SECTION 4: RISK ASSESSMENT
lanes of Capital Boulevard near the intersection of Brentwood Road. The softball field and walking trail in Brentwood Park also experienced flooding, with 4 to 5 feet of flowing water through the park. September 6, 2008 – During the early morning house Tropical Storm Hanna made landfall near Myrtle beach, SC and tracked north into central North Carolina along Interstate 95. Four to seven inches of rain which fell over the eastern piedmont resulted in flash flooding over large areas including the Triangle. Up to seven inches of rain caused flash flooding in many locations across Raleigh particularly along Crabtree Creek and other flood prone areas. A motorist was rescued from a vehicle after driving into a flooded underpass at Hillsborough Drive and Chapel Hill Drive in west Raleigh. Sullivan Drive between Dan Allen and Varsity Drive was closed due to flooding along with Avent Ferry Road at Trailwood Drive. Number creeks across the region flooded low lying areas as well as some vehicles. May 5, 2009 - Two tornadic supercells developed along a stalled warm front that extended across southern piedmont and coastal plain of North Carolina. The cells produced 4 tornadoes in Johnston, Nash and Wilson counties. July 17, 2016 - A warm moist atmosphere combined with a disturbance moving across central North Carolina during peak heating, modest instability and seasonably strong deep layer shear allowed for the development of numerous showers and storms during the late afternoon into the evening. Many of these storms became strong to severe and produced widespread wind damage. In addition, several areas of very heavy rain fell across the Northern Coastal Plain and the Triangle Region of central North Carolina. This resulted in many reports of flooding and water rescues. September 17, 2018 - A ridge of high pressure over eastern North America stalled Florence's forward motion a few miles off the southeast North Carolina coast on September 13th. Hurricane Florence made landfall near Wrightsville Beach early on Saturday September 15, and weakened further as it moved slowly inland. Despite making landfall as a weakened Category 1 hurricane, Florence still produced 40 to 70 mph wind gusts, enough wind speed to uproot trees and cause widespread power outages throughout the Carolinas. As the storm moved inland, from September 15 to 17, heavy rain of 10 to 25 inches caused widespread inland flooding, inundating cities such as Fayetteville, Smithfield, Goldsboro, Durham, and Chapel Hill, and causing major river flooding on main-stem rivers such as the Neuse, Cape Fear, and Little River. Most major roads and highways in the area experienced some flooding, with large stretches of I-40 and I-95 remaining impassable for days after the storm had passed. The storm also spawned tornadoes in several places along its path. August 11, 2022 - A cluster of showers and thunderstorms developed along a slow moving cold front across the central Piedmont of central North Carolina. A few of the storms became strong to severe and produced damaging wind gusts and flash flooding across Wake County. PROBABILITY OF FUTURE OCCURRENCE By definition of the 100-year flood event, SFHAs are defined as those areas that will be inundated by the flood event having a 1-percent chance of being equaled or exceeded in any given year. Properties located in these areas have a 26 percent chance of flooding over the life of a 30-year mortgage. The 500-year flood area is defined as those areas that will be inundated by the flood event having a 0.2- percent chance of being equaled or exceeded in any given year; it is not the flood that will occur once every 500 years. While exposure to flood hazards vary across jurisdictions, all jurisdictions have at least some area of land in FEMA flood hazard areas, therefore the likelihood of flooding is considered possible (between 10% and 50% annual probability) for all jurisdictions. Additional flood risk comes from localized stormwater flooding and flash floods. Historical records indicate that an average of 11.68% flood or flash flood events occur each year in the planning area.
Wake County, NC Multi-Jurisdictional Hazard Mitigation Plan
WSP June 2024 Page 137
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