This is a developing story and will be updated.
After quickly intensifying this week, Hurricane Florence weakened slightly and was downgraded to a Category 2 storm on Wednesday before making landfall early Friday morning. As it neared the coast, the storm’s forward motion slowed to a crawl, but the winds and rain will continued at full-strength.
[ Hurricane Florence makes landfall in North Carolina, slamming state with ‘life-threatening’ rainfall ]
A hurricane can cause different types of damage when it makes landfall. Along the coast, storm surges and strong winds are the main concern. As the hurricane moves inland, it could lead to severe flooding from heavy rainfall, especially if it slows or stalls along its path.
Florence began on Aug. 30 as a disturbance in the eastern Atlantic and grew into a hurricane for the first time on Sept. 4. It varied in strength as it traveled west, at one point reverting to a tropical storm. But on Sept. 9, energized by warm Atlantic waters, Florence again became a dangerous hurricane.
Source: NOAA GOES-East imagery via AWS Earth. Flashes of yellow occur as sunlight interferes with the GOES satellite's sensors.
Life-threatening storm surge is expected along the coast

Potential storm surge flooding
6
1 ft.
3
9 ft. or more
Atlantic
Ocean
Norfolk
—Nags Head
VA.
NORTH
NORTH
CAROLINA
2 a.m.
Friday
Wilmington—
2 a.m.
Saturday
Myrtle Beach—
2 a.m.
Sunday
—Charleston
SOUTH
CAROLINA
—Savannah
GA.

Potential storm surge flooding
6 feet
1 foot
3 feet
9 feet or more
VA.
Raleigh
Norfolk
Columbia
Augusta
NORTH CAROLINA
SOUTH CAROLINA
GA.
2 a.m. Sunday
Myrtle
Beach
Wilmington
Charleston
Savannah
2 a.m.
Saturday
2 a.m. Friday
50 MILES

Potential storm surge flooding
6 feet
1 foot
3 feet
9 feet or more
VA.
Raleigh
Norfolk
NORTH CAROLINA
Columbia
Augusta
Fayetteville
Greeneville
SOUTH CAROLINA
GEORGIA
—Nags Head
2 a.m. Sunday
Myrtle
Beach
Pamlico Sound
Hatteras
Wilmington
Charleston
Savannah
2 a.m. Saturday
2 a.m. Friday
50 MILES

Land
Hurricane
eye
Rotation
direction
Water
Diagram is schematic

Land
Hurricane
eye
Rotation
direction
Water
Diagram is schematic
Along the coastline where Florence makes landfall, a maximum storm surge of 15 to 20 feet is possible. Storm surges are abnormal rises in sea level generated by intense storms. Surges generally occur on the side of the storm where winds rotate into the shore. The strongest surges are where the winds are most powerful, usually near the storm’s eye.

Hurricane
Wind-driven storm surge
Land
Normal sea level

Wind-driven storm surge
Hurricane
Land
Normal sea level

Wind-driven storm surge
Hurricane
Land
Normal sea level
Water is pushed toward land by strong wind and, to a lesser extent, by low pressure around the storm. The height of a storm surge can be affected by many factors, such as the size and speed of the storm, the angle of its approach, the shape of the coastline and the slope of the continental shelf.
Rainfall could bring dangerous inland flooding

7-day projected
precipitation
1 inch
20
VA.
Norfolk
TN.
N.C.
Raleigh
Sunday
Sat.
8 a.m.
Friday
Columbia
S.C.
Wilmington
GA.
Charleston
Myrtle Beach
Savannah
100 MILES
As of 11:00 a.m. Sept. 13
8 a.m.
Friday

VIRGINIA
Norfolk
TENN.
NORTH
CAROLINA
Raleigh
Charlotte
Fayetteville
SOUTH
CAROLINA
Florence
8 a.m. Sunday
8 a.m. Friday
Wilmington
Atlanta
Columbia
8 a.m.
Saturday
Myrtle
Beach
Augusta
Charleston
GEORGIA
7-day projected precipitation
60 MILES
1
inch
20
inches
Savannah
As of 11:00 a.m. Sept. 13

Virginia
VIRGINIA
Beach
TENN.
NORTH
CAROLINA
Raleigh
Charlotte
Fayetteville
SOUTH
CAROLINA
Florence
8 a.m. Sunday
8 a.m. Friday
Wilmington
Atlanta
Columbia
8 a.m. Saturday
Myrtle Beach
Augusta
GEORGIA
Charleston
7-day projected precipitation
50 MILES
1
inch
20
inches
Savannah
As of 11:00 a.m. Sept. 13
Warm ocean temperatures fueled Florence this week
Abnormally warm water temperatures in the western Atlantic helped strengthen the storm as it churned across the ocean. Temperatures above 27.8 degrees Celsius — or 82 degrees Fahrenheit — are ideal for the formation of tropical storms. As the storm churns the water and dumps tons of cold rain, it leaves much cooler ocean surfaces behind.

Sea surface temperature anomaly
4°C
cooler
than normal
4°C
warmer
than normal
normal
As of Sept. 12
As Florence passed, churning the waters and dumping rain into the ocean, sea surface temperatures decreased.
Unusually warm waters in the western Atlantic helped fuel the rapid strengthening of the storm.
Waters in this area are warmer than 27.8°C (82°F), which is ideal for hurricane formation.

Sea surface temperature anomaly
4°C cooler
than normal
4°C warmer
than normal
normal
VA
N.C.
S.C.
Wilmington
GA
Waters in this area are warmer than 27.8°C (82°F), which is ideal for hurricane formation.
As Florence passed, churning the waters and dumping rain into the ocean, sea surface temperatures decreased.
FL
Unusually warm waters in the western Atlantic helped fuel the rapid strengthening of the storm.
As of Sept. 12

Sea surface temperature anomaly
4°C cooler
than normal
4°C warmer
than normal
normal
VA
N.C.
S.C.
Wilmington
GA
Waters in this area are warmer than 27.8°C (82°F), which is ideal for hurricane formation.
FL
As Florence passed, churning the waters and dumping rain into the ocean, sea surface temperatures decreased.
Unusually warm waters in the western Atlantic helped fuel the rapid strengthening of the storm.
As of Sept. 12
About this story
Storm path data from the National Oceanic and Atmospheric Administration. Historic precipitation data from NOAA’s Advanced Hydrologic Prediction Service. Precipitation projections from National Weather Service Prediction Center. Potential surge surge flooding from National Hurricane Center. Sea surface temperature anomaly data from NOAA’s Coral Reef Watch.
Originally published Sept. 7, 2018.
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