000 WTPZ43 KNHC 050842 TCDEP3 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)
Source link