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HURRICANE BLANCA DISCUSSION NUMBER  10
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP022015
1000 PM CDT TUE JUN 02 2015

An 0100Z SSMIS pass revealed that the mid-level eye which was
observed earlier today has shrunk, and spiral convective bands are
emanating away from the central convection, favoring the southern
semicircle.  Dvorak estimates from TAFB and SAB have increased to
T4.5/77 kt, so Blanca's initial intensity is raised to 75 kt.  This
is the first instance in which Blanca's intensity has increased by
at least 30 kt over a 24-hour period, so it appears that the
hurricane is now experiencing the period of rapid intensification
that has been forecast.

Rapid intensification is expected to continue for at least the next
24-36 hours due to an environment of negligible vertical shear,
deep warm water, and abundant atmospheric moisture.  Because of
these conditions, the statistical-dynamical models (SHIPS, LGEM,
and Florida State Superensemble) all show Blanca reaching major
hurricane strength in the next 18-24 hours and then peaking at
category 4 strength in about 48 hours.  Meanwhile, for reasons that
are unclear at the moment, the HWRF and GFDL models keep Blanca
essentially steady at category 1 strength for the next four days.
Since there are no apparent reasons why the environment shouldn't
support strengthening, the official forecast is a blend of the
statistical-dynamical models and is just a little higher than the
previous forecast during the first 48 hours.  By days 4 and 5,
increasing vertical shear and sub-optimal sea surface temperatures
should cause Blanca to weaken fairly quickly while it approaches
the Baja California peninsula.

Blanca appears to have drifted southwestward during the past 12-18
hours, and the hurricane is expected to move little during the next
24 hours.  After that time, a deepening trough along the U.S. west
coast should cause Blanca to accelerate gradually and move north-
northwestward between 36-120 hours.  With the exception of the GFDL
and UKMET models, there is very little cross-track variability
among the other reliable track models, but there are some
differences in forward speed.  The GFS continues to be one of the
fastest models, while the ECMWF is one of the slowest and doesn't
show Blanca reaching the Baja California peninsula during the
five-day forecast period.  Since the 00Z multi-model consensus
(TVCE) is very close to the previous NHC forecast (OFCI), I elected
not to make any significant changes to the track forecast on this
cycle.

Even though Blanca's forecast track has not shifted eastward, there
is the potential for the tropical-storm-force wind field to expand
in that direction during the next few days.  Therefore, interests
along the west-central coast of mainland Mexico, especially in the
state of Jalisco, should monitor the progress of Blanca.

FORECAST POSITIONS AND MAX WINDS

INIT  03/0300Z 12.8N 104.7W   75 KT  85 MPH
 12H  03/1200Z 12.7N 104.7W   95 KT 110 MPH
 24H  04/0000Z 12.8N 104.7W  110 KT 125 MPH
 36H  04/1200Z 13.4N 105.0W  120 KT 140 MPH
 48H  05/0000Z 14.7N 105.8W  125 KT 145 MPH
 72H  06/0000Z 17.5N 108.2W  110 KT 125 MPH
 96H  07/0000Z 20.5N 109.5W   85 KT 100 MPH
120H  08/0000Z 23.5N 110.5W   55 KT  65 MPH

$$
Forecaster Berg

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