Major Hurricane Earl Advisory 32 North Carolina Threat Assessment Prepared at: 8 AM Thursday September 2, 2010 Hurricane and Tropical Storm Warnings in effect for the North Carolina Coast and Sounds. NWS Raleigh, NC 1
800 AM Earl Information Position: 30.1 N 74.8 W, 355 nm south-southeast southeast of Cape Hatteras, NC. Intensity: Winds near 145 mph (cat. 4).. Earl has strengthened slightly and will remain a Major Hurricane as it approaches NC tonight and early Friday morning. Movement: Initially north northwest (330 degrees) at 18 mph. Watches/Warnings: Hurricane Warning from Bogue Inlet to VA border Tropical Storm Warning from Cape Fear to Bogue Inlet Impacts: Track: Hurricane Earl forecast unchanged bringing the storm within 60 miles of Cape Hatteras, NC tonight into early Friday morning with winds of 120+ mph Wind & Seas: Based on the current forecast the greatest impacts will be seas up to 20-25 feet along the Outer Banks with ocean over wash. Storm surge of 3 to 6 feet along the Outer Banks, southern Pamlico Sound and lower Neuse River. A breach of the Outer Banks near Hatteras is possible. 2
Hurricane Earl Analysis and Forecast Model Forecast Tracks as of 5am Thursday Model (left image) continue to cluster offshore the Outer Banks with just a few moving very close to the Outer Banks. Shear and drier around the storm will make intensity forecasts difficult through 36 hours, however, due to very warm waters the storm is forecast to remain a major hurricane as it approaches NC.
Wind Speed Probabilities Tropical Storm Force Winds are expected along the Outer Banks starting Tonight evening (90-100% chance). Tropical Storm Force Wind 50-60% chance along Highway 17 and a 25% chance as far inland as Interstate 95 and the Triangle early Friday morning. Damaging 58 mph wind expected along the Outer Banks and Pamlico Sound (70-80%) chance by 12 am Friday. 58 mph Wind 30% chance of damaging winds reaching Highway 17. Hurricane Force Wind Hurricane Force winds are most likely along the coast of NC (40-50% chance) across the Outer Banks by 12 am Friday. This will depend highly on the exact storm track and intensity which will change over time. 4
Forecast Winds Forecast wind gusts (kt) Tonight into Early Fri Forecast wind speeds based on the current track 65 75 mph gusts along the Outer Banks and Sounds starting around 12 AM Fri. 40 55 mph wind gusts along Highway 17 (higher on the water near New Bern and Washington) 30 35 mph gusts inland to near Interstate 95. Wind forecasts could change with later forecasts.
Coastal Impacts (from Newport/Morehead City NWS) Based on the current track, seas up to 25 feet (see image) are forecast in the coastal waters. Even if the track remains offshore, breakers on the Outer Banks will be up to 15 ft. Over wash issues are likely on the Outer banks ocean side tonight night just after midnight, peaking between midnight and 6 AM Friday. High tide will be around 230 AM. Forecast Wave Height 12 AM Fri A breach of the Outer Banks will be possible due to the combination of damaging surf and high winds.
Storm Surge Forecast Storm Surge Probability of surge greater than 5 feet 3-6 feet of storm surge expected along the Outer Banks as well as in the lower Pamlico Sound from Cape Hatteras to Ocracoke and Cedar Island to the lower Neuse River (above image) Locations/probabilities of storm surge greater than 5 to 6 feet (above image) are along the Outer Banks, Ocracoke and southern Pamlico Sound (above image)
Forecast Rainfall Rainfall Thursday afternoon into Friday Heaviest rainfall along the Outer Banks (3 5 inches with up to 6 inches possible) Rapid decrease in rainfall amounts west of Highway 17 where an inch or less of rain is forecast. Any flooding from heavy rain should be limited to coastal and sound counties. Rainfall forecasts could change with later forecasts.
Threat Summary Major Hurricane Earl continues to move towards NC passing within 60 miles of Cape Hatteras shortly after 12 AM Friday. Hurricane force winds expected along the Outer Banks with tropical storm force winds as far west as Highway 17. Storm surge of 3 6 feet in combination with waves of 15 feet from the ocean will create significant over wash of Highway 12 and beach erosion. Sound side surge of 3 6 feet will cause flooding from Cape Hatteras to Ocracoke and Cedar Island. Should the storm track closer to the coast storm surge values would be greater. Heaviest rainfall, up to 2 to 4 inches, should primarily remain over the Outer Banks and Sound counties. The official forecast track of Hurricane Earl along with most models turn the storm north on Thursday barely missing NC. This turn will be critical and a slower northward of the major hurricane would have huge impacts on NC. Everyone with interests over the eastern half of NC should be preparing now for Hurricane Earl and monitoring the latest forecasts from the National Hurricane Center. 9
References National Weather Service Raleigh, NC Jeff Orrock Warning Coordination Meteorologist jeff.orrock@noaa.gov (919) 515-8209 ext. 223 For the latest information please see the following websites: National Hurricane Center: http://www.nhc.noaa.gov/ NWS Raleigh Briefings: http://www.erh.noaa.gov/rah/downloads/briefings/ NWS Morehead City Briefings: http://www.erh.noaa.gov/mhx/downloads/briefings/ NWS Wilmington Briefings: http://www.erh.noaa.gov/ilm/downloads/briefings/ NWS Webpages: NWS Raleigh: http://www.erh.noaa.gov/rah/ NWS Wakefield: http://www.erh.noaa.gov/akq/ NWS Morehead City: http://www.erh.noaa.gov/mhx/ NWS Wilmington: http://www.erh.noaa.gov/ilm/