Issued at 800 AM MST Fri May 30 2025
000 WTPZ41 KNHC 301435 TCDEP1 Tropical Storm Alvin Discussion Number 8 NWS National Hurricane Center Miami FL EP012025 800 AM MST Fri May 30 2025 Alvin is now moving into an area of stronger south to southwesterly wind shear, and water vapor imagery shows the cyclone moving into a progressively drier airmass. The center is estimated to be underneath the southern portion of the convection. The convective organization of the cyclone appears to have degraded slightly over the past 6 hours. Recent AMSR2 and GMI microwave passes show that the convection in the southern semicircle has completely eroded. CI numbers from TAFB and SAB both remain at T-3.0/45 kt, and objective intensity estimates from UW-CIMSS are a bit higher. Given the large area of 40-45 kt winds on the ASCAT pass from 0438 UTC this morning, 45 kt is held for this advisory. The initial motion is estimated to be northwest, or 325/9-kt. Alvin is forecast to turn northward over the next day or so as it moves through a weakness in the subtropical ridge, toward the east side of a mid-level cutoff low located just west of Baja California. Little change is made to the previous NHC track prediction, which lies down the middle of the consensus model envelope. Alvin will continue moving into an increasingly hostile environment of very strong wind shear, dry air, and sea-surface temperatures that will drop below 26C along Alvin's path in about 12 hours. These conditions will lead to Alvin losing its convection by Saturday, which is depicted by the GFS and ECMWF simulated satellite imagery. There are no significant changes to the NHC intensity forecast, and Alvin is forecast to degenerate to a remnant low in about 24 hours, with dissipation in a little over 2 days. FORECAST POSITIONS AND MAX WINDS INIT 30/1500Z 17.4N 108.8W 45 KT 50 MPH 12H 31/0000Z 18.7N 109.1W 35 KT 40 MPH 24H 31/1200Z 20.3N 109.4W 30 KT 35 MPH...POST-TROP/REMNT LOW 36H 01/0000Z 21.8N 109.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 01/1200Z 23.5N 109.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 60H 02/0000Z...DISSIPATED $$ Forecaster Hagen
