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| #1154494 (Received by flhurricane at: 4:53 PM 25.Sep.2023) TCDAT2 Tropical Storm Philippe Discussion Number 10 NWS National Hurricane Center Miami FL AL172023 500 PM AST Mon Sep 25 2023 Visible satellite images continue to show Philippe with a fully exposed center far removed to the west of all of the deep convection. The continued disorganized appearance suggests at least some weakening has occurred, and satellite intensity estimates concur. Thus, the wind speed has been lowered to 40 kt. Philippe continues to be impacted by 20-25 kt of deep-layer west-southwesterly vertical wind shear. This wind shear is forecast by both GFS- and ECMWF-based SHIPS models to persist or even increase further during the next few days. This unfavorable shear combined with dry air entrainment will hinder strengthening through the forecast period. A few models suggest some slight increase in intensity in the 48- to 72-hour time frame due to warmer sea-surface temperatures, but other environmental factors will remain negative. The new forecast indicates no change in strength over the next several days, with some weakening toward the end of the forecast period. The exposed low-level center of Philippe has been moving west today with a slight increase in forward motion this afternoon. The system should veer toward the west-northwest tonight then turn northwest by mid-week as Philippe moves toward a weakness in the subtropical ridge. By late week, this weakness becomes less pronounced and the overall steering flow diminishes. The forecast track at the end of the period therefore slows and curves back toward the west-northwest. There remains considerable spread in the track models this afternoon, with the GFS and its ensemble members representing far rightward outliers. With the ongoing motion to the west and a leftward shift of the overall guidance output, the NHC forecast track has been adjusted slightly west, especially beyond 72 hours due to the aforementioned steering flow changes. FORECAST POSITIONS AND MAX WINDS INIT 25/2100Z 17.3N 46.7W 40 KT 45 MPH 12H 26/0600Z 17.7N 48.5W 40 KT 45 MPH 24H 26/1800Z 18.4N 50.4W 40 KT 45 MPH 36H 27/0600Z 19.3N 52.3W 40 KT 45 MPH 48H 27/1800Z 20.4N 54.0W 40 KT 45 MPH 60H 28/0600Z 21.6N 55.4W 40 KT 45 MPH 72H 28/1800Z 22.2N 56.3W 40 KT 45 MPH 96H 29/1800Z 22.9N 57.7W 40 KT 45 MPH 120H 30/1800Z 23.4N 59.5W 35 KT 40 MPH $$ Forecaster Konarik/Cangialosi |
