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Hurricane Hilda Forecast Discussion Number 7
2021-08-01 10:37:01| National Hurricane Center (East Pacific)
Issued at 200 AM PDT Sun Aug 01 2021 000 WTPZ43 KNHC 010836 TCDEP3 Hurricane Hilda Discussion Number 7 NWS National Hurricane Center Miami FL EP082021 200 AM PDT Sun Aug 01 2021 Hilda's strengthening last evening was short lived. Infrared and water vapor imagery show high-level clouds from a weather disturbance to the east impinging on the eastern side of Hilda's circulation, suggestive of moderate easterly shear. In fact, 85-GHz SSMIS data from 0241 UTC shows that the microwave presentation has degraded significantly, with most of the deep convection displaced to the west of the low-level center. Hilda's initial intensity is being held at 75 kt based on Dvorak CI numbers of 4.5 from TAFB and SAB, although that estimate could be generous. Hilda continues to move west-northwestward, or 285/9 kt, to the south of a subtropical ridge which is expected to build westward over the Pacific during the next few days. Despite the placement of this ridge, the dynamical models indicate that Hilda is likely to have some degree of binary interaction with the disturbance to its east and thus take on a northwestward heading on days 2 and 3. After the interaction, the ridge should then cause Hilda to turn back toward the west-northwest and then west by days 4 and 5. While there are some model outliers, the spread among the guidance has actually decreased over the past 24 hours. The updated NHC track forecast is not too different from the previous forecast, except that it is a little slower to account for recent model trends. The moderate easterly shear affecting Hilda is unlikely to abate much during the next couple of days, especially as the distance between the hurricane and the disturbance to the east decreases. Still, Hilda will remain over relatively warm waters during that period, and the models suggest that the hurricane will either maintain its current intensity or strengthen slightly through 48 hours. Hilda is then expected to move over waters colder than 26 degrees Celsius, causing a steady weakening trend through the end of the forecast period. The new NHC intensity forecast is a little lower than the previous forecast to account for the current structure of the cyclone and the latest model solutions, although the forecast intensities are not as low as what is shown by the HCCA and IVCN consensus aids. FORECAST POSITIONS AND MAX WINDS INIT 01/0900Z 14.5N 119.6W 75 KT 85 MPH 12H 01/1800Z 14.8N 120.8W 80 KT 90 MPH 24H 02/0600Z 15.3N 122.1W 80 KT 90 MPH 36H 02/1800Z 15.9N 123.3W 80 KT 90 MPH 48H 03/0600Z 16.7N 124.3W 75 KT 85 MPH 60H 03/1800Z 17.6N 125.4W 65 KT 75 MPH 72H 04/0600Z 18.7N 126.9W 55 KT 65 MPH 96H 05/0600Z 20.1N 130.9W 45 KT 50 MPH 120H 06/0600Z 20.7N 135.3W 35 KT 40 MPH $$ Forecaster Berg
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