Official Discussion issued by the National Hurricane Center

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

Copy of official data

Hurricane Florence Discussion Number  60
NWS National Hurricane Center Miami FL       AL062018
500 AM EDT Fri Sep 14 2018

An Air Force Hurricane Hunter aircraft has been investigating
Florence over the past few hours.  Data from the aircraft indicate
little change in the intensity with the central pressure holding
fairly steady.  The current intensity estimate is kept at 80 kt for
this advisory.  There were a couple of SFMR-observed surface winds
that were a little higher than that value, however these
observations were very near Cape Lookout North Carolina, where
shoaling likely caused some inflated wind speeds.  The current
intensity estimate is also consistent with peak WSR-88D Doppler
radar velocities.  The center of Florence will be moving inland very
soon, but is expected to slow down even more today and tonight.  As
a result, it will remain fairly close to the coast today, with much
of the circulation still over water. Therefore only a gradual
decrease in intensity is called for through tonight. Over the
weekend, a faster rate of weakening is likely while the center moves
at a faster pace and goes farther inland.

The hurricane is turning westward as it continues a slow forward
motion of about 285/5 kt.  Florence is currently in a region of weak
steering currents associated with a col between two mid-level
anticyclones.  Over the next few days, a high pressure area is
forecast to build to the east-northeast of the tropical cyclone.
As a result, the system should gradually turn northwestward and
northward in 2-3 days.  Later in the forecast period, Florence
should turn northeastward as it approaches the mid-latitude
westerlies.  The official track forecast is similar to the
previous one and about in the middle of the dynamical guidance
suite.

It cannot be emphasized enough that the most serious hazard
associated with slow-moving Florence is extremely heavy rainfall,
which will cause disastrous flooding that will be spreading 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  14/0900Z 34.2N  77.4W   80 KT  90 MPH
12H  14/1800Z 34.1N  78.3W   75 KT  85 MPH...INLAND
24H  15/0600Z 33.9N  79.1W   65 KT  75 MPH...INLAND
36H  15/1800Z 33.8N  79.9W   45 KT  50 MPH...INLAND
48H  16/0600Z 34.1N  81.1W   35 KT  40 MPH...INLAND
72H  17/0600Z 36.6N  83.2W   25 KT  30 MPH...INLAND
96H  18/0600Z 40.5N  80.5W   25 KT  30 MPH...POST-TROP/INLAND
120H  19/0600Z 43.5N  72.0W   25 KT  30 MPH...POST-TROP/INLAND

$$
Forecaster Pasch