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Tropical Storm Henriette Forecast Discussion Number 4
2025-08-05 04:40:15| National Hurricane Center (East Pacific)
Issued at 500 PM HST Mon Aug 04 2025 147 WTPZ43 KNHC 050239 TCDEP3 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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