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Tropical Storm Hilda Forecast Discussion Number 2
2021-07-31 04:33:04| National Hurricane Center (East Pacific)
Issued at 900 PM MDT Fri Jul 30 2021 000 WTPZ43 KNHC 310232 TCDEP3 Tropical Storm Hilda Discussion Number 2 NWS National Hurricane Center Miami FL EP082021 900 PM MDT Fri Jul 30 2021 Satellite imagery indicates that Hilda has gotten a little better organized during the past several hours, with the low-level center now near the eastern end of a long convective band that is present in the southwestern semicircle. Satellite intensity estimates are 35 kt from TAFB and 45 kt from SAB, and based on these the initial intensity remains 40 kt. The storm is currently in an environment of light northwesterly vertical wind shear with the bulk of the outflow to the south. Conditions generally appear favorable for strengthening during the next 72 h or so, as Hilda is expected to be over warm sea surface temperatures and in an environment of light to moderate shear. Based on this, the first part of the intensity forecast is unchanged from the previous forecast and calls for Hilda to become a hurricane between 24 and 36 h and peak in intensity around 60 h. After that, the forecast becomes less confident. The cyclone is expected to move over decreasing sea surface temperatures after 72 h, and this should cause gradual weakening as indicated in the official forecast. The official forecast for this period has been nudged downward due to the forecast motion over cooler water. However, the GFS and ECMWF models suggest the possibility that Hilda will interact with other nearby systems - the GFS forecasting with Tropical Depression Nine-E to the west and the ECMWF forecasting interaction with a disturbance to the east. Should either of these interactions occur, Hilda could weaken at a different rate than currently forecast. The initial motion is 290/13. Hilda is located on the south side of a subtropical ridge, and if the storm does not interact with other nearby weather systems a general west-northwestward motion with a decrease in forward speed is expected through the forecast period. The new forecast track is shifted a little north of the previous track, and it lies just to the south of the various consensus models. If Hilda does interact with either Tropical Depression Nine-E or the disturbance to the east, it will lead to erratic motion. FORECAST POSITIONS AND MAX WINDS INIT 31/0300Z 13.2N 114.6W 40 KT 45 MPH 12H 31/1200Z 13.5N 116.3W 50 KT 60 MPH 24H 01/0000Z 14.1N 118.4W 60 KT 70 MPH 36H 01/1200Z 14.7N 120.3W 70 KT 80 MPH 48H 02/0000Z 15.3N 122.0W 75 KT 85 MPH 60H 02/1200Z 15.8N 123.3W 75 KT 85 MPH 72H 03/0000Z 16.5N 124.8W 70 KT 80 MPH 96H 04/0000Z 18.0N 127.0W 60 KT 70 MPH 120H 05/0000Z 19.5N 131.0W 50 KT 60 MPH $$ Forecaster Beven
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