Hurricane Matthew Threat Assessment for northeast South Carolina & southeast North Carolina National Weather Service Wilmington NC 730 AM EDT Tuesday October 4, 2016 Steven Pfaff, WCM Steven.Pfaff@noaa.gov Weather Forecast Office Wilmington, NC weather.gov/ilm @NWSWilmingtonNC 1
New Information Included a slide for the initial look at impacts and confidence levels. The track was nudged westward from yesterday. The threat continues to increase along the Carolina Coast. All persons in southeast NC and northeast SC should take preliminary actions starting today to prepare for potential impacts from Hurricane Matthew s approach at the end of the week. 2
Impact Initial Look at Potential Impacts and Confidence Wind Surge Flooding Tornado Marine/ Coastal Extreme High Moderate Elevated Confidence Limited Limited Limited Low Very Confident 3
Potential Impacts **Specific details on impacts are difficult to determine at this time given the uncertainty in the track, however, given the latest advisory a possibility exists for high impacts. Impacts would begin Fri and persist into Sat before improving Sun. Marine/Coastal Extreme impacts are possible with very large waves, dangerous boating/shipping and surf conditions, and the potential for significant erosion. Inlet entrances will be especially hazardous as well. Wind A direct, or near hit, would bring high wind impacts to the area with the potential for some structural and roof damage, downed trees and power lines with widespread/lengthy power outages. Wind impacts would be less if the storm tracks farther off the coast. Surge A direct, or near hit, would bring high surge impacts to the area with the potential for storm surge inundation accentuated by large battering waves. Any inundation would impact vulnerable low-lying homes along the coast. Sections of coastal roads could become flooded & aids to navigation may become off station or missing. Flooding Many areas are saturated from recent heavy rainfall. Additional heavy rainfall would lead to flash flooding. Some rivers and streams may rapidly overflow their banks. Many roads may become flooded as well, with the potential for road failures. The delivery of drinking water and sewer services may be impacted. Tornado The occurrence of a few tornadoes can affect preparedness actions during tropical events. They can cause structural damage, trees to snap or become uprooted, power outages, and communications failures. 4
Tropical Storm and Hurricane Wind Probabilities The probability for Tropical Storm Winds continues to increase across southeast NC and northeast SC. Hurricane Force Wind Speed Probabilities continue as well, but are expected to increase once the storm moves into the Bahamas. These graphics are for a 120 hour period from 2 AM EDT Tuesday Oct 4 th to 2 AM EDT Sunday Oct 9 th. 5
Official NHC 5 Day Forecast Track The official track has shifted slightly to the west, placing the area well within the 5 Day forecast cone. Hurricane Matthew may move by as a strong to possibly major hurricane. With the closest approach during Saturday. Do not focus on the exact track of Matthew as it will shift overtime. Note, this is not an impact cone. Advisory #25 5 AM EDT Tue Oct 4, 2016 Position: 17.8N / 74.4W (35 Mi. S of Tiburon Haiti) Movement: Toward the North at 9 mph Intensity: 145 MPH (Category 4) Min. Pressure: 934 MB or 27.58 inches 5 AM NHC Advisory #25 Tuesday Oct 4, 2016 Hurricane Matthew 5 Day Forecast Cone *Note: statistically, one third of the time the storm can be outside of the 5 day error cone 6
Model Information Some uncertainty remains, but overall there is general agreement within the models bringing Matthew to, or near, the Carolina coast at the end of the week. Note: tropical cyclones can, and do, deviate from the model consensus. As a result, please refer to the official advisory from the National Hurricane Center. 7
Key Points The risk for receiving direct impacts from Hurricane Matthew continues to increase for the Carolinas. It is plausible that high wind, surge, and flood impacts could occur at the end of the week as Matthew makes its closest approach to the area. Impacts would be greatest on Saturday given the current forecast. Marine/Coastal impacts are expected to be extreme with dangerous surf, steep waves, significant beach erosion, and strong rip currents. All residents should begin taking initial preparation steps today. Be ready to ramp-up your preparation efforts in coming days. NEXT PDF BRIEFING: 8 AM EDT - Tuesday October 4, 2016 8