Florence Now a Category 4 Hurricane and Still Strengthening

Sep 10, 2018

Florence rapidly intensified into a "potentially catastrophic" Category 4 storm Monday morning, the National Hurricane Center said in a special statement at 12 pm. This was based on data from a NOAA Hurricane Hunter aircraft's most recent pass through the eye, which found maximum sustained winds near 130 mph and a central pressure of 946 mb. The storm was located 925 miles south-southeast of Bermuda, or 1230 miles southeast of Cape Fear, North Carolina, and moving west at 13 mph. mph.

Major Hurricane Florence will likely threaten portions of the North and South Carolina coast with life-threatening surge, extreme wind, and flooding rains on Thursday. Hurricane Florence is then likely to slow down or even stall across the Piedmont this weekend, putting millions at risk for extreme flooding from South Carolina to Virginia. 

GOES 16 satellite image of Hurricane Florence as it continued to intensify Monday, courtesy of NOAA.

Hurricane Florence strengthened from a Category 1 to a Category 3 storm in less than 12 hours, which is rare but explicitly forecast by the National Hurricane Center (NHC) Sunday. The presence of warm ocean temperatures and relatively light winds aloft created an environment favorable for such intensification. Conditions near Florence are expected to remain favorable for additional strengthening through Wednesday, when the season's first major hurricane is likely to become a Category 4 storm.
 

Official advisory and track forecast from the National Hurricane Center on Hurricane Florence as of midday Monday.

As Florence approaches land, the hurricane's wind field is expected to grow in geographic size with time, increasing the risks for storm surge and inland wind threats. The Storm Surge unit from the National Hurricane Center advised on Twitter they would likely issue a Storm Surge Watch for portions of the South Carolina coast by Tuesday morning.

In his key messages Monday, NHC Hurricane Specialist Eric Blake said fluctuations in intensity are possible as the storm approaches land due to eye wall replacement cycles, but regardless of its exact intensity, he had “increasing confidence” that Florence will be a large and dangerous hurricane at landfall. The average track error from the National Hurricane Center four days out is about 140 nautical miles, and the dangerous hazards from Florence will extend well away from the center.

Forecast confidence is higher than normal with Florence through Wednesday, lending credence to the idea it will be approaching the coast of North or South Carolina by Wednesday night. However, specifics on where and when it might come ashore, where it might go next, or if it stalls are too difficult to pin down at this time. A fleet of aircraft from NOAA and the U.S. Air Force Reserves have been surveying the storm's lower and upper-level conditions, providing valuable data that will be considered in future forecasts.