704 
 WTNT41 KNHC 010849
 TCDAT1
 
 HURRICANE JOAQUIN DISCUSSION NUMBER  14
 NWS NATIONAL HURRICANE CENTER MIAMI FL       AL112015
 500 AM EDT THU OCT 01 2015
 
 Data from the last aircraft mission indicated the Joaquin had
 strengthened a little more, and the intensity of 105 kt is supported
 by flight-level, SFMR, and dropsonde data from the plane. The
 central pressure of 948 mb is based on a dropsonde that measured 950
 mb with 20 kt of wind. The satellite presentation of the hurricane
 continues to gradually improve, with cold tops expanding near and
 west of the center, although the eye is not yet apparent in infrared
 imagery. Another hurricane hunter aircraft will be investigating
 Joaquin later this morning.
 
 Joaquin is expected to intensify a little more in the next 12 to 24
 hours while over very warm waters and with decreasing vertical
 shear. After that time, there could be some fluctuations in
 intensity due to eyewall replacement cycles and perhaps some
 upwelling of cold waters due to the slow motion of the hurricane.
 After 48 hours, cooler SSTs and increasing shear should result in
 gradual weakening as Joaquin moves northward. The new NHC intensity
 forecast is similar to the previous one and close to the HWRF
 through 24 hours. After that time, the NHC prediction is above the
 intensity consensus since the official forecast keeps the cyclone
 offshore, while the remainder of the intensity guidance shows
 weakening due to decay over land.
 
 The initial motion of the hurricane is still toward the southwest
 or 230/04 under the influence of a narrow ridge to the north. A
 slow motion with a bending of the track toward the west and then
 the west-northwest is expected during the next 24 hours as the
 ridge weakens. During this time the NHC track has been adjusted
 southward following the latest trend in the guidance. The slow
 motion of Joaquin will mean a prolonged period of hurricane
 conditions in portions of the central Bahamas, along with very heavy
 rain and storm surge.
 
 By 36 hours, Joaquin should begin to move faster toward the north as
 it comes under the influence of a deep-layer trough that cuts off
 over the southeastern United States. There have been big changes in
 some of the track guidance overnight, perhaps due to data from the
 synoptic surveillance mission flown by the NOAA G-IV jet for the 00Z
 model cycle. In particular, the GFS and UKMET have shifted eastward
 by several hundred miles in 3 to 4 days relative to their previous
 solutions. Overall for this cycle there has been a spreading out of
 the guidance envelope beyond 2 days, with a wide range of solutions
 shown. The HWRF and GFDL are the fastest to bring Joaquin north out
 of the Bahamas and still show a sharp westward turn taking the
 cyclone inland over the Carolinas in 3 to 4 days. The GFS has
 trended slower coming out of the Bahamas and now shows a track
 toward Long Island and southern New England in 5 days, with the
 UKMET farther offshore. The latest ECMWF is still the slowest and
 farthest east with a track just west of Bermuda in 4 to 5 days.
 Given the large shift in some of the guidance, the NHC track has
 been adjusted just a little to the east and slower at days 3 through
 5, and now lies on the left side of the multi-model consensus and
 left of the GFS, UKMET and ECMWF solutions. Confidence remains very
 low in the eventual track of Joaquin and any potential impacts for
 the United States, and further adjustments to the NHC track may be
 needed later today.
 
 KEY MESSAGES:
 
 1.  Preparations to protect life and property in the central Bahamas
 should be complete.  The slow motion of Joaquin during the next 24
 to 36 hours will bring a prolonged period of hurricane force winds,
 storm surge, and very heavy rainfall to those islands.
 
 2.  Confidence in the details of the forecast after 72 hours remains
 low, as there have been some large changes in the model guidance
 overnight.  The range of possible outcomes is still large, and
 the possibility of a hurricane landfall in the Carolinas still
 cannot be ruled out.
 
 3.  Efforts continue to provide the forecast models with as much
 data as possible.  The NOAA G-IV jet flew the first in a series of
 missions in the storm environment last night, and these missions
 will continue today.  The National Weather Service also continues to
 launch 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 tonight.
 
 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  01/0900Z 23.4N  73.7W  105 KT 120 MPH
  12H  01/1800Z 23.1N  74.2W  115 KT 130 MPH
  24H  02/0600Z 23.4N  74.8W  120 KT 140 MPH
  36H  02/1800Z 25.0N  74.8W  120 KT 140 MPH
  48H  03/0600Z 26.8N  74.1W  110 KT 125 MPH
  72H  04/0600Z 32.5N  74.0W   95 KT 110 MPH
  96H  05/0600Z 36.0N  74.5W   80 KT  90 MPH
 120H  06/0600Z 39.0N  74.0W   60 KT  70 MPH
 
 $$
 Forecaster Brennan