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Tropical Storm Beta Forecast Discussion Number 19
2020-09-22 10:57:56| National Hurricane Center (Atlantic)
Issued at 400 AM CDT Tue Sep 22 2020 949 WTNT42 KNHC 220857 TCDAT2 Tropical Storm Beta Discussion Number 19 NWS National Hurricane Center Miami FL AL222020 400 AM CDT Tue Sep 22 2020 Beta's center has continued to move farther inland since making landfall on the southern end of the Matagorda Peninsula around 10 PM CDT last evening. There have not been any surface observations of sustained tropical-storm-force winds, and an earlier ASCAT pass indicated that winds over the water had decreased to near 35 kt. That is Beta's estimated intensity at the moment, with the assumption that those winds are still occurring somewhere over water or within the deep convection near the center. Beta has been moving northwestward, or 315/3 kt. Steering currents around the storm are now collapsing, and Beta is expected to meander during the next 12-24 hours. By this time tomorrow, however, a mid-level trough over west Texas is forecast to begin moving eastward and should scoop Beta up, causing the storm to move toward the east-northeast near or just inland of the upper Texas coast through 36 hours. After that time, Beta is expected to turn northeastward, moving farther inland across Louisiana and Mississippi before dissipating in about 4 days. Because Beta has moved a little farther inland than expected, much of the model trackers have shifted northward, and now only the UKMET and its ensemble mean show Beta's center re-emerging over the extreme northwestern Gulf of Mexico. The new NHC track forecast has been adjusted northward accordingly and generally lies between the HCCA aid and the TVCN multi-model consensus. Now that Beta's center may not move back out over the Gulf, the intensity guidance indicates that the cyclone will gradually weaken during the next few days. However, since a part of the circulation will remain over water and the system could still produce deep convection, the NHC forecast shows Beta maintaining tropical storm status for another 12 hours or so (a scenario which is above all of the guidance). Beta should weaken to a tropical depression in about 24 hours, and it is expected to become a remnant low in 2-3 days when vertical shear is expected to be well over 30 kt. Key Messages: 1. Significant flash and urban flooding is occurring and will continue for the middle and upper Texas coast today. The slow motion of Beta will continue to produce a long duration rainfall event from the middle Texas coast to southern Louisiana. Flash, urban, and minor river flooding is likely. Periods of rainfall will continue into the ArkLaTex region and spread 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. Storm surge flooding will continue throughout the morning, around the times of high tide along portions of the Texas coast within the storm surge warning areas. Residents in these areas should continue to follow advice of local officials. 3. Tropical-storm-force winds will continue near portions of the Texas coast within the warning area today. FORECAST POSITIONS AND MAX WINDS INIT 22/0900Z 28.8N 96.7W 35 KT 40 MPH...INLAND 12H 22/1800Z 28.8N 96.5W 35 KT 40 MPH...INLAND 24H 23/0600Z 29.1N 95.6W 30 KT 35 MPH...INLAND 36H 23/1800Z 29.8N 94.3W 30 KT 35 MPH...INLAND 48H 24/0600Z 30.8N 92.8W 25 KT 30 MPH...INLAND 60H 24/1800Z 32.1N 90.9W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 25/0600Z 33.6N 89.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 26/0600Z...DISSIPATED $$ Forecaster Berg
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Category:Transportation and Logistics