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Tropical Depression Henriette Discussion Number  21
NWS Central Pacific Hurricane Center Honolulu HI   EP082025
Issued by NWS National Hurricane Center Miami FL
1100 PM HST Fri Aug 08 2025
 
Deep convection that developed north of Henriette’s well-defined 
low-level circulation earlier today has persisted during the past 
several hours. Given this sustained convective activity and the 
presence of a closed surface circulation, Henriette is being 
reclassified as a tropical depression. A Metop-B ASCAT pass at 0655 
UTC indicated peak winds up to 30 kt in the northern semicircle, 
supporting the initial intensity estimate of 30 kt.

The initial motion is toward the west-northwest at about 13 kt, 
steered by a low- to mid-level ridge to its north. This general 
motion is expected to continue through the next 24 hours. From 24 to 
72 hours, the cyclone should gradually turn toward the northwest as 
it approaches a weakness in the ridge caused by an amplifying 
upper-level trough well northwest of Hawaii. Between 72 and 96 
hours, Henriette is forecast to turn toward the north-northwest as 
the trough becomes the primary steering feature. The updated track 
forecast remains very similar to the previous advisory and is near 
the middle of the tightly clustered consensus aids.

The system is currently located over sea surface temperatures near 
24 degrees C and within a stable, dry mid- to upper-level 
environment, which should limit convective coverage in the near 
term. However, global model guidance indicates that the cyclone will 
traverse an area of slightly warmer water between 24 and 72 hours. 
At the same time, upper-level divergence is forecast to increase in 
association with the approaching trough, which should enhance 
instability and support gradual strengthening beginning late 
Saturday and continuing into early next week. After that time, 
upper-level divergence is forecast to diminish, vertical shear will 
increase, and water temperatures will cool sharply. This loss of 
outflow support and more hostile environment should result in steady 
weakening, with Henriette expected to become a post-tropical remnant 
low by 120 h and dissipate soon thereafter as it is absorbed by a 
larger mid-latitude system. The new intensity forecast is nearly 
unchanged from the previous NHC forecast and lies near the middle- 
to upper-end of the guidance envelope.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  09/0900Z 20.7N 145.7W   30 KT  35 MPH
 12H  09/1800Z 21.6N 147.4W   30 KT  35 MPH
 24H  10/0600Z 23.0N 149.6W   35 KT  40 MPH
 36H  10/1800Z 24.8N 151.6W   45 KT  50 MPH
 48H  11/0600Z 26.8N 154.2W   50 KT  60 MPH
 60H  11/1800Z 28.7N 156.7W   55 KT  65 MPH
 72H  12/0600Z 30.8N 159.2W   55 KT  65 MPH
 96H  13/0600Z 35.2N 163.7W   45 KT  50 MPH
120H  14/0600Z 39.0N 167.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
 
$$
Forecaster Gibbs (CPHC)
 
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