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Hurricane Florence Forecast Discussion Number 61
2018-09-14 16:49:57| National Hurricane Center (Atlantic)
Issued at 1100 AM EDT Fri Sep 14 2018 326 WTNT41 KNHC 141449 TCDAT1 Hurricane Florence Discussion Number 61 NWS National Hurricane Center Miami FL AL062018 1100 AM EDT Fri Sep 14 2018 Florence's satellite signature remains very impressive even though the eye is now located just inland over southeastern North Carolina near Cape Fear. However, land interaction has taken its toll on the inner-core circulation, and the previously well-defined eye in radar imagery has shrunk and become filled with rain echoes. The advisory intensity has been lowered to 70 kt based on earlier reports from an Air Force Reserve reconnaissance aircraft, NOAA Doppler weather radar velocity data from Wilmington and Morehead City, and nearby surface observations. The central pressure of 958 mb is based on observations from a NOAA NOS site in Wrightsville Beach and a Weatherflow private station in Federal Point. Another Air Force Hurricane Hunter aircraft will be sampling the portion of Florence's circulation over water during the next few hours. Florence has turned west-southwestward and the motion estimate is now 245/03 kt. Florence is expected to remain embedded within a weak steering flow regime within a weakness in the subtropical ridge, resulting in a slow westward motion for the next 36-48 hours across South Carolina. As a shortwave trough currently located over the eastern Great Lakes to Maryland moves eastward away from the region over the next 2 days, the ridge will begin to build back in and shift eastward, allowing Florence or its remnants to gradually turn northward over the weekend, and then move northeastward into the mid-latitude westerlies as an extratropical low. The new NHC forecast track is similar to the previous advisory, and is close to the middle of the model guidance envelope. Wind data from the earlier aircraft mission, along with Doppler radar velocity data and surface observations, indicate that Florence has weakened. Additional slow weakening is expected today as the center of Florence moves farther inland, with more rapid weakening forecast over the weekend as Florence moves westward across South Carolina. The new NHC intensity forecast is a little lower than the previous advisory, and closely follows the trend of Decay SHIPS model. Although coastal storm surge flooding will gradually subside later today, it cannot be emphasized enough that another serious hazard associated with slow-moving Florence is and will be extremely heavy rainfall. More than 14 inches of rain has already fallen in many areas across southeastern North Carolina, and more rain is still to come, which will cause disastrous flooding that will spread inland through the weekend. Key Messages: 1. A life-threatening storm surge is already occurring along portions of the North Carolina coast and will continue through today and tonight. This surge is also likely along portions of the South Carolina coast. The greatest storm surge inundation is expected between Cape Fear and Cape Hatteras, including the Neuse and Pamlico Rivers and western Pamlico Sound. 2. Life-threatening, catastrophic flash flooding and prolonged significant river flooding are likely over portions of the Carolinas and the southern and central Appalachians through early next week, as Florence is expected to slow down while it moves inland. 3. Damaging hurricane-force winds are occurring along portions of the North Carolina coast and are expected to spread to portions of the South Carolina coast later today. Strong winds could also spread inland into portions of the Carolinas over the next couple of days. 4. 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 14/1500Z 34.0N 78.0W 70 KT 80 MPH...INLAND 12H 15/0000Z 33.9N 78.9W 65 KT 75 MPH...INLAND 24H 15/1200Z 33.8N 79.7W 55 KT 65 MPH...INLAND 36H 16/0000Z 33.9N 80.8W 35 KT 40 MPH...INLAND 48H 16/1200Z 34.7N 82.0W 25 KT 30 MPH...INLAND 72H 17/1200Z 37.7N 83.0W 25 KT 30 MPH...POST-TROP/INLAND 96H 18/1200Z 41.2N 78.4W 20 KT 25 MPH...POST-TROP/INLAND 120H 19/1200Z 44.4N 68.7W 20 KT 25 MPH...POST-TROP/INLAND $$ Forecaster Stewart
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