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Tropical Storm Hilda Forecast Discussion Number 1
2021-07-30 22:36:59| National Hurricane Center (East Pacific)
Issued at 300 PM MDT Fri Jul 30 2021 000 WTPZ43 KNHC 302036 TCDEP3 Tropical Storm Hilda Discussion Number 1 NWS National Hurricane Center Miami FL EP082021 300 PM MDT Fri Jul 30 2021 A pair of ASCAT passes from a few hours ago indicated that the area of low pressure located about 800 miles south-southwest of the southern tip of the Baja California peninsula has strengthened, and is producing 35-40 kt winds on its east side. In addition, satellite images show a fairly persistent area of showers and thunderstorms on the south side of the circulation and the center appears to be fairly well defined in recent visible images. Based on these data, advisories are now being initiated on Tropical Storm Hilda and the initial intensity is estimated to be 40 kt. Hilda is moving westward at about 14 kt and is embedded in the flow on the south side of a sprawling subtropical ridge that extends from the south-central U.S. westward across the subtropical eastern Pacific. A general west-northwestward motion at about the same forward speed is expected during the next day or two as the synoptic pattern holds. After that time, a decrease in forward speed is predicted due to a combination of the subtropical ridge weakening and the interactions with the areas of low pressure to the east and west of Hilda. The ECMWF is the slowest model at long range due to it showing the most interaction with the low to Hildas east. The NHC track forecast lies generally near the model consensus and roughly between the GFS and ECMWF models. Hilda appears to be in generally conducive conditions for strengthening with SSTs currently around 28 C, abundant mid-level moisture, and fairly low wind shear. Given that these conditions are expected to persist for another couple of days, steady strengthening is forecast during that time period and Hilda is predicted to become a hurricane in 24 to 36 hours. Beyond a couple of days, however, moderate easterly shear, progressively drier air, and decreasing SSTs should end the strengthening trend and induce gradual weakening of the cyclone. The NHC intensity forecast lies near the middle of the guidance envelope, closest to the intensity model consensus IVCN. FORECAST POSITIONS AND MAX WINDS INIT 30/2100Z 12.1N 113.6W 40 KT 45 MPH 12H 31/0600Z 12.6N 115.4W 50 KT 60 MPH 24H 31/1800Z 13.2N 117.6W 60 KT 70 MPH 36H 01/0600Z 13.8N 119.7W 70 KT 80 MPH 48H 01/1800Z 14.3N 121.6W 75 KT 85 MPH 60H 02/0600Z 14.9N 123.1W 75 KT 85 MPH 72H 02/1800Z 15.3N 124.4W 70 KT 80 MPH 96H 03/1800Z 16.6N 126.4W 65 KT 75 MPH 120H 04/1800Z 18.3N 129.5W 55 KT 65 MPH $$ Forecaster Cangialosi
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