Hurricane Isaias: August 3-4, 2020

Hurricane Isaias (pronunciation: ees-ah-EE-ahs) was a category one hurricane that made landfall at Ocean Isle Beach, NC during the evening of August 3, 2020 with maximum sustained winds near 85 mph.  The storm's rapid movement limited rainfall amounts, however significant storm surge flooding and multiple tornado touchdowns occurred across portions of coastal South and North Carolina.

Storm History

A tropical wave moved off the coast of Africa on July 23 and traveled westward across the tropical Atlantic Ocean. It entered the Caribbean Sea on July 29 as a Potential Tropical Cyclone with winds as high as 45 mph.  The system gradually became better organized, and Tropical Storm Isaias was born south of Puerto Rico at 11 p.m. on July 29.  Turning northwestward, Isaias made its first landfall on the Dominican Republic early on July 30, then strengthened to a category one hurricane while moving across the southern Bahamas on July 31.

Dry air, increasing wind shear, and passage of the hurricane's center over Andros Island in the Bahamas weakened Isaias back to a tropical storm on August 1.  Turning north on August 2, Tropical Storm Isaias encountered the warm Gulf Stream water off the Florida, Georgia and South Carolina coastline. However persistent wind shear prevented the storm from strengthening significantly.

Wind shear weakened slightly during the evening of August 3. Isaias took advantage of the more favorable conditions as it approached land and once again became a category one hurricane.  Hurricane Isaias made landfall at Ocean Isle Beach, North Carolina just after 11 pm on August 3 with maximum sustained winds near 85 mph.

Color-enhanced Infrared satellite loop showing Hurricane Isaias making landfall and moving inland across eastern North Carolina. August 3-4, 2020

Storm Surge

A damaging storm surge occurred along the Horry County coastline during the evening high tide on August 3.  The middle portion of the Sea Cabin Pier at Cherry Grove was destroyed. Homes in low lying areas near the beach were flooded and dune erosion was severe.  Main Street between Ocean Blvd and Hillside Drive was closed due to flooding.  Sea Mountain Highway (SC Highway 9) was covered with 12 to 18 inches of water up to four blocks in from the beach.  In North Myrtle Beach water up to one foot deep reached about a block inland.  Ocean Blvd in Myrtle Beach was closed due to flooding for a time, and in Garden City North Waccamaw Drive was flooded and closed during high tide.

Damaging storm surge flooding continued northward along the south-facing coastline of Brunswick County including Holden Beach, Ocean Isle Beach, Oak Island, and Southport.  In Southport, extensive damage occurred to a hundred or more boats moored at the town's marina.  Approximately twenty small and medium sized boats were shown in news photos to have been pushed across the Cottage Creek marsh and came to rest at the Indigo Plantation neighborhood.  Up to three feet of storm surge flooding caused heavy damage to waterfront shops in Southport.  Bulkheads were eroded along East Bay Street and a portion of the sidewalk collapsed.  On Oak Island storm surge flooding damaged or destroyed an estimated 75-100 vehicles.  Sand dunes were washed onto streets up to three blocks inland.  On Holden Beach 42 of the 45 sea turtle nests identified before the storm were destroyed.  Town officials estimated damage around $40 million.  At Ocean Isle Beach and Caswell Beach significant beach erosion occurred and sand dunes were destroyed. 

The storm surge moved up the tidal portion of the Cape Fear River into downtown Wilmington, causing significant street flooding and damaging some first-floor businesses along Water Street.  The downtown river gauge reached its highest level in history at 9.03 feet MLLW, eclipsing the previous record of 8.28 feet set just two years earlier during Hurricane Florence.

Winds

Gusts over hurricane force occurred at a number of weather stations along the North Carolina coast. These winds caused damage to trees, power lines, and some structures.

The highest wind gusts occurred at the beaches near and east of the landfall point across Brunswick, New Hanover, and Pender counties in southeastern North Carolina.The Fort Anderson State Historic Site in Brunswick County, NC said just as many trees were lost in Isaias as were lost in Hurricane Florence two years earlier.  Brunswick County reported 53,000 customers without power at the height of the storm.  Across New Hanover county downed trees and power lines knocked out electrical service to 85,000 residents.  A few business signs were blown down, and most traffic lights were out of service during and immediately after the storm.  Pender County, NC officials reported 27,500 residents lost electrical power.  Damage to trees and power lines were mainly limited to the coastal sections of the county.

Tornadoes

Hurricane Isaias produced six confirmed tornado touchdowns across our portion of the Carolinas.  The strongest was an EF2 tornado that was on the ground for over eight miles from Bald Head Island to Southport around 8:00 pm on August 3.  Based on observed damage, this tornado likely had winds of 115 mph and a maximum path width of 70 yards.  A short-lived tornado at Garden City Beach at 8:20 pm on August 3 injured one person and damaged several homes. 

For more details on Hurricane Isaias' tornadoes, please see our GIS Storymap on Hurricane Isaias.

Radar loop of Hurricane Isaias making landfall, August 3-4, 2020

Rainfall Totals

After passing through the Carolinas, Tropical Storm Isaias continued to move north and impacted major cities in the Mid-Atlantic and Northeast including Norfolk, Philadelphia, and New York City.  Flooding due to heavy rainfall and strong wind gusts over 70 mph extended up the coast as far north as Long Island, NY.  Widespread power outages occurred, in some places for a week.

Additional Links of Interest

NWS Wilmington ArcGIS Storymap on Hurricane Isaias:  arcg.is/PPuO8

Wilmington Star-News gallery of Brunswick County, NC damage:  https://www.starnewsonline.com/photogallery/NC/20200804/PHOTOGALLERY/804009990/PH/1

USGS Flood Event Viewer:  https://stn.wim.usgs.gov/FEV/#2020HurricaneIsaias

USGS Field Crews Document Isaias' Effects Along Atlantic Coast:  https://www.usgs.gov/news/usgs-field-crews-document-isaias-effects-along-atlantic-coast

National Hurricane Center archive of Isaias advisories and forecasts:  https://www.nhc.noaa.gov/archive/2020/ISAIAS.shtml

National Weather Service Charleston, SC Isaias event summary:  https://www.weather.gov/chs/HurricaneIsaias-Aug2020

National Weather Service Newport/Morehead City, NC Isaias event summary:  https://www.weather.gov/mhx/HurricaneIsaias080420

Research & Page Author: Tim Armstrong
Last Updated: Oct 10, 2020