Official Discussion issued by the National Hurricane Center

Florence (AL062018) DATA RELEASED: 9/14/2018 3:00:00 PM UTC

Copy of official data

Hurricane Florence Discussion Number  61
NWS National Hurricane Center Miami FL       AL062018
1100 AM EDT Fri Sep 14 2018

Florence's satellite signature remains very impressive even though
the eye is now located just inland over southeastern North Carolina
near Cape Fear. However, land interaction has taken its toll on the
inner-core circulation, and the previously well-defined eye in
radar imagery has shrunk and become filled with rain echoes. The
advisory intensity has been lowered to 70 kt based on earlier
reports from an Air Force Reserve reconnaissance aircraft, NOAA
Doppler weather radar velocity data from Wilmington and Morehead
City, and nearby surface observations. The central pressure of 958
mb is based on observations from a NOAA NOS site in Wrightsville
Beach and a Weatherflow private station in Federal Point. Another
Air Force Hurricane Hunter aircraft will be sampling the portion of
Florence's circulation over water during the next few hours.

Florence has turned west-southwestward and the motion estimate
is now 245/03 kt. Florence is expected to remain embedded within a
weak steering flow regime within a weakness in the subtropical
ridge, resulting in a slow westward motion for the next 36-48 hours
across South Carolina. As a shortwave trough currently located over
the eastern Great Lakes to Maryland moves eastward away from the
region over the next 2 days, the ridge will begin to build back in
and shift eastward, allowing Florence or its remnants to gradually
turn northward over the weekend, and then move northeastward into
the mid-latitude westerlies as an extratropical low. The new NHC
forecast track is similar to the previous advisory, and is close to
the middle of the model guidance envelope.

Wind data from the earlier aircraft mission, along with Doppler
radar velocity data and surface observations, indicate that Florence
has weakened. Additional slow weakening is expected today as the
center of Florence moves farther inland, with more rapid weakening
forecast over the weekend as Florence moves westward across South
Carolina. The new NHC intensity forecast is a little lower than the
previous advisory, and closely follows the trend of Decay SHIPS
model.

Although coastal storm surge flooding will gradually subside later
today, it cannot be emphasized enough that another serious hazard
associated with slow-moving Florence is and will be extremely heavy
rainfall. More than 14 inches of rain has already fallen in many
areas across southeastern North Carolina, and more rain is still to
come, which will cause disastrous flooding that will spread inland
through the weekend.

Key Messages:

1. A life-threatening storm surge is already occurring along
portions of the North Carolina coast and will continue through
today and tonight.  This surge is also likely along portions of the
South Carolina coast.  The greatest storm surge inundation is
expected between Cape Fear and Cape Hatteras, including the Neuse
and Pamlico Rivers and western Pamlico Sound.

2. Life-threatening, catastrophic flash flooding and prolonged
significant river flooding are likely over portions of the Carolinas
and the southern and central Appalachians through early next week,
as Florence is expected to slow down while it moves inland.

3. Damaging hurricane-force winds are occurring along portions of
the North Carolina coast and are expected to spread to portions of
the South Carolina coast later today.  Strong winds could also
spread inland into portions of the Carolinas over the next
couple of days.

4. Large swells affecting Bermuda, portions of the U.S. East Coast,
and the northwestern and central Bahamas will continue this week,
resulting in life-threatening surf and rip currents.

FORECAST POSITIONS AND MAX WINDS

INIT  14/1500Z 34.0N  78.0W   70 KT  80 MPH...INLAND
12H  15/0000Z 33.9N  78.9W   65 KT  75 MPH...INLAND
24H  15/1200Z 33.8N  79.7W   55 KT  65 MPH...INLAND
36H  16/0000Z 33.9N  80.8W   35 KT  40 MPH...INLAND
48H  16/1200Z 34.7N  82.0W   25 KT  30 MPH...INLAND
72H  17/1200Z 37.7N  83.0W   25 KT  30 MPH...POST-TROP/INLAND
96H  18/1200Z 41.2N  78.4W   20 KT  25 MPH...POST-TROP/INLAND
120H  19/1200Z 44.4N  68.7W   20 KT  25 MPH...POST-TROP/INLAND

$$
Forecaster Stewart