Tropical Storm Ana Threat Assessment for northeast South Carolina & southeast North Carolina Created 615 AM Sat May 9, 2015 Reid Hawkins, Science Officer National Weather Service Wilmington, NC 1
New Information Ana has now been classified as a tropical storm. Ana is now believed to have reached its maximum intensity. As it moves closer to the coast it will move over cooler shelf water and slowly weaken as it move onshore. Tropical Storm Warnings are in effect for Pender, New Hanover, Brunswick, Horry and Georgetown Counties and the coastal waters from the South Santee River northward to Surf City. The warning has been extended farther north with the latest advisory. The latest forecast track has changed very little from the previous advisory with a landfall between Myrtle Beach and Wilmington. 515 AM Sat May 9, 2015 2
Expected Threats/Impacts Matrix Hazards Specific to southeast NC and northeast SC Given the slow progression of this storm the inland flooding hazard may be increased, especially across coastal portions of northeast SC and coastal southeast NC. An isolated tornado risk will persist as well, and the winds will be highest along the coastal areas. 3
Wind Threats/Impacts - Summary Overview Tropical Storm Ana will bring winds near tropical force by Saturday Afternoon with winds 30 to 35 mph and gust up to 50 mph along the beaches of the coastal counties. Gusty winds will persist into Saturday night and Sunday given the slow progression of the storm. Power Outages Isolated power outages possible, especially along coastal areas. Tree Damage Some limbs and weak trees near the coast may be blown down. Structural Damage Only minor damage is expected, especially along the coast. Tropical Storm Force Wind Speed Probabilities Per the graphic (left) locations from Georgetown to near Wrightsville Beach have about the same chance of receiving tropical storm force winds. 4
Potential Rainfall Amounts -Forecast continue to show the storm total rainfall amounts of 1 to 3 inches with the highest amounts across coastal Cape Fear. -Isolated higher amounts are possible. Note that there are much higher rainfall amounts expected just off the coast. Thus any deviation in the track could bring higher amounts back across coastal Cape Fear and northeast SC. Storm total values today through 8 AM Tuesday 5
Tornado Risk Valid Saturday Valid Sunday **Chance for isolated tornadoes has lessen for today from previous forecast and slightly better chance on Sunday. 6
Marine, Surf, Aviation, and River Threats/Impacts Winds/Seas Across the Coastal Waters (0 to 20 nm) winds will increase to 30 to 35 knots with higher gusts through Sunday Night. Seas will build in excess of 10 ft. Conditions farther offshore, especially in the vicinity of the Gulf Stream will be much worse today. Inlet entrances are expected to become hazardous as well, especially during the falling tide. The large incoming waves and currents in the inlet will generate large/steep waves. Rip Currents & Surf Strong rip currents, large breakers, and strong longshore currents will create dangerous surf conditions at all local beaches. MVFR Ceiling are expected through the storm and IFR visibilities are possible during squalls as the rain bands move through. Strong NE to E winds will impact operations through Sunday. With expected rainfall amounts of less than 5 inches at this time all Rivers are expected to remain in their banks. Note: if the axis of heavier rain is able to push onto the coast then rivers along coastal areas will need to be closely monitored. 7
Storm Information Advisory #6 5 AM EDT Sat May 9 Position: 32.4 N / 77.6 W, 120 miles southeast of Myrtle Beach, SC, or about 130 miles south of Wilmington, NC. Intensity: Sustained winds are near 60 mph. Little additional strengthening is expect. Movement: Ana is slowly moving to the north-northwest at 3 mph with a slow increase in speed and turn the northwest and then north later today and overnight. Minimum Pressure: 998 mb or 29.47 inches. 8
Official Track Information The latest track shows a slow increase in speed to the northwest today with a turn to the north on Sunday. The storm is expect to come onshore between Myrtle Beach and Wilmington overnight. The first tropical force winds are expected to arrive at coastal areas Saturday afternoon and continue into Sunday. A few gusts to tropical storm force are possible farther inland with any rain bands. NHC Advisory # 6 5 AM EDT Sat May 9, 2015 *Note: This graphic does not represent an impact swath, and also note that statistically, one third of the time the storm can be outside the 5 day error cone. 9
Additional Information Available at: Facebook: US National Weather Service Wilmington NC Twitter: @NWSWilmingtonNC Web: http://weather.gov/ilm National Weather Service Wilmington, NC 10