Issued at 500 AM AST Sat Sep 20 2025
000 WTNT42 KNHC 200837 TCDAT2 Tropical Storm Gabrielle Discussion Number 13 NWS National Hurricane Center Miami FL AL072025 500 AM AST Sat Sep 20 2025 Although Gabrielle's low-level center is obscured by high cirrus clouds, an 0555 UTC AMSR2 microwave pass confirms that it is still located to the west of the deep convective mass due to continued moderate westerly shear. The convection itself has been quite intense, with a high density of lightning co-located with cloud-top temperatures as cold as -85 to -90 degrees Celsius. The latest satellite intensity estimates, as well as ASCAT data from yesterday evening, still support an intensity of 45 kt. The ASCAT data also showed that there are currently no tropical-storm-force winds on Gabrielle's western side. Mid-tropospheric high pressure over the central Atlantic is steering Gabrielle northwestward, or 315 degrees at 11 kt. The storm is expected to recurve between the western periphery of the high and a trough located over the southeastern United States over the next several days. Mostly because of an adjustment of Gabrielle's initial position, the new NHC track forecast has been adjusted a bit west of the previous prediction during the first 3 days of the forecast. That said, all of the reliable track models continue to keep the core of Gabrielle well east of Bermuda Sunday night and Monday during the recurvature. By Tuesday, global model fields indicate that Gabrielle will become embedded in fast zonal mid-latitude flow, and there has been a significant southward shift in the track models on days 4 and 5. The NHC track forecast has also been adjusted southward at those times, close to the HCCA and Google DeepMind ensemble but not as far south as the GFS and many of the multi-model consensus aids. Vertical shear is expected to decrease over the next day or two, which should allow Gabrielle's circulation to become more vertically aligned, leading to strengthening. The intensity models are generally split into two camps. The statistical-dynamical models (SHIPS and LGEM) and global models (GFS and ECMWF) are more subdued on the amount of strengthening that Gabrielle might experience. The regional hurricane models, as well as the HCCA and Florida State Superensemble, are more aggressive, with the HAFS models in particular bringing Gabrielle to major hurricane strength in about 2 days. While not going that high, the NHC intensity forecast is close to the other models in that camp and continues to show a possible peak of 90 kt in 60-72 hours. With the southward shift in the track forecast at days 4 and 5, Gabrielle's extratropical transition has likely been delayed, and the official forecast continues to depict a tropical cyclone through the next 5 days. KEY MESSAGES: 1. Gabrielle is forecast to become a hurricane by Sunday and pass east of Bermuda Sunday night and Monday. Interests on Bermuda should continue to monitor Gabrielle's forecasts since some wind and rainfall impacts are still possible. 2. Swells generated by Gabrielle are beginning to reach Bermuda and will build through the weekend. These swells are likely to cause life-threatening surf and rip current conditions. FORECAST POSITIONS AND MAX WINDS INIT 20/0900Z 24.3N 58.1W 45 KT 50 MPH 12H 20/1800Z 25.4N 59.3W 50 KT 60 MPH 24H 21/0600Z 27.0N 60.5W 60 KT 70 MPH 36H 21/1800Z 28.6N 61.6W 70 KT 80 MPH 48H 22/0600Z 30.3N 62.1W 80 KT 90 MPH 60H 22/1800Z 32.1N 61.3W 90 KT 105 MPH 72H 23/0600Z 34.0N 59.1W 90 KT 105 MPH 96H 24/0600Z 37.0N 50.6W 80 KT 90 MPH 120H 25/0600Z 38.7N 38.5W 65 KT 75 MPH $$ Forecaster Berg
NHC Atlantic
