| 11:00 AM AST Mon Sep 10 Location: 25.0N 60.0W Moving: W at 13 mph Min pressure: 962 mb Max sustained: 115 mph https://www.nhc.noaa.gov/#Florence https://www.nhc.noaa.gov/refresh/graphics_at1+shtml/145000.shtml?gm_track#contents https://www.ssd.noaa.gov/PS/TROP/floaters/06L/06L_floater.html http://hurricanecity.com/models/models.cgi?basin=al&year=2018&storm=06 Hurricane Florence Discussion Number 45 NWS National Hurricane Center Miami FL AL062018 1100 AM AST Mon Sep 10 2018 Florence is quickly becoming a powerful hurricane. Satellite images show that the distinct eye has warmed in the center, with convection increasing in the eyewall during the past several hours. The initial wind speed is set to 100 kt, closest to the CIMSS-ADT value. A NOAA Hurricane Hunter will be in the area later this morning for a more accurate estimate. The hurricane is moving over progressively warmer waters over the next couple of days, with water temperatures peaking near 85F. In combination with the low vertical wind shear in the forecast during that time, Florence should continue to strengthen, and all models show it becoming a category 4 hurricane by tomorrow. The corrected-consensus guidance has done quite well with this intensification episode, and I don't see any reason to deviate much from them at this time. As Florence approaches the southeastern United States, there will likely be fluctuations in intensity from eyewall cycles, but even if this occurs, the hurricane's wind field is expected to grow with time, increasing the storm surge and inland wind threats. The bottom line is that there is increasing confidence that Florence will be a large and extremely dangerous hurricane, regardless of its exact intensity. During the last several hours, Florence has turned westward again, estimated at 11 kt. The steering currents are becoming well-defined as as a very strong ridge builds over the northwestern Atlantic Ocean, forcing Florence to move faster toward the west-northwest during the next couple of days. By late Wednesday, a turn toward the northwest is possible due to the orientation of the Atlantic ridge, along with a slight decrease in forward speed due to a new ridge building over the Great Lakes. The various models are shifting around at long range, but the model consensus has barely budged in the past few model cycles. Thus the new NHC forecast is close to the previous one, near the NOAA and FSSE consensus guidance. It is important not to focus on the exact forecast track as average NHC errors at days 4 and 5 are about 140 and 180 n mi, respectively, and dangerous hazards will extend well away from the center. Key Messages: 1. A life-threatening storm surge is likely along portions of the coastlines of South Carolina, North Carolina, and Virginia, and a Storm Surge Watch will likely be issued for some of these areas by Tuesday morning. All interests from South Carolina into the mid-Atlantic region should ensure they have their hurricane plan in place and follow any advice given by local officials. 2. Life-threatening freshwater flooding is likely from a prolonged and exceptionally heavy rainfall event, which may extend inland over the Carolinas and Mid Atlantic for hundreds of miles as Florence is expected to slow down as it approaches the coast and moves inland. 3. Damaging hurricane-force winds are likely along portions of the coasts of South Carolina and North Carolina, and a Hurricane Watch will likely be issued by Tuesday morning. Damaging winds could also spread well inland into portions of the Carolinas and Virginia. 4. Large swells affecting Bermuda and portions of the U.S. East Coast will continue this week, resulting in life-threatening surf and rip currents. FORECAST POSITIONS AND MAX WINDS INIT 10/1500Z 25.0N 60.0W 100 KT 115 MPH 12H 11/0000Z 25.5N 61.9W 115 KT 130 MPH 24H 11/1200Z 26.4N 64.7W 125 KT 145 MPH 36H 12/0000Z 27.8N 67.9W 130 KT 150 MPH 48H 12/1200Z 29.5N 71.0W 130 KT 150 MPH 72H 13/1200Z 33.0N 76.3W 125 KT 145 MPH 96H 14/1200Z 35.0N 79.0W 75 KT 85 MPH...INLAND 120H 15/1200Z 36.0N 80.0W 30 KT 35 MPH...INLAND $$ Forecaster Blake |