508 
 WTNT41 KNHC 012045
 TCDAT1
 
 HURRICANE JOAQUIN DISCUSSION NUMBER  16
 NWS NATIONAL HURRICANE CENTER MIAMI FL       AL112015
 500 PM EDT THU OCT 01 2015
 
 The earlier Air Force Reserve Hurricane Hunter aircraft reported
 700-mb flight-level winds of 120 kt in the southwestern eyewall,
 with a subsequent 114-kt surface wind estimate from the Stepped
 Frequency Microwave Radiometer in the southeastern eyewall.  The
 last central pressure extrapolated from the aircraft data was 936
 mb.  In addition, satellite intensity estimates from TAFB, SAB,
 and CIMSS are now in the 115-127 kt range.  Based on these data, the
 intensity was increased to 115 kt at 1800 UTC, making Joaquin a
 Category 4 hurricane.  While this advisory will not increase the
 intensity any further, it is expected that the next aircraft
 arriving in the hurricane near 0000 UTC will find a stronger system.
 
 Joaquin is expected to intensify a little more during the next 12
 hours or so as it remains over very warm waters and in an
 environment of decreasing vertical shear.  After that time, there
 could be some fluctuations in intensity due to eyewall replacement
 cycles.  While there remains some uncertainty regarding the
 intensity in the 48-96 hour range, the new forecast is
 similar to the previous forecast in calling for a steady weakening
 during this period.  Overall, the intensity forecast lies near the
 upper edge of the guidance envelope.
 
 Joaquin has moved with a more westward component during the past few
 hours and the initial motion is now 235/5.  Water vapor imagery
 shows a mid- to upper-level ridge north of the hurricane, with a
 developing deep-layer trough over the eastern and southeastern
 United States. The dynamical models forecast this trough to become a
 cut-off low as it moves southeastward and weakens the ridge.  This
 pattern evolution should cause Joaquin to turn northward in 12-24
 hours. The guidance after 48 hours has changed somewhat since the
 last advisory, with the GFS and the UKMET moving farther to the east
 and lying closer to the ECMWF.  In addition, the HWRF has made a
 big jump to the east and now shows an offshore track.  These changes
 have pushed the consensus models farther eastward.
 The Canadian, GFDL, and NAVGEM models are holdouts, however - still
 calling for Joaquin to interact with the United States trough and
 turn northwestward toward the U. S. coast.  The new forecast track
 is adjusted to the east of the previous forecast between 48-120
 hours, but it still lies well to the left of the GFS, UKMET, ECMWF,
 HWRF, and the consensus models. Further eastward adjustments to the
 track are likely.
 
 
 KEY MESSAGES:
 
 1.  Joaquins slow motion means that extremely dangerous conditions
 will continue over portions of the warning areas in the Bahamas well
 into Friday.
 
 2.  A strong majority of the forecast models are now in agreement on
 a track farther away from the United States east coast.   We are
 becoming optimistic that the Carolinas and the mid-Atlantic states
 will avoid the direct effects from Joaquin.  However, we cannot yet
 completely rule out direct impacts along on the east coast, and
 residents there should continue to follow the progress of Joaquin
 over the next couple of days.
 
 3.  Efforts to provide the forecast models with as much data as
 possible continue, with twice daily NOAA G-IV jet missions in the
 storm environment, and extra NWS balloon launches.
 
 4.  Even if Joaquin moves out to sea, strong onshore winds
 associated with a frontal system will create minor to moderate
 coastal flooding along the coasts of the mid-Atlantic and
 northeastern states through the weekend.  In addition, very heavy
 rains, not associated with Joaquin, are expected to produce flooding
 over portions of the Atlantic coastal states.  Please see products
 issued by local NWS Forecast Offices.
 
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  01/2100Z 23.0N  74.4W  115 KT 130 MPH
  12H  02/0600Z 23.2N  74.7W  120 KT 140 MPH
  24H  02/1800Z 24.4N  74.7W  120 KT 140 MPH
  36H  03/0600Z 25.9N  74.1W  120 KT 140 MPH
  48H  03/1800Z 28.4N  73.3W  110 KT 125 MPH
  72H  04/1800Z 33.0N  72.5W   90 KT 105 MPH
  96H  05/1800Z 37.0N  72.0W   70 KT  80 MPH
 120H  06/1800Z 41.0N  69.0W   55 KT  65 MPH
 
 $$
 Forecaster Beven