Issued at 1100 PM AST Tue Sep 30 2025
080 WTNT43 KNHC 010245 TCDAT3 Hurricane Humberto Discussion Number 26 NWS National Hurricane Center Miami FL AL082025 1100 PM AST Tue Sep 30 2025 Humberto continues to produce a very large area of deep convection, primarily to the northeast of its circulation center. However, a 2106 UTC GPM microwave pass received after the prior advisory still showed the low-level center was mostly exposed on the southwest edge of the cirrus canopy. Satellite estimates have only been in the 45-55 kt range for the last 6-12 hours. However, a recently received ASCAT pass showed a peak wind retrieval of 61 kt, and assuming the significant low bias of this instrument at hurricane intensity, the initial intensity is being held at 70 kt for this advisory. Wind radii were also adjusted based on the scatterometer data. The hurricane appears to have made an east-northeastward turn, but has not accelerated, with the motion estimated at 065/9 kt. A longwave mid-latitude trough located to the north of Humberto is quickly dropping southward and will soon start to impinge upon the hurricane's circulation. The resulting interaction should cause a strengthening frontal boundary to form to the northeast of Humberto's center. In fact, the scatterometer data already shows this boundary beginning to develop in the convection. The global and hurricane-regional model fields now show Humberto's circulation quickly becoming indistinguishable from the intensifying baroclinic zone in 18-24 h. The latest NHC track and intensity forecast will now show Humberto merging with this boundary by that time. The remnant vorticity of the storm may ultimately be advected towards Imelda's circulation beyond that time frame, as it also interacts with the same boundary. Regardless of Humberto's evolution, the hurricane, in combination with Imelda is producing a large area of hazardous marine conditions over the western and central Atlantic, where life-threatening rip currents are expected to affect beaches throughout the region through the week. KEY MESSAGES: 1. Dangerous marine conditions, including high surf and life-threatening rip currents, will continue to affect beaches of the northern Caribbean, Bahamas, Bermuda, and much of the east coast of the United States through the week. FORECAST POSITIONS AND MAX WINDS INIT 01/0300Z 34.8N 68.5W 70 KT 80 MPH 12H 01/1200Z 35.3N 67.4W 65 KT 75 MPH 24H 02/0000Z...MERGED WITH A FRONTAL BOUNDARY $$ Forecaster Papin
