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Tropical Depression Twenty-Four-E Forecast Discussion Number 1
2018-10-20 11:06:03| National Hurricane Center (East Pacific)
Issued at 400 AM CDT Sat Oct 20 2018 000 WTPZ44 KNHC 200905 CCA TCDEP4 Tropical Depression Twenty-Four-E Discussion Number 1...Corrected NWS National Hurricane Center Miami FL EP242018 400 AM CDT Sat Oct 20 2018 Corrected advisory number from 2 to 1 Various satellite data indicate that the area of low pressure that NHC has been monitoring off the coast of southern Mexico for thew past few days has acquired enough convective organization to be designated as a tropical depression, the twenty-fourth one of the very busy 2018 eastern North Pacific hurricane season. Although the depression is a sheared system, some banding features have recently developed south of the center, while overshooting cloud tops just west of the center are quite cold -85 to -91 deg C). The initial intensity is set to 30 kt based on a satellite intensity estimate of T2.0/30 kt from both TAFB and SAB. The initial motion estimate is 280/08 kt, based primarily on passive microwave fixes and GOES-16 nighttime imagery. A gradual turn toward the west-northwest is expected by this afternoon, followed by a slower northwestward motion on Sunday as the system moves along the southwestern periphery of a weakening mid-level ridge. A slow northwestward motion is expected to continue into early next week while the ridge to the north changes little. On days 4 and 5, however, a series of weak shortwave troughs are forecast to move through the larger scale southwesterly flow locked in over the southwestern U.S. and northern Mexico, causing an erosion of the western portion of the ridge, which should allow the cyclone to gradually recurve northward and north-northeastward. The NHC model guidance is in good agreement overall on this developing track scenario, and the official forecast track lies between the HCCA and TVCE track consensus aids. The depression is expected to steadily strengthen during the next 96 hours due to very favorable environmental conditions consisting of low vertical wind shear (less than 10 kt), high amounts of mid-level moisture, and warm 28-30 deg C SSTs. As a result, the cyclone is expected to become a tropical storm later this morning, a hurricane by Sunday night, and be near major hurricane strength by Wednesday. Given the very favorable conditions expected on Sunday and Monday, there is a fair chance of rapid intensification occurring similar to that depicted by the COAMPS-TC and HMON models, which bring the cyclone to category-4 status around 72 hours. The NHC official intensity forecast near the HCCA and IVCN consensus models through 96 hours, and then a little above the guidance at 120 hours despite an increase in the shear expected at that time. FORECAST POSITIONS AND MAX WINDS INIT 20/0900Z 15.1N 104.9W 30 KT 35 MPH 12H 20/1800Z 15.5N 105.7W 40 KT 45 MPH 24H 21/0600Z 15.9N 106.6W 50 KT 60 MPH 36H 21/1800Z 16.5N 107.4W 60 KT 70 MPH 48H 22/0600Z 17.1N 108.0W 75 KT 85 MPH 72H 23/0600Z 18.0N 109.0W 90 KT 105 MPH 96H 24/0600Z 19.2N 109.4W 100 KT 115 MPH 120H 25/0600Z 21.7N 108.5W 95 KT 110 MPH $$ Forecaster Stewart
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