769 
 WTPZ42 KNHC 040244
 TCDEP2
 
 HURRICANE BLANCA DISCUSSION NUMBER  14
 NWS NATIONAL HURRICANE CENTER MIAMI FL       EP022015
 1000 PM CDT WED JUN 03 2015
 
 Blanca's convection has continued to decrease in intensity this
 evening, and the eye observed in infrared satellite imagery has been
 filling.  Dvorak T-numbers have dropped across the board, but the
 intensity is being held at 120 kt based on a blend of current
 intensity numbers.  Microwave imagery does not show the development
 of concentric eyewalls, which often leads to disruptions in
 intensification, but an 0030Z SSMIS pass did indicate that some dry
 air may be wrapping into the circulation.  There's also the
 possibility that upwelling of cooler water could be an issue, but
 it's impossible to know that in real time.
 
 The hurricane has been drifting southwestward during the past 6-12
 hours.  Model guidance is in agreement that Blanca should begin
 to accelerate toward the northwest on Thursday in response to a
 amplifying mid-level trough along the U.S. west coast and building
 high pressure over northern Mexico.  However, some of the track
 models (most notably the GFS, HWRF, and GFDL) have again shifted
 westward a bit.  As a result, the updated NHC track forecast is
 slightly west of the previous forecast between 72-120 hours.
 
 Despite the hurricane's recent convective changes, the microwave
 data showed that the eyewall remains intact, and low vertical shear
 and a generally moist environment should be conducive to support
 further strengthening during the next 36 hours.  In addition, once
 Blanca begins moving toward the northwest, it would escape any
 potential areas of upwelled cooler water.  The GFS, ECMWF, SHIPS,
 and LGEM all show Blanca peaking in intensity at 36 hours, and the
 updated NHC intensity forecast follows suit by showing a maximum
 intensity right near the category 4/5 boundary Friday morning.
 After that, increasing shear, cooler water, and a drier, more stable
 atmosphere should lead to rapid weakening, especially after 72
 hours.
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  04/0300Z 12.0N 104.7W  120 KT 140 MPH
  12H  04/1200Z 12.6N 105.1W  125 KT 145 MPH
  24H  05/0000Z 13.7N 106.0W  130 KT 150 MPH
  36H  05/1200Z 15.0N 107.2W  135 KT 155 MPH
  48H  06/0000Z 16.4N 108.5W  130 KT 150 MPH
  72H  07/0000Z 19.1N 110.2W  100 KT 115 MPH
  96H  08/0000Z 21.9N 111.3W   60 KT  70 MPH
 120H  09/0000Z 24.9N 112.7W   35 KT  40 MPH
 
 $$
 Forecaster Berg