Hurricane Florence Track Chart, Advisory #49

Current Location: 26.8N, 65.2W
Geographic Reference: 910 miles ESE of Wilmington, NC
Movement: West-northwest at 19 mph
Max Winds: 125 mph gusting to 155 mph
Current Hurricane Severity Index: 32 out of a possible 50 points (19 size, 13 intensity)
Max Predicted Hurricane Severity Index: 36 out of a possible 50 points (16 size, 20 intensity)
Current Radius of Tropical Storm-Force Winds: 140 miles
Max Predicted Radius of Tropical Storm-Force Winds: 160 miles
Organizational Trend: Weakened overnight, but predicted to strengthen today
Forecast Confidence: Average

Key Points
1. We are indicating a slower movement and a westerly turn near landfall, which will increase the heavy rain threat and prolong the hurricane-force winds for coastal North Carolina.
2. A major inland flood event is expected for North Carolina, southern Virginia., and possibly northern South Carolina.

Our Forecast
A reconnaissance plane inside Florence has found that max sustained winds have decreased overnight. This is due to the current eyewall replacement cycle, in which a hurricane’s eyewall dissipates and a new larger eye forms. Hurricanes often weaken considerably during an eyewall replacement cycle. However, once the new eyewall fully forms and begins to contract, the winds will increase considerably, along with the core of stronger winds growing in size a little.

Model guidance has begun to come into better agreement on what will happen as Florence approaches the coast of North Carolina. We think that Florence’s forward speed will slow considerably on Thursday evening as the center nears the coast, followed by a turn to the west. This will increase the amount of time that hurricane-force winds will impact coastal areas, as the center may not move fully inland until Friday afternoon or possibly Saturday. The timing and sharpness of the westerly turn is uncertain. It is possible that the center may track westward across northern South Carolina on Saturday and Sunday.

The slowing and the westward turn will also mean that the threat of extremely heavy rainfall across central and eastern North Carolina would be increasing, resulting in widespread severe flooding, starting Thursday night and continuing into the following week. In addition, this could mean that hurricane-force winds lash the coast of North Carolina for 24 hours or more starting Thursday evening.

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. Major damage from inland flooding is also expected for central and eastern North Carolina.
Southern and SE Virginia : Major flood damage is likely for southern Virginia, with widespread street flooding likely for southeast Virginia. Coastal areas of Virginia will likely experience very high waves resulting in some coastal flooding.
DelMarVa Peninsula: Some flooding is possible for the Virginia portion of the Delmarva Peninsula.

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 on Wednesday into Thursday off the coast of South and North Carolina. Combined seas as high as 20 to 30 feet may occur off the coast of Virginia, Maryland, and Delaware Wednesday through Thursday.

Our next advisory will be issued by 4 PM EDT

Meteorologist: 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 Tue Sep 11 26.80N 65.20W 125 mph 155 mph Category 3 19 13 32
12 9PM CDT Tue Sep 11 28.00N 68.60W 145 mph 175 mph Category 4 18 17 35
24 9AM CDT Wed Sep 12 29.80N 71.20W 155 mph 185 mph Category 4 16 20 36
36 9PM CDT Wed Sep 12 31.50N 73.50W 155 mph 185 mph Category 4 14 20 34
48 9AM CDT Thu Sep 13 32.90N 75.30W 150 mph 180 mph Category 4 12 19 31
60 9PM CDT Thu Sep 13 33.90N 76.80W 140 mph 165 mph Category 4 12 16 28
72 9AM CDT Fri Sep 14 34.40N 77.80W 125 mph 155 mph Category 3 11 13 24
84 9PM CDT Fri Sep 14 34.60N 78.20W 80 mph 100 mph Category 1 4 5 9
96 9AM CDT Sat Sep 15 34.80N 78.70W 60 mph 70 mph Tropical Storm 2 3 5
108 9PM CDT Sat Sep 15 34.90N 79.30W 40 mph 45 mph Tropical Storm 1 1 2
120 9AM CDT Sun Sep 16 35.00N 80.10W 30 mph 35 mph Remnant Low 0 0 0
132 9PM CDT Sun Sep 16 35.00N 81.20W 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.