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Tropical Storm Henriette Discussion Number   4
NWS National Hurricane Center Miami FL       EP082025
500 PM HST Mon Aug 04 2025
 
Henriette has become slightly better organized this afternoon, with 
curved banding becoming more defined and a brief burst of deep 
convection developing over the low-level center.  The latest 
subjective Dvorak intensity estimates from TAFB and SAB are both 
3.0/45 knots, while objective estimates from UW-CIMSS have ranged 
from 39 to 43 knots during the past few hours and show an upward 
trend.  Based on these data, the initial intensity for this advisory 
has been increased to 45 knots.

The cyclone is moving west-northwest, or 290 degrees, at 13 knots.  
This general motion is expected to continue during the next couple 
of days as Henriette moves along the southern edge of a subtropical 
ridge to the north.  Between 48 and 72 hours, a slight turn toward 
the west is forecast as the ridge strengthens north of the cyclone.  
Beyond 72 hours, a turn back toward the west-northwest or northwest 
is anticipated as a weakness develops in the ridge north of Hawaii 
due to an amplifying longwave trough near 160W. The official track 
forecast remains near the center of the tightly clustered guidance 
envelope and is very close to the previous advisory.

Henriette appears to have a brief window for further intensification 
over the next day or so, as sea surface temperatures hover between 
26 and 27C, mid-level moisture remains sufficient, and vertical wind 
shear stays light.  After 36 hours, the cyclone is expected to move 
over progressively cooler waters, with mid-level moisture gradually 
decreasing, and these conditions should lead to steady weakening. 
The official forecast maintains Henriette as a tropical cyclone 
through 120 hours, however, it would not be surprising if it 
transitions into a post-tropical low prior to day 5. The intensity 
forecast is most closely aligned with the SHIPS and ICON guidance.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  05/0300Z 15.4N 121.9W   45 KT  50 MPH
 12H  05/1200Z 16.0N 123.7W   50 KT  60 MPH
 24H  06/0000Z 16.9N 126.4W   55 KT  65 MPH
 36H  06/1200Z 17.5N 129.2W   55 KT  65 MPH
 48H  07/0000Z 18.0N 132.0W   50 KT  60 MPH
 60H  07/1200Z 18.3N 135.0W   45 KT  50 MPH
 72H  08/0000Z 18.6N 138.0W   40 KT  45 MPH
 96H  09/0000Z 19.9N 143.5W   35 KT  40 MPH
120H  10/0000Z 22.0N 148.3W   35 KT  40 MPH
 
$$
Forecaster Jelsema (CPHC)
 
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