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Tropical Storm Henriette Forecast Discussion Number 13
2025-08-07 10:46:30| National Hurricane Center (East Pacific)
Issued at 1100 PM HST Wed Aug 06 2025 955 WTPZ43 KNHC 070846 TCDEP3 Tropical Storm Henriette Discussion Number 13 NWS National Hurricane Center Miami FL EP082025 1100 PM HST Wed Aug 06 2025 Satellite images indicate that a small burst of deep convection has developed just to the northwest of Henriettes low-level center this evening, after several hours with not much more than a shallow cloud swirl. The most recent subjective Dvorak current intensity estimate from TAFB was 3.0/45 kt, while the objective estimates from UW-CIMSS ranged between 32 to 42 kt over the past several hours. A timely 07/0645Z Metop-C ASCAT pass depicted several 40 kt wind barbs, with a single 4045 kt wind barb noted north of the low-level center. The initial intensity for this advisory will be held at 45 kt, utilizing the ASCAT data while accounting for some undersampling and a known low bias at higher speeds. The cyclone is moving westward, or 275 degrees, at 14 kt. This general motion is expected to persist through Thursday, as Henriette continues to be steered by a strengthening subtropical ridge to its north. A gradual turn toward the west-northwest and eventually northwest is anticipated Friday and over the weekend, as an amplifying longwave trough northwest of Hawaii begins to erode the western extent of the subtropical ridge. The northwestward motion is expected to continue into early next week. The official track forecast remains closely aligned with the latest multi-model consensus aids and is nearly identical to the previous advisory. Henriette will be moving over gradually cooling sea surface temperatures near 24C, while the environmental humidities surrounding the cyclone will drop below 50 percent. Despite these hostile thermodynamic conditions, Henriettes well-established circulation is likely to remain resilient due to the low-shear environment the cyclone will be transiting through. As a result, only a slight weakening is forecast tonight, followed by little change in strength during the next few days. If Henriette can survive the passage over the cool waters, as persistently suggested by the GFS and ECMWF models for several days now, re-intensification appears likely over the weekend and into early next week as sea surface temperatures warm to levels conducive for strengthening. The official forecast continues to reflect this, bringing Henriette to hurricane strength by 120 hours. The intensity forecast is mostly unchanged and remains aligned best with the dynamical intensity consensus aid HCCA and the regional hurricane models. FORECAST POSITIONS AND MAX WINDS INIT 07/0900Z 18.4N 133.9W 40 KT 45 MPH 12H 07/1800Z 18.6N 136.2W 40 KT 45 MPH 24H 08/0600Z 19.1N 139.3W 40 KT 45 MPH 36H 08/1800Z 19.8N 142.3W 40 KT 45 MPH 48H 09/0600Z 20.7N 145.1W 40 KT 45 MPH 60H 09/1800Z 21.9N 147.7W 40 KT 45 MPH 72H 10/0600Z 23.3N 150.1W 45 KT 50 MPH 96H 11/0600Z 26.9N 154.8W 55 KT 65 MPH 120H 12/0600Z 30.2N 158.9W 65 KT 75 MPH $$ Forecaster Jelsema (CPHC)
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