Hurricane Henriette Forecast Discussion Number 30
Issued at 500 AM HST Mon Aug 11 2025
136 WTPA43 PHFO 111445 TCDCP3 Hurricane Henriette Discussion Number 30 NWS Central Pacific Hurricane Center Honolulu HI EP082025 Issued by NWS National Hurricane Center Miami FL 500 AM HST Mon Aug 11 2025 Henriette has been going through some rapid structural changes during the past several hours. A 1138 UTC GMI microwave pass confirmed that an eyewall replacement was in the process of occurring, with a ring of deep convection surrounding a small remnant of the previous eyewall. Since that time, convection appears to have redeveloped in the inner eyewall, and a small eye is trying to form in conventional satellite imagery. Dvorak CI numbers at 1200 UTC from PHFO, SAB, and JTWC ranged between 4.0/65 kt and 4.5/77 kt, while most of the objective numbers are between 70-80 kt. The initial intensity is raised to 75 kt as a blend of all these numbers. The hurricane is moving quickly toward the northwest, or 310/16 kt. The forecast track is remarkably straight and steady during the next 48 hours or so, as Henriette is steered between a mid-level low northwest of the Hawaiian Islands and a large ridge centered off the coast of the Pacific Northwest United States. After 48 hours, the cyclone is expected to turn toward the north-northwest and slow down when it reaches the western periphery of the ridge. Confidence remains high in the track forecast, and the new NHC prediction is right on top of the previous one, lying close to the TVCE and HCCA consensus aids. Henriette probably has another 12-24 hours to take advantage of an environment of sufficiently warm sea surface temperatures, low shear, and upper-level divergence. The NHC forecast therefore shows a little more strengthening in the short term. Although ocean temperatures only become gradually cooler after that time, the atmosphere quickly becomes less conducive with an increase in shear and convergence aloft. Weakening is therefore indicated, at a rate similar to the bulk of the guidance, and Henriette could become post-tropical in about 60 hours when it loses its organized deep convection. The post-tropical cyclone/remnant low is then likely to dissipate by day 5 over the far northern Pacific. FORECAST POSITIONS AND MAX WINDS INIT 11/1500Z 28.8N 156.5W 75 KT 85 MPH 12H 12/0000Z 30.4N 158.6W 80 KT 90 MPH 24H 12/1200Z 32.5N 161.1W 75 KT 85 MPH 36H 13/0000Z 34.5N 163.7W 70 KT 80 MPH 48H 13/1200Z 36.5N 166.4W 50 KT 60 MPH 60H 14/0000Z 38.5N 168.6W 40 KT 45 MPH...POST-TROPICAL 72H 14/1200Z 40.4N 169.9W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 15/1200Z 43.1N 171.1W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 16/1200Z...DISSIPATED $$ Forecaster Berg
