564 
 WTNT41 KNHC 120853
 TCDAT1
 
 Hurricane Florence Discussion Number  52
 NWS National Hurricane Center Miami FL       AL062018
 500 AM EDT Wed Sep 12 2018
 
 The eye of Florence remains very distinct in infrared satellite
 imagery this morning.  There has been little change to the cloud top
 temperatures surrounding the eye overnight, however, the overall
 cloud shield and central dense overcast has become slightly more
 symmetric.  An Air Force Reserve Hurricane Hunter aircraft that was
 in the hurricane until just after midnight measured a peak 700-mb
 flight-level wind of 130 kt, and a SFMR wind of 107 kt in the
 northeast eyewall.  A blend of these data and recent subjective and
 objective satellite intensity estimates supports an initial wind
 speed of 115 kt.  Florence will be moving over sea surface
 temperatures of around 29C and through an area of low vertical wind
 shear during the next day or so.  These conditions favor some
 strengthening, but eyewall replacement cycles could cause some
 fluctuations in intensity during that time. After that time, an
 increase in southwesterly shear, upwelling, and interaction with
 land is likely to lead to some weakening, however, Florence is
 expected to remain a dangerous major hurricane as it approaches the
 coastline.  The new NHC intensity forecast is near the higher
 statistical guidance through 48 hours, then follows the trend of
 the decay SHIPS model after that time.
 
 Florence is moving west-northwestward or 300 degrees at 15 kt.
 There has been no change to the track forecast or reasoning for the
 first 36-48 hours, as Florence will continue to be steered
 west-northwestward to northwestward around the southwestern portion
 of a mid-level ridge centered northeast of Bermuda.  By late
 Thursday, a mid-level ridge is forecast to begin building over the
 east-central United States, which is expected to cause Florence
 to slow down significantly by 48 hours.  The track guidance is in
 good agreement through the first couple of days of the forecast
 period, and the NHC track forecast again brings the center of the
 hurricane very close to the coasts of North and South Carolina
 within 48 hours.  Later in the period, the dynamical model spread
 increases but most of the guidance has continued its southward
 shift, and now take Florence southwestward near the coast of South
 Carolina by day 4.  The NHC track has been adjusted southward at
 days 4 and 5, and is a little north of the consensus out of respect
 for continuity, however, the GFS, ECMWF, and the ECMWF ensemble mean
 is south of the NHC track forecast, and additional southward
 adjustment may be warranted in future advisories.
 
 It is important for users to realize that significant impacts extend
 well away from the center of Florence, and serious hazards such as
 a dangerous storm surge and flooding rains will cover a large area
 regardless of exactly where the center moves.
 
 Key Messages:
 
 1. A life-threatening storm surge is now highly likely along
 portions of the coastlines of South Carolina and North Carolina, and
 a Storm Surge Warning is in effect for a portion of this area.  All
 interests from South Carolina into the mid-Atlantic region should
 complete preparations and follow any advice given by local
 officials.
 
 2. Life-threatening, catastrophic flash flooding and significant
 river flooding is likely over portions of the Carolinas and
 Mid-Atlantic states from late this week into early next week, as
 Florence is expected to slow down as it approaches the coast and
 moves inland.
 
 3. Damaging hurricane-force winds are likely along portions of the
 coasts of South Carolina and North Carolina, and a Hurricane Warning
 is in effect.  Strong winds could also spread inland into portions
 of the Carolinas.
 
 4. Large swells affecting Bermuda and portions of the U.S. East
 Coast will continue this week, resulting in life-threatening surf
 and rip currents.
 
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  12/0900Z 29.0N  70.1W  115 KT 130 MPH
  12H  12/1800Z 30.3N  72.1W  120 KT 140 MPH
  24H  13/0600Z 32.0N  74.4W  125 KT 145 MPH
  36H  13/1800Z 33.2N  76.1W  120 KT 140 MPH
  48H  14/0600Z 33.8N  77.3W  105 KT 120 MPH...NEAR THE COAST
  72H  15/0600Z 33.8N  78.2W   85 KT 100 MPH...NEAR THE COAST
  96H  16/0600Z 33.6N  79.7W   45 KT  50 MPH...INLAND
 120H  17/0600Z 34.2N  82.7W   25 KT  30 MPH...INLAND
 
 $$
 Forecaster Brown