Issued at 500 AM AST Mon Sep 22 2025
000 WTNT42 KNHC 220858 TCDAT2 Hurricane Gabrielle Discussion Number 21 NWS National Hurricane Center Miami FL AL072025 500 AM AST Mon Sep 22 2025 Satellite images show that deep convection wraps around the inner core of Gabrielle with cold cloud tops near -80C, and GLM data depicts some lightning ongoing near the center of the system. Unfortunately, there have been no microwave images this morning to get a better idea of the hurricanes structure. However, there have been brief hints that an eye may be trying to form in infrared imagery. There is a fairly large range of subjective and objective satellite intensity estimates. Latest Dvorak satellite intensity estimates from TAFB and SAB range from 77 kt to 90 kt, and estimates from UW-CIMSS such as DPRINT, AiDT, and SATCON range from 57 to 79 kt. Using these estimates and the improved satellite presentation, the intensity is raised to 80 kt for this advisory. Gabrielle is moving north-northwestward at an estimated motion of 340/9 kt. A turn towards the north is expected today and tonight as Gabrielle rounds the western periphery of a subtropical ridge. The system will then be steered within stronger west-southwesterly mid-latitude flow, and accelerate towards the northeast and east-northeast during the next few days. The latest track guidance is in fairly good agreement in the short term, and the NHC forecast was nudged slightly westward in the short-term, given the initial position, but lies near the previous. However, beyond days 2-3 there continues to be a large spread in the track guidance suite and mainly due to differences in the forward speed of Gabrielle. The latest NHC forecast is a little faster than the previous forecast and lies closer to the HCCA corrected consensus, but is not as fast as the Google DeepMind. Given uncertainty in the track forecast at long ranges, it is too early to predict what, if any, impacts Gabrielle could have on the Azores. The hurricane is within a favorable environment for strengthening, over the next 24 hours or so, with warm sea surface temperatures and light to moderate wind shear. The NHC intensity forecast lies near the higher end of the guidance envelope near the hurricane regional models, with Gabrielle forecast to become a major hurricane tonight. After that time, moderate to strong westerly wind shear will begin to impact the system, as well as slightly drier mid-level air. By day 3, sea surface temperatures drop to around 26 C, and will continue to cool along the forecast track. Thus a weakening trend is forecast beyond 24h and the NHC forecast trends towards the consensus aids through the middle and end of the forecast period. Global models and SHIPS guidance are in slightly better agreement that Gabrielle will begin to transition to an extratropical cyclone towards the end of the period and the latest NHC forecast now shows the system Extra-Tropical by day 5. It should be noted that some models do show Gabrielle attaining extratropical characteristics sooner than explicitly forecast. KEY MESSAGES: 1. Gusty winds and showers will be possible across Bermuda today and tonight as Hurricane Gabrielle passes by to the east. 2. Swells generated by Gabrielle will continue to affect Bermuda during the next few days. These swells are now reaching the east coast of the United States from North Carolina northward, as well as Atlantic Canada, and should continue during the next couple of days. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. FORECAST POSITIONS AND MAX WINDS INIT 22/0900Z 30.0N 62.5W 80 KT 90 MPH 12H 22/1800Z 31.3N 62.1W 95 KT 110 MPH 24H 23/0600Z 32.9N 60.5W 105 KT 120 MPH 36H 23/1800Z 34.4N 57.4W 95 KT 110 MPH 48H 24/0600Z 35.4N 53.1W 90 KT 105 MPH 60H 24/1800Z 36.0N 47.6W 80 KT 90 MPH 72H 25/0600Z 36.7N 41.5W 75 KT 85 MPH 96H 26/0600Z 40.7N 28.9W 70 KT 80 MPH 120H 27/0600Z 44.2N 19.9W 55 KT 65 MPH...POST-TROP/EXTRATROP $$ Forecaster Kelly
NHC Atlantic
