Hurricane Florence Advisory Number 54 NWS National Hurricane Center Miami FL AL062018 500 PM EDT Wed Sep 12 2018 ...FLORENCE MOVING STEADILY TOWARD THE CAROLINA COASTAL AREAS... ...LIFE-THREATENING STORM SURGE AND RAINFALL EXPECTED... SUMMARY OF 500 PM EDT...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...30.9N 72.5W ABOUT 385 MI...615 KM SE OF WILMINGTON NORTH CAROLINA ABOUT 420 MI...675 KM ESE OF MYRTLE BEACH SOUTH CAROLINA MAXIMUM SUSTAINED WINDS...120 MPH...195 KM/H PRESENT MOVEMENT...NW OR 315 DEGREES AT 16 MPH...26 KM/H MINIMUM CENTRAL PRESSURE...949 MB...28.03 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: None. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Storm Surge Warning is in effect for... * South Santee River South Carolina to Duck North Carolina * Albemarle and Pamlico Sounds, including the Neuse and Pamlico Rivers A Storm Surge Watch is in effect for... * Edisto Beach South Carolina to South Santee River South Carolina * North of Duck North Carolina to the North Carolina/Virginia border A Hurricane Warning is in effect for... * South Santee River South Carolina to Duck North Carolina * Albemarle and Pamlico Sounds A Hurricane Watch is in effect for... * Edisto Beach South Carolina to South Santee River South Carolina A Tropical Storm Warning is in effect for... * North of Duck North Carolina to the North Carolina/Virginia border A Tropical Storm Watch is in effect for... * North of the North Carolina/Virginia border to Cape Charles Light Virginia * Chesapeake Bay south of New Point Comfort Interests elsewhere in the southeastern and mid-Atlantic states should monitor the progress of Florence. A Storm Surge Warning means there is a danger of life-threatening inundation, from rising water moving inland from the coastline, during the next 36 hours in the indicated locations. For a depiction of areas at risk, please see the National Weather Service Storm Surge Watch/Warning Graphic, available at hurricanes.gov. This is a life-threatening situation. Persons located within these areas should take all necessary actions to protect life and property from rising water and the potential for other dangerous conditions. Promptly follow evacuation and other instructions from local officials. A Storm Surge Watch means there is a possibility of life- threatening inundation, from rising water moving inland from the coastline, in the indicated locations during the next 48 hours. A Hurricane Warning means that hurricane conditions are expected somewhere within the warning area. A warning is typically issued 36 hours before the anticipated first occurrence of tropical-storm- force winds, conditions that make outside preparations difficult or dangerous. Preparations to protect life and property should be rushed to completion. A Hurricane Watch means that hurricane conditions are possible within the watch area. A watch is typically issued 48 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous. A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within 36 hours. A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours. For storm information specific to your area, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office. DISCUSSION AND OUTLOOK ---------------------- At 500 PM EDT (2100 UTC), the center of Hurricane Florence was located near latitude 30.9 North, longitude 72.5 West. Florence is moving toward the northwest near 16 mph (26 km/h), and this general motion, accompanied by a gradual decrease in forward speed, is expected to continue through Saturday. On the forecast track, the center of Florence will move over the southwestern Atlantic Ocean between Bermuda and the Bahamas tonight, and approach the coast of North Carolina or South Carolina in the hurricane warning area on Thursday and Friday, and move slowly near the coastline through Saturday. Maximum sustained winds have decreased to near 120 mph (195 km/h) with higher gusts. Florence is a category 3 hurricane on the Saffir-Simpson Hurricane Wind Scale. Some fluctuations in strength will be possible through Thursday morning. Although slow weakening is expected to begin by late Thursday, Florence is forecast to be an extremely dangerous major hurricane when it nears the U.S. coast late Thursday and Friday. Hurricane-force winds extend outward up to 70 miles (110 km) from the center and tropical-storm-force winds now extend outward up to 195 miles (315 km). The estimated minimum central pressure is 949 mb (28.03 inches). HAZARDS AFFECTING LAND ---------------------- STORM SURGE: The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. The water has the potential to reach the following heights above ground if peak surge occurs at the time of high tide... Cape Fear NC to Cape Lookout NC, including the Neuse, Pamlico, Pungo, and Bay Rivers...9-13 ft North Myrtle Beach SC to Cape Fear NC...6-9 ft Cape Lookout NC to Ocracoke Inlet NC...6-9 ft South Santee River SC to North Myrtle Beach SC...4-6 ft Ocracoke Inlet NC to Salvo NC...4-6 ft Salvo NC to North Carolina/Virginia Border...2-4 ft Edisto Beach SC to South Santee River SC...2-4 ft The deepest water will occur along the immediate coast in areas of onshore winds, where the surge will be accompanied by large and destructive waves. Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances. For information specific to your area, please see products issued by your local National Weather Service forecast office. RAINFALL: Florence is expected to produce heavy and excessive rainfall in the following areas... Coastal North Carolina...20 to 30 inches, isolated 40 inches. This rainfall would produce catastrophic flash flooding and significant river flooding. South Carolina, western and northern North Carolina...5 to 10 inches, isolated 20 inches. Elsewhere in the Appalachians and Mid-Atlantic states...3 to 6 inches, isolated 12 inches. WIND: Hurricane conditions are expected to reach the coast within the hurricane warning area late Thursday or Friday. Winds are expected to first reach tropical storm strength on Thursday, making outside preparations difficult or dangerous. Preparations to protect life and property should be rushed to completion. TORNADOES: A few tornadoes are possible in eastern North Carolina beginning late Thursday morning. SURF: Swells generated by Florence are affecting Bermuda, portions of the U.S. East Coast, and the northwestern and central Bahamas. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office.
Hurricane Florence Discussion Number 54 NWS National Hurricane Center Miami FL AL062018 500 PM EDT Wed Sep 12 2018 Data from an Air Force Reserve hurricane hunter aircraft along with satellite imagery and various intensity estimates indicate that Florence has weakened instead of strengthening. However, while the hurricane hasn't strengthened in terms of peak winds, the inner-core and outer wind fields have continued to expand, resulting in an increase the cyclone's total energy, which will create a significant storm surge event. The upper-level outflow remains impressive and is still expanding except toward the south. Florence is moving toward the northwest or 315/14 kt. The new 12Z global and regional model runs have come into much better agreement on Florence moving steadily northwestward around a strong ridge located between Bermuda and the U.S. mid-Atlantic region for the next 48 hours or so. By late on day 2, Florence is forecast to approach the southern portion of the North Carolina coast, then slow down considerably and turn westward within collapsing steering flow, with a very slow westward motion near the coasts of North and South Carolina continuing into Friday and Saturday. Corrected-consensus models HCCA and FSSE remain very close to each other and are quite similar to the simple consensus model TVCA. Therefore, only a slight eastward shift was needed to the previous forecast track through 36 hours or so, mainly due to the more eastward initial position based on the reconnaissance fixes. At 48 hours and beyond, no significant changes were required to the previous advisory track, which still shows Florence moving slowly westward across South Carolina and western North Carolina on day 4, followed by a slow northward motion up the Appalachian mountain chain on day 5. A narrow window of opportunity remains during the next 24 hours or so for Florence to strengthen a little when the hurricane passes over the warmer SSTs and deeper warm water/higher upper-ocean heat content associated with the Gulf Stream, and low vertical shear conditions of 5-10 kt will aid in any strengthening process. However, significant strengthening is not anticipated due to Florence's large and expanding inner-core wind field. By 36 h and beyond, decreasing ocean heat content along with the slowing forward speed of Florence will likely produce cold upwelling beneath the hurricane, inducing a gradual weakening trend. When Florence moves over the shallow coastal shelf waters in 48-72 h, land interaction and more significant upwelling are anticipated, which should further enhance the weakening process. The NHC intensity forecast remains near the higher statistical guidance through 48 hours, then follows the trend of the decay SHIPS model after that time. Although the maximum winds are expected to weaken a little more, Florence is still expected to remain a dangerous major hurricane as it approaches the coast. The threat to life from storm surge and rainfall will not diminish, and these impacts will cover a large area regardless of exactly where the center of Florence moves. Key Messages: 1. A life-threatening storm surge is now highly likely along portions of the coastlines of South Carolina and North Carolina, and a Storm Surge Warning is in effect for a portion of this area. All interests in these areas should complete preparations and follow any advice given by local officials. 2. Life-threatening, catastrophic flash flooding and prolonged significant river flooding are likely over portions of the Carolinas and the southern and central Appalachians late this week into early next week, 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 Warning is in effect. Strong winds could also spread inland into portions of the Carolinas. 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 12/2100Z 30.9N 72.5W 105 KT 120 MPH 12H 13/0600Z 32.1N 74.1W 110 KT 125 MPH 24H 13/1800Z 33.4N 75.9W 110 KT 125 MPH 36H 14/0600Z 33.9N 77.1W 105 KT 120 MPH 48H 14/1800Z 34.0N 77.9W 100 KT 115 MPH...NEAR THE COAST 72H 15/1800Z 33.6N 79.2W 70 KT 80 MPH...NEAR THE COAST 96H 16/1800Z 34.0N 81.7W 30 KT 35 MPH...INLAND 120H 17/1800Z 35.6N 83.4W 20 KT 25 MPH...POST-TROP/INLAND