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Tropical Storm Beta Forecast Discussion Number 18
2020-09-22 04:47:24| National Hurricane Center (Atlantic)
Issued at 1000 PM CDT Mon Sep 21 2020 000 WTNT42 KNHC 220247 TCDAT2 Tropical Storm Beta Discussion Number 18 NWS National Hurricane Center Miami FL AL222020 1000 PM CDT Mon Sep 21 2020 There has been a recent increase in convection along the Texas coast just to the north of Beta's center this evening. A blend of flight-level and SFMR winds from an Air Force Reserve reconnaissance aircraft indicate that Beta's peak intensity remains around 40 kt. The aircraft has reported a minimum central pressure of around 999 mb, which is unchanged from earlier today. West-southwesterly vertical wind shear and land interaction should gradually weaken the cyclone over the next couple of days. The NHC intensity forecast is a little above model guidance through 24 hours since a significant portion of the circulation is forecast to remain over water. Strong vertical wind shear is expected to prevent re-strengthening when Beta moves near or just offshore of the Upper Texas coast in a couple of days. Beta is moving northwestward or 325/3 kt. The tropical storm should move just inland along the central Texas coast overnight, but it is expected to become nearly stationary on Tuesday as steering currents collapse. A weak trough over the south-central United States should begin to steer Beta east-northeastward Tuesday night and Wednesday, and a northeastward motion at a slightly faster forward speed should continue until dissipation in 72-96 hours. The latest NHC track forecast is very similar to the previous advisory and is a blend of the latest GFS and ECMWF models. Key Messages: 1. The expected slow motion of Beta will produce a long duration rainfall event from the middle Texas coast to southeast Louisiana. Flash, urban, and minor river flooding is likely. Rainfall will also spread northward into the ArkLaTex region and east into the Lower Mississippi Valley and portions of the Southeast through the end of the week. Flash, urban, and isolated minor river flooding is possible. 2. There is the danger of life-threatening storm surge near times of high tide through Tuesday along portions of the Texas and Louisiana coasts within the storm surge warning areas. Residents in these areas should follow advice given by local officials. 3. Tropical-storm-force winds will spread westward across the Texas coast through Tuesday. FORECAST POSITIONS AND MAX WINDS INIT 22/0300Z 28.4N 96.3W 40 KT 45 MPH 12H 22/1200Z 28.6N 96.3W 35 KT 40 MPH...INLAND 24H 23/0000Z 28.8N 96.0W 35 KT 40 MPH...INLAND 36H 23/1200Z 29.1N 95.0W 30 KT 35 MPH...OVER WATER 48H 24/0000Z 29.5N 93.8W 30 KT 35 MPH...OVER WATER 60H 24/1200Z 30.4N 92.3W 25 KT 30 MPH...INLAND 72H 25/0000Z 31.7N 90.7W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 26/0000Z...DISSIPATED $$ Forecaster Brown
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Category:Transportation and Logistics