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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
 
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