716 
 WTNT44 KNHC 080858
 TCDAT4
 
 HURRICANE MATTHEW DISCUSSION NUMBER  41
 NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142016
 500 AM EDT SAT OCT 08 2016
 
 Coastal Doppler weather radars this morning continue to depict a
 40-nmi wide eye with a band of intense convection located in the
 northwestern quadrant along the coasts of extreme eastern Georgia
 and South Carolina from Tybee Island northeast to near the entrance
 of Charleston Harbor. Air Force Reserve and NOAA reconnaissance wind
 data, along with Doppler radar velocity data and surface
 observations, indicate that hurricane-force wind gusts in excess of
 80 kt are occuring along the aforementioned coastal areas. Based on
 700-mb maximum flight-level winds of 108 kt, peak SFMR surface winds
 of 83 kt, and Doppler velocities of 100-102 kt between 8000-11000
 ft, the initial intensity will remain at 90 kt for this advisory.
 
 The initial motion estimate is 015/10 kt. Matthew made a northward
 jog since the previous advisory, but now appears to moving
 north-northeastward based on the latest radar and recon fixes.
 However, the more northward motion earlier has increased the
 possibility that the center of Matthew's eye will move onshore the
 coast of South Carolina later this morning or early afternoon as the
 cyclone turns northeastward ahead of a strong shortwave trough.
 Regardless of whether or not the center makes landfall,
 hurricane-force winds in the northern eyewall will lash much of the
 coast of South Carolina today as the center moves to a position just
 east of Charleston Harbor in about 12 hours. After that, the models
 are in fair agreement on Matthew turning eastward through 36 hours
 as the cyclone briefly gets captured by the aforementioned shortwave
 trough. However, by 48 hours and beyond, Matthew is expected to
 turn southeastward and southward as the cyclone moves around the
 eastern periphery of an amplifying ridge located east of Florida.
 In the 48-72 hours time period, some erratic motion could occur as
 Matthew and Tropical Storm Nicole briefly undergo some binary
 interaction before separating by 96 hours. The official forecast
 track closely follows a blend of the GFS and ECMWF solutions.
 
 The vertical wind shear is forecast to increase to more than 30 kt
 by 12 hours, which should induce steady weakening. At 48 hours and
 beyond, the SHIPS model is forecasting the shear to increase to
 more than 40 kt, resulting in rapid weakening to remnant low status
 by 120 hours. However, the shear forecast appears to be overdone
 since both the GFS and ECMWF models indicate that Matthew and Nicole
 will both be moving underneath a narrow 200 mb ridge axis, which
 should act to reduce the shear across the two cyclones in the 48-96
 hour period. The official intensity forecast closely follows the
 consensus model IVCN, and maintains Matthew as a tropical cyclone
 throughout the forecast period.
 
 KEY MESSAGES:
 
 1.  The western eyewall of Matthew, which contains hurricane-force
 winds, is now moving over the northern coast of Georgia and
 the southern coast of South Carolina and should spread up the coast
 during the day.
 
 2.  Hurricane winds increase very rapidly with height, and occupants
 of high-rise buildings along the coast are at particular risk of
 strong winds.  Winds at the top of a 30-story building will average
 one Saffir-Simpson category higher than the winds near the surface.
 
 3.  The water hazards remain, even if the core of Matthew remains
 offshore.  These include the danger of life-threatening inundation
 from storm surge, as well as inland flooding from heavy rains from
 Florida to North Carolina.
 
 4.  The National Hurricane Center is issuing Potential Storm Surge
 Flooding Maps, and Prototype Storm Surge Watch/Warning Graphics for
 Matthew.  It is important to remember that the Potential Storm Surge
 Flooding Map does not represent a forecast of expected inundation,
 but rather depicts a reasonable worst-case scenario -- the amount of
 inundation that has a 10 percent chance of being exceeded.
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  08/0900Z 32.0N  80.5W   90 KT 105 MPH
  12H  08/1800Z 32.9N  79.4W   80 KT  90 MPH
  24H  09/0600Z 33.7N  77.1W   70 KT  80 MPH
  36H  09/1800Z 33.4N  75.1W   60 KT  70 MPH
  48H  10/0600Z 32.6N  73.5W   50 KT  60 MPH
  72H  11/0600Z 29.0N  73.5W   40 KT  45 MPH
  96H  12/0600Z 26.0N  75.3W   30 KT  35 MPH
 120H  13/0600Z 25.0N  76.2W   30 KT  35 MPH
 
 $$
 Forecaster Stewart