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Tropical Depression Florence Forecast Discussion Number 68
2018-09-16 10:48:09| National Hurricane Center (Atlantic)
Issued at 500 AM EDT Sun Sep 16 2018 635 WTNT41 KNHC 160848 TCDAT1 Tropical Depression Florence Discussion Number 68 NWS National Hurricane Center Miami FL AL062018 500 AM EDT Sun Sep 16 2018 Surface observations indicate that there are no longer any sustained tropical-storm-force winds as the center of Florence has moved farther inland over South Carolina. Therefore, the system is being downgraded to a tropical depression at this time. Maximum winds are estimated to be 30 kt. Continued gradual weakening is likely, and the numerical guidance suggests that the cyclone will be disorganized enough to become a remnant low in 36 hours or so. In 72 hours, global models indicate that the system will become an extratropical cyclone, with some strengthening due to baroclinic processes as it moves over the Atlantic in 3-5 days. This scenario is very similar to that from the previous advisory. The forward speed of Florence has increased somewhat early this morning and the motion is now near 280/7 kt. The high pressure system that has been blocking the forward progress of Florence is predicted to slide eastward and southeastward during the next day or so. As a result, over the next couple of days, Florence is expected to move northwestward, northward, and then north-northeastward around the periphery of the high. Later in the forecast period, Florence should accelerate east-northeastward in the mid-latitude westerlies. The official track forecast is similar to the previous one and close to the dynamical model consensus. This will be the last advisory issued by the National Hurricane Center on Florence. Future information on Florence can be found in Public Advisories issued by the Weather Prediction Center beginning at 11 AM EDT, under AWIPS header TCPAT1, WMO header WTNT31 KWNH, and on the web at https://www.wpc.ncep.noaa.gov. Key Messages: 1. Life-threatening, catastrophic flash floods and prolonged significant river flooding are likely over portions of the Carolinas and the southern to central Appalachians from western North Carolina into west-central Virginia and far eastern West Virginia through early this week, as Florence continues to move slowly inland. In addition to the flash flood and flooding threat, landslides are also possible in the higher terrain of the southern and central Appalachians across western North Carolina into southwest Virginia. 2. Large swells affecting Bermuda, portions of the U.S. East Coast, and the northwestern and central Bahamas will continue this week, resulting in life-threatening surf and rip currents. FORECAST POSITIONS AND MAX WINDS INIT 16/0900Z 33.8N 81.4W 30 KT 35 MPH...INLAND 12H 16/1800Z 34.7N 82.5W 30 KT 35 MPH...INLAND 24H 17/0600Z 36.7N 83.6W 25 KT 30 MPH...INLAND 36H 17/1800Z 38.7N 82.6W 20 KT 25 MPH...POST-TROP/REMNT LOW 48H 18/0600Z 39.8N 79.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 72H 19/0600Z 42.0N 68.0W 30 KT 35 MPH...POST-TROP/EXTRATROP 96H 20/0600Z 43.5N 55.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 120H 21/0600Z 46.0N 40.0W 40 KT 45 MPH...POST-TROP/EXTRATROP $$ Forecaster Pasch
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