457 
 WTNT41 KNHC 010250
 TCDAT1
 
 HURRICANE JOAQUIN DISCUSSION NUMBER  13
 NWS NATIONAL HURRICANE CENTER MIAMI FL       AL112015
 1100 PM EDT WED SEP 30 2015
 
 Joaquin has rapidly intensified during the past 24 hours with the
 satellite presentation continuing to improve this evening.  The eye
 has recently become apparent near the center of the very symmetric
 central dense overcast.  An Air Force Reserve Hurricane Hunter
 aircraft that has been investigating the hurricane this evening has
 measured peak 700 mb flight-level winds of 113 kt and 102 kt surface
 winds from the SFMR.  These data support an initial intensity of
 100 kt, making Joaquin the second major hurricane of the 2015
 Atlantic hurricane season. NOTE: Communications problems have
 delayed the public release of the Air Force reconnaissance data.
 
 Joaquin continues to move slowly southwestward with an initial
 motion estimate of 220/5 kt.  The hurricane is forecast to move
 slowly southwestward or west-southwestward for another 24 hours or
 so while it remains to the south of a narrow northeast to southwest
 oriented ridge.  This ridge is expected to weaken by Friday as a
 trough deepens and cuts off over the southeastern United States.
 This should cause Joaquin to turn northward within 48 hours. The 18Z
 runs of the GFS and HWRF remain in general agreement with the 12Z
 UKMET and Canadian models moving Joaquin around the northeastern
 portion of the cut-off low and bring the hurricane inland over the
 Carolinas or mid-Atlantic states.  The 12Z ECMWF remains the outlier
 by showing a track toward the northeast out to sea.  The NHC
 forecast continues to follow the trend of the bulk of the guidance
 and takes Joaquin toward the U.S east coast. The NHC track is
 similar to the previous advisory and is once again east of the
 multi-model consensus.  The NOAA G-IV aircraft has recently
 completed its synoptic surveillance flight, and data collected
 during this mission should be assimilated into the 0000 UTC models,
 hopefully reducing the spread of the track guidance.
 
 The upper-level wind pattern over the hurricane is forecast by the
 global models to become even more conducive during the next couple
 of days.  This favors additional intensification, with the only
 possible limiting factors being upwelling of cool SSTs beneath the
 slow-moving hurricane and eyewall cycles which could cause some
 fluctuations in intensity.  By 72 hours, increasing southwesterly
 shear, dry air intrusion, and lower SSTs are expected to cause
 gradual weakening.  The updated NHC intensity forecast has been
 significantly increased from the previous advisory primarily due to
 the higher initial intensity. The official forecast is between the
 lower statistical guidance and the higher HWRF during the first
 36-48 hours, and is near the SHIPS/LGEM guidance after that time.
 
 
 KEY MESSAGES:
 
 1.  Preparations to protect life and property within the warning
 areas in the Central Bahamas should be completed now.
 
 2.  Confidence in the details of the forecast after 72 hours remains
 low, since we have one normally excellent model that keeps Joaquin
 far away from the United States east coast.   The range of possible
 outcomes is still large, and includes the possibility of a major
 hurricane landfall in the Carolinas.
 
 3.  Every effort is being made to provide the forecast models with
 as much data as possible.  The NOAA G-IV jet has begun a series of
 missions in the storm environment, and the National Weather Service
 has begun launching extra balloon soundings.
 
 4.  Because landfall, if it occurs, is still more than three days
 away, it's too early to talk about specific wind, rain, or surge
 impacts from Joaquin in the United States.  Regardless of Joaquin's
 track, strong onshore winds will create minor to moderate coastal
 flooding along the coasts of the mid-Atlantic and northeastern
 states through the weekend.
 
 5.  A hurricane watch for a portion of the U.S. coast could be
 required as early as Thursday evening.
 
 6. Many portions of the eastern U.S. are currently experiencing
 heavy rains and gusty winds associated with a frontal system. These
 heavy rains are likely to continue for the next few days, even if
 the center of Joaquin stays offshore.  The resulting inland flood
 potential could complicate preparations for Joaquin should it head
 toward the coast, and even more substantial inland flooding is
 possible if Joaquin later passes near or over these same areas.
 
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  01/0300Z 23.8N  73.1W  100 KT 115 MPH
  12H  01/1200Z 23.5N  73.8W  110 KT 125 MPH
  24H  02/0000Z 23.6N  74.5W  120 KT 140 MPH
  36H  02/1200Z 24.7N  74.8W  120 KT 140 MPH
  48H  03/0000Z 26.6N  74.7W  110 KT 125 MPH
  72H  04/0000Z 31.6N  74.7W   95 KT 110 MPH
  96H  05/0000Z 36.2N  75.6W   85 KT 100 MPH
 120H  06/0000Z 38.5N  76.5W   55 KT  65 MPH
 
 $$
 Forecaster Brown