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| #1155033 (Received by flhurricane at: 4:56 AM 29.Sep.2023) TCDAT2 Tropical Storm Philippe Discussion Number 24 NWS National Hurricane Center Miami FL AL172023 500 AM AST Fri Sep 29 2023 A 0546 UTC GMI microwave pass showed that Philippe continues to have a broad circulation, with the low-level center located somewhere near the northwestern edge of a large area of deep convection. There is a large range in the subjective Dvorak estimates (30-55 kt), but the various objective numbers from UW-CIMSS are in closer agreement (35-45 kt). Using a blend of these values, as well as ASCAT data from last evening, Philippe`s intensity is held at 40 kt. While there is a bit of uncertainty in the exact location of the center, the storm does appear to be drifting toward the southwest (235 degrees) at about 2 kt. Philippe`s movement during the next 3-4 days is likely to be dictated by binary interaction with Tropical Storm Rina to the east. The bulk of the track guidance indicates that Philippe will dip farther toward the southwest during the next 48 hours due to Rina`s influence, but then turn toward the northwest and north on days 3 through 5 as a mid-tropospheric high builds over the central Atlantic. The new NHC track forecast is not much different from the previous prediction and is close to the TVCA and HCCA consensus aids. The HAFS regional hurricane models show little to no interaction between Philippe and Rina during the next few days. However, with the two storms located only 500 n mi apart from each other, some degree of interaction is likely, and therefore the western solutions shown by those models (near or over the northern Leeward Islands) appear to be outliers at this time. That said, there continues to be larger-than-normal uncertainty in Philippe`s future track. A combination of shear, dry air, and Philippe`s proximity to Rina are likely to cause little change in intensity for the next day or so. However, the global models have trended toward Philippe not only surviving the next few days, but also deepening in an environment of increasing upper-level divergence (and still over very warm waters of 29-30 degrees Celsius). The NHC intensity forecast has been nudged upward from 36 hours onward, although it still sits well below most of the intensity models, including the consensus aids, during the latter part of the forecast period. Until it becomes more clear how Philippe will evolve over the next couple of days, the official intensity forecast will remain on the conservative side, but future adjustments to the forecast are becoming more likely. FORECAST POSITIONS AND MAX WINDS INIT 29/0900Z 18.5N 55.2W 40 KT 45 MPH 12H 29/1800Z 18.3N 55.4W 40 KT 45 MPH 24H 30/0600Z 17.9N 55.7W 40 KT 45 MPH 36H 30/1800Z 17.4N 56.0W 45 KT 50 MPH 48H 01/0600Z 17.1N 56.4W 50 KT 60 MPH 60H 01/1800Z 17.1N 56.8W 50 KT 60 MPH 72H 02/0600Z 17.6N 57.2W 55 KT 65 MPH 96H 03/0600Z 20.0N 57.9W 55 KT 65 MPH 120H 04/0600Z 23.1N 58.1W 55 KT 65 MPH $$ Forecaster Berg |
