Hurricane Florence Track Chart, Advisory #57

Current Location: 33.3N, 75.4W
Geographic Reference: 155 miles ESE of Wilmington, NC
Movement: West-northwest at 10 mph
Max Winds: 100 mph gusting to 115 mph
Current Hurricane Severity Index: 23 out of a possible 50 points (15 size, 8 intensity)
Max Predicted Hurricane Severity Index: 23 out of a possible 50 points (15 size, 8 intensity)
Current Radius of Tropical Storm-Force Winds: 180 miles
Max Predicted Radius of Tropical Storm-Force Winds: 180 miles
Organizational Trend: Weakening over the past 3-6 hours
Forecast Confidence: Average

Key Points
1. There are no significant changes to the track forecast, though we are indicating that Florence will be a little weaker at landfall.
2. Severe wind and tidal surge damage is expected for the southeast North Carolina Coast.
3. A catastrophic inland flood event is expected for North and South Carolina.

Our Forecast
A reconnaissance plane currently investigating Florence has found that its core has been disrupted overnight. Its eyewall is only partially intact in the southwest and northwest quadrants. As a result, Florence’s area of hurricane-force winds and 58 mph winds has increased, but the max sustained winds have decreased. The recon plane found max sustained winds of 85 mph in both the southwest and northeast quadrants in the past hour. In the last few minutes, the plane sampled the northwest quadrant, where it found that the max sustained winds were about 85 mph as well. However, the plane has not completed its investigation, so we are keeping its max winds at 100 mph in this advisory, which is likely a bit generous. While the lower wind may mean less destructive wind force on the coast as the center passes, the larger area of strong winds means that Florence will still produce a large and devastating storm surge as it moves into the North Carolina coast tonight.

We have not made any significant changes to the forecast track in this advisory. Florence is predicted to move ashore a little north of Wilmington early Friday morning. As Florence nears the coast, its forward speed will slow considerably, resulting in prolonged hurricane-force wind for coastal counties. By this time Friday morning, Florence should begin to accelerate to the west-southwest, moving into northeastern South Carolina tomorrow afternoon and then west and northwestward into northwest South Carolina as a remnant low pressure area by Sunday morning.

As Florence slowly pushes inland during the day tomorrow, the primary concern will shift from the surge and the wind to the torrential rainfall and dangerous flooding that is likely to occur due to the system’s slow forward motion. Portions of southeastern North Carolina and northeastern South Carolina are expected to receive 20-30 inches of rainfall. These totals would result in catastrophic flooding. As Florence pushes farther inland, the rains may become less intense. However, much of northern South Carolina and central North Carolina could receive at least 6 inches of rainfall with localized totals up to 12 inches. As moisture from Florence reaches the mountains of western North Carolina, it is possible that there could be a secondary maxima of totals over 12 inches along east facing slopes. If this occurs, landslides are possible along east facing slopes.

Expected Impacts on Land
North Carolina: Severe wind and tidal surge damage is expected along the coast. Significant tidal surge damage may occur for the southern Outer Banks, with less damage likely for the northern Outer Banks. Catastrophic damage from inland flooding is also possible for southeastern North Carolina.
South Carolina: Wind damage is likely, along with widespread power outages for the northern coast. Some surge damage may also occur. Severe flooding is also expected both on the coast and inland in northern South Carolina
Southern and SE Virginia : Occasional heavy rain will result in localized flooding and travel delays.
Georgia and Tennessee: The heaviest rainfall will remain well east of Georgia and Tennessee. However, localized flooding is possible in northeastern Georgia on Sunday.

Expected Impacts Offshore
Offshore Delaware to North Carolina: Combined seas as high as 35 feet to 45 feet may occur within 100 miles of the track of Florence. Combined seas as high as 20 to 30 feet may occur off the coast of Virginia, Maryland, and Delaware through Friday

We will issue an intermediate advisory by 1 PM EDT. Our next full advisory will be issued by 4 PM EDT

Meteorologists: Chris Hebert

Forecast Confidence:   Average Hurricane Severity Index
Fcst Hour Valid Lat. Lon. Max Sustained Winds Max Gusts Category Size Intensity Total
0 9AM CDT Thu Sep 13 33.30N 75.40W 100 mph 115 mph Category 2 15 8 23
6 3PM CDT Thu Sep 13 33.70N 76.30W 100 mph 115 mph Category 2 15 8 23
12 9PM CDT Thu Sep 13 34.10N 77.10W 100 mph 115 mph Category 2 15 8 23
18 3AM CDT Fri Sep 14 34.30N 77.80W 100 mph 115 mph Category 2 12 8 20
24 9AM CDT Fri Sep 14 34.30N 78.20W 85 mph 105 mph Category 1 7 6 13
30 3PM CDT Fri Sep 14 34.30N 78.70W 80 mph 100 mph Category 1 6 5 11
36 9PM CDT Fri Sep 14 34.20N 78.90W 75 mph 85 mph Category 1 5 5 10
42 3AM CDT Sat Sep 15 34.10N 79.60W 70 mph 85 mph Tropical Storm 4 4 8
48 9AM CDT Sat Sep 15 33.90N 80.10W 60 mph 70 mph Tropical Storm 2 3 5
54 3PM CDT Sat Sep 15 33.80N 80.70W 45 mph 60 mph Tropical Storm 1 2 3
60 9PM CDT Sat Sep 15 33.80N 81.20W 40 mph 50 mph Tropical Storm 1 1 2
72 9AM CDT Sun Sep 16 34.60N 82.60W 30 mph 40 mph Remnant Low 0 0 0
84 9PM CDT Sun Sep 16 35.70N 83.50W 30 mph 35 mph Remnant Low 0 0 0
96 9AM CDT Mon Sep 17 36.90N 83.10W 30 mph 35 mph Remnant Low 0 0 0

The yellow cone represents track error from the previous five hurricane seasons. Over the past five hurricane seasons, the center of the storm tracked within the yellow cone 75% of the time. The cone does not represent the forecast uncertainty in the current advisory for this storm. In addition, hurricane-force winds, very high tides, large waves, and heavy rainfall can often extend well outside the yellow cone.