track forecast is still quite challenging due to the current disorganized structure and the close proximity of Tropical Storm Rina to Philippe`s east. The dynamical model guidance suggests that the cyclone will move slowly southwestward as Rina moves to the northeast of Philippe during the next two to three days. By early next week, the storm is forecast to begin moving northward between a mid-level ridge over the east-central Atlantic and a mid- to upper-level trough over the southwestern Atlantic. There is still significant spread in the models on where Philippe makes the northward turn, but the guidance is in slightly better agreement than 24 hours ago. The updated NHC track is a little to the right of the previous forecast, but it lies a little west of the latest consensus aids. There continues to be larger-than-normal uncertainty in the latter portion of the track forecast. Westerly shear, dry air, and Philippe`s close proximity to Rina have continued to prevent any increase in organization today. Those negative environmental factors are expected to linger during the next day or so, and little overall change in strength is forecast during that time. Although not explicitly shown in this forecast or by most of the model guidance, it is possible that Philippe`s circulation becomes increasing elongated and the system dissipates within the next couple of days. However, most of the guidance shows Philippe surviving, and then finding a more favorable environment in which to strengthen early next week. The NHC intensity forecast has been nudged upward from 72-120 h, but it remains below much the latest dynamical guidance and the consensus aids. Until there is a bit more clarity it seems prudent to stay on the more conservative side of the guidance. As with the track forecast, there is still significant uncertainty in the long-range intensity prediction for Philippe. FORECAST POSITIONS AND MAX WINDS INIT 29/0300Z 18.3N 55.0W 40 KT 45 MPH 12H 29/1200Z 18.2N 55.2W 40 KT 45 MPH 24H 30/0000Z 17.9N 55.6W 40 KT 45 MPH 36H 30/1200Z 17.6N 55.9W 40 KT 45 MPH 48H 01/0000Z 17.2N 56.2W 45 KT 50 MPH 60H 01/1200Z 17.0N 56.6W 45 KT 50 MPH 72H 02/0000Z 17.0N 57.0W 50 KT 60 MPH 96H 03/0000Z 18.8N 57.6W 50 KT 60 MPH 120H 04/0000Z 21.7N 58.3W 50 KT 60 MPH $$ Forecaster Brown |
