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Tropical Storm Narda Forecast Discussion Number 6
2025-09-23 04:43:58| National Hurricane Center (East Pacific)
Issued at 900 PM CST Mon Sep 22 2025 000 WTPZ44 KNHC 230243 TCDEP4 Tropical Storm Narda Discussion Number 6 NWS National Hurricane Center Miami FL EP142025 900 PM CST Mon Sep 22 2025 The satellite presentation of Narda has continued to improve since the previous advisory, with deep convection featuring cloud tops colder than -80C bursting over the low-level center. A recent 0034 UTC WSFM microwave image confirms the improved organization, showing Narda beginning to develop an inner-core structure. Subjective Dvorak estimates from TAFB and SAB were both 3.5/55 kt, while objective estimates from UW-CIMSS ranged from 44 to 60 kt. A blend of these data, along with the improved satellite appearance, supports raising the initial intensity to 55 kt for this advisory. Narda is moving due west, or 270 degrees, at 11 kt. This motion is expected to continue for the next several days as the cyclone is steered by a strengthening subtropical ridge to its north and northwest. By late in the period, a mid-level low over southern California is forecast to erode the eastern portion of the ridge, causing the cyclone to slow down and turn northwestward around day 5. The official forecast track has been adjusted slightly south of the previous prediction during the next couple of days to account for the westward motion that has now begun, but it remains very close to the prior forecast from day 3 onward. The track forecast follows a blend of the HCCA, TVCE, and FSSE consensus aids, as well as the Google DeepMind/NOAA Eagle AI guidance. Narda will remain embedded within a moist air mass, over very warm waters, and in an environment of light to moderate easterly shear during the next couple of days. These factors should support steady strengthening. The latest GFS- and ECMWF-based SHIPS guidance indicates about a 50 percent probability of a 25-kt increase within 24 hours, and the intensity forecast reflects this. Narda is expected to become a hurricane later tonight or early Tuesday and could approach major hurricane status within a couple of days. By late in the forecast period, however, Narda will move into an environment with mid-level humidity below 50 percent and over waters cooler than 26C, which should result in steady to rapid weakening by day 5. The official intensity forecast remains near the upper end of the guidance envelope and is most closely aligned with the SHIPS and HCCA aids. FORECAST POSITIONS AND MAX WINDS INIT 23/0300Z 15.9N 105.1W 55 KT 65 MPH 12H 23/1200Z 15.9N 106.8W 70 KT 80 MPH 24H 24/0000Z 15.8N 109.1W 80 KT 90 MPH 36H 24/1200Z 15.7N 111.4W 90 KT 105 MPH 48H 25/0000Z 15.6N 113.8W 95 KT 110 MPH 60H 25/1200Z 15.7N 116.4W 95 KT 110 MPH 72H 26/0000Z 16.1N 118.9W 95 KT 110 MPH 96H 27/0000Z 17.1N 122.9W 90 KT 105 MPH 120H 28/0000Z 18.7N 125.1W 70 KT 80 MPH $$ Forecaster Jelsema (CPHC)
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