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Tropical Storm Henriette Discussion Number   5
NWS National Hurricane Center Miami FL       EP082025
1100 PM HST Mon Aug 04 2025
 
The satellite presentation of Henriette has degraded some since the 
previous advisory, with cloud tops warming and the curved band 
structure becoming more fragmented.  The latest subjective Dvorak 
intensity estimates from TAFB and SAB are both 3.0/45 kt, while 
objective estimates from UW-CIMSS have ranged from 37 to 46 kt 
during the past several hours.  Meanwhile, a timely 05/0545Z Metop-C 
ASCAT pass showed several 40-45 kt wind barbs, assisting with 
determining the initial intensity as well as the extent of the 
tropical-storm-force wind radii.  The initial intensity for this 
advisory has been held at 45 kt.

The cyclone is moving west-northwest, or 290 degrees, at 13 knots.  
This general motion is expected to continue during the next day or 
so, as Henriette moves along the southern edge of a subtropical 
ridge to the north.  Between 36 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 an amplifying longwave trough northwest of Hawaii 
erodes the western extent of the subtropical ridge steering the 
cyclone.  The official track forecast closely follows a blend of 
the latest HCCA/TVCE/FSSE consensus guidance, and is very close to 
the track from the previous advisory.

Henriette appears to have a brief window for further intensification 
over the next 12 to 18 hours, as sea surface temperatures hover 
between 26 and 26.5C, mid-level moisture remains sufficient, and 
vertical wind shear stays light.  Little change in strength is 
expected then through 36 hours as the cyclone moves over slightly 
cooler water but close to the 26C isotherm, while shear remains 
light and the mid-levels remain moist. Beyond 36 hours, the cyclone 
is expected to move over progressively cooler waters, with mid-level 
moisture decreasing, and these conditions should lead to gradual 
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 FSSE, which is near the 
middle of the intensity guidance envelope.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  05/0900Z 15.9N 123.1W   45 KT  50 MPH
 12H  05/1800Z 16.5N 125.0W   50 KT  60 MPH
 24H  06/0600Z 17.2N 127.7W   50 KT  60 MPH
 36H  06/1800Z 17.8N 130.6W   50 KT  60 MPH
 48H  07/0600Z 18.2N 133.5W   45 KT  50 MPH
 60H  07/1800Z 18.5N 136.5W   45 KT  50 MPH
 72H  08/0600Z 19.0N 139.6W   40 KT  45 MPH
 96H  09/0600Z 20.3N 144.9W   35 KT  40 MPH
120H  10/0600Z 22.3N 149.8W   35 KT  40 MPH
 
$$
Forecaster Jelsema (CPHC)
 
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