388 WTPA43 PHFO 091444 TCDCP3 Tropical Depression Henriette Discussion Number 22 NWS Central Pacific Hurricane Center Honolulu HI EP082025 Issued by NWS National Hurricane Center Miami FL 500 AM HST Sat Aug 09 2025 Convection has persisted and perhaps increased slightly in areal coverage and organization over the last 6 hours. A recent AMSR2 microwave pass paints a similar picture to the GOES-18 imagery, with the convection confined to the northwest quadrant and the center located near the edge of the convection. The latest subjective Dvorak classifications are 1.5/25 kt from JTWC and PHFO, and 1.0 from SAB. The UW-CIMSS objective intensity estimates are higher than the subjective estimates, mostly in the 30-35 kt range. An earlier ASCAT-B pass from 0655 UTC indicates that peak winds were at least 30 kt. The initial intensity is held at 30 kt for this advisory, but Henriette is close to regaining tropical storm strength. The initial motion is toward the west-northwest, or 300 degrees at 12 kt. The global models show that Henriette will round the southwestern periphery of the subtropical ridge tonight, which will cause the cyclone to turn toward the northwest, in between the ridge and an approaching large deep-layer trough to the west. In a couple days, the trough will become stationary or even retrograde westward. This steering pattern favors a continued northwestward motion through the forecast period. The NHC track forecast is very similar to the previous one and lies near the middle of the tightly clustered consensus aids. Henriette will move over gradually warming sea-surface temperatures (SSTs) and through gradually cooling upper-level temperatures now through the next 72 h. SSTs currently near 24.5 to 25C are forecast to warm to the 26.5 to 27C range along the cyclone's path. There is some uncertainty as to how the expected moderate wind shear may affect the cyclone, especially given how dry the mid-troposphere will continue to be along Henriette's path. The shear direction could be close to the direction of the cyclone's motion, so the shear shouldn't be as much of a negative factor as the dry air. Given all the competing factors mentioned above, slow strengthening seems likely over the next few days. The latest NHC intensity forecast is similar to the previous one and is near the middle of the guidance envelope. Beyond day 3, wind shear should increase, and Henriette will likely reach cooler water again by day 4. These factors should cause the system to lose its convection and become post-tropical in 4 to 5 days. FORECAST POSITIONS AND MAX WINDS INIT 09/1500Z 21.4N 146.8W 30 KT 35 MPH 12H 10/0000Z 22.3N 148.5W 35 KT 40 MPH 24H 10/1200Z 23.9N 150.6W 40 KT 45 MPH 36H 11/0000Z 25.8N 152.8W 45 KT 50 MPH 48H 11/1200Z 27.9N 155.3W 50 KT 60 MPH 60H 12/0000Z 29.9N 157.9W 55 KT 65 MPH 72H 12/1200Z 32.0N 160.4W 55 KT 65 MPH 96H 13/1200Z 36.1N 165.0W 40 KT 45 MPH 120H 14/1200Z 40.3N 168.5W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Hagen
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