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

Parts of the Mid-Atlantic, especially from North Carolina’s northern regions to Pennsylvania, have already received 150 to 300 percent of their normal rainfall this summer. The National Weather Service has already warned that there will be heavy rain and flooding in these same regions.

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.

Share

Most Read

Follow Post Graphics