Issued at 500 AM AST Fri Sep 19 2025
859 WTNT42 KNHC 190846 TCDAT2 Tropical Storm Gabrielle Discussion Number 9 NWS National Hurricane Center Miami FL AL072025 500 AM AST Fri Sep 19 2025 Gabrielle's low-level center is located near the western edge of an area of deep convection that has now persisted since late yesterday afternoon. While the overall convective structure is gradually improving, the change hasn't been enough to deviate from a current intensity of 45 kt. UW-CIMSS SATCON, with a value of 42 kt, is currently the closest satellite intensity estimate. The storm is maintaining a west-northwestward heading of 300 degrees at 10 kt, with the subtropical ridge located to its north. A general pattern of troughing is expected to persist near the southeastern U.S. coast and far western Atlantic for the next several days, which should cause Gabrielle to recurve around the western periphery of the ridge over the next 4 days. There has been further tightening of the track guidance during this period, including a convergence of the HCCA and Google DeepMind ensemble mean, and no significant adjustments were required for this updated track forecast. The reliable track models now show Gabrielle's center passing at least 140 n mi east of Bermuda in about 3 days. However, interests on the island should continue to monitor Gabrielle's progress since NHC's average track error at 3 days is about 90 n mi, and hazards can extend well away from the center. There is currently a 20-25 percent chance of tropical-storm-force winds occurring on Bermuda. The moderate westerly shear currently affecting Gabrielle is forecast to gradually lessen below 10 kt by 36 hours. This should begin to mitigate the effects of surrounding dry air and allow for gradual strengthening. The NHC intensity forecast has been nudged upward, particularly during the first 3 days, to trend toward the latest IVCN and HCCA consensus aids, and Gabrielle is expected to become a hurricane by Sunday. The forecast peak intensity on day 4 is unchanged. By day 5, the onset of significantly stronger shear and cooler waters should induce some weakening. At the moment, there is significant uncertainty about when Gabrielle might become extratropical and how that would affect the cyclone's intensity. 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 monitor Gabrielle's forecasts since it is too soon to specify the magnitude of potential wind and rainfall impacts. 2. Swells generated by Gabrielle are expected to reach Bermuda tonight and build through the weekend. These swells are likely to cause life-threatening surf and rip current conditions. FORECAST POSITIONS AND MAX WINDS INIT 19/0900Z 21.9N 54.8W 45 KT 50 MPH 12H 19/1800Z 22.6N 56.0W 45 KT 50 MPH 24H 20/0600Z 23.9N 57.7W 50 KT 60 MPH 36H 20/1800Z 25.4N 59.2W 55 KT 65 MPH 48H 21/0600Z 27.1N 60.3W 60 KT 70 MPH 60H 21/1800Z 28.9N 61.2W 70 KT 80 MPH 72H 22/0600Z 31.0N 61.2W 80 KT 90 MPH 96H 23/0600Z 35.9N 56.9W 90 KT 105 MPH 120H 24/0600Z 39.8N 46.0W 75 KT 85 MPH $$ Forecaster Berg
NHC Atlantic
