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| #1246561 (Received by flhurricane at: 5:00 PM 29.Sep.2025) TCDAT3 Hurricane Humberto Discussion Number 21 NWS National Hurricane Center Miami FL AL082025 500 PM AST Mon Sep 29 2025 After some brief re-intensification this morning, satellite imagery depicts that Humberto has started to feel the impacts of wind shear. The ring of deep convection has become a little more broken on infrared imagery, particularly on the western side of the system. Earlier Hurricane Hunter aircraft data depicted that the eyewall was open on the southwest side, and recent microwave imagery shows that the eyewall may be completely open on the western side. As the previous aircraft was departing, the pressure had come up a couple millibars which also suggests the system may have begun to weaken, and thus that trend is followed in this advisory. Using the latest satellite trends, and a combination of intensity estimates with previous aircraft data, the intensity is lowered to 120 kt for this advisory. Another Air Force Reserve Hurricane Hunter aircraft is scheduled to investigate the system late this evening to help evaluate the intensity and structure of the system. Humberto is moving north-northwestward at an estimated motion of 330/11 kt. The system should continue to round the western periphery of the mid-level ridge and gradually turn to the north then northeast over the next day or so. A trough moving into the northern Atlantic will then pick up the system, and cause Humberto to accelerate to the northeast to east-northeast over the next several days. There is slightly more along-track spread with the forward speed towards the end of the forecast period in the latest guidance envelope. The NHC track forecast is near the previous one, however slightly slower at long range, and lies near the consensus track aids. A weakening trend has started with Humberto, as wind shear appears to have started to disrupt the circulation. Wind shear is forecast to continue increasing over the system, and sea surface temperatures will also cool along the forecast track. Model simulated IR images depicts that Humberto will become more asymmetric with most of the convection displaced to the eastern side of the circulation due to the shear. In about 60 h, both the GFS and ECMWF guidance depict that the system should merge with the previously mentioned trough digging across the north Atlantic and develop frontal features. As the system becomes extratropical across the north Atlantic, the wind field is anticipated to grow in size. The latest NHC intensity forecast lies on the higher end of the guidance envelope given the latest increase in intensity, and then shows weakening throughout the period. By 96h, the system is expected to dissipate and merge within the larger trough. Along the forecast track, Humberto is expected to move to the west and north of Bermuda, gusty winds and heavy rainfall are possible within outer rainbands late Tuesday and Wednesday. KEY MESSAGES: 1. Gusty winds and heavy rainfall are possible within outer rainbands of Humberto. The Tropical Storm Watch has been replaced with a Hurricane Watch, due to the forecast of Imelda. Please follow local updates from Bermuda Weather Service for impacts from Humberto. 2. Dangerous marine conditions, including high surf and life-threatening rip currents, are affecting beaches of the northern Caribbean, Bahamas, Bermuda, and much of the east coast of the United States. FORECAST POSITIONS AND MAX WINDS INIT 29/2100Z 29.1N 68.1W 120 KT 140 MPH 12H 30/0600Z 30.8N 68.8W 105 KT 120 MPH 24H 30/1800Z 33.4N 68.6W 90 KT 105 MPH 36H 01/0600Z 35.4N 66.4W 85 KT 100 MPH 48H 01/1800Z 36.8N 61.8W 75 KT 85 MPH 60H 02/0600Z 38.4N 54.9W 65 KT 75 MPH...POST-TROP/EXTRATROP 72H 02/1800Z 41.5N 46.0W 60 KT 70 MPH...POST-TROP/EXTRATROP 96H 03/1800Z...DISSIPATED $$ Forecaster Kelly |
