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HURRICANE BLANCA DISCUSSION NUMBER  19
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP022015
300 AM MDT FRI JUN 05 2015

The convective structure of Blanca has improved during the past few
hours, with an increase in the coverage of cold cloud tops around a
ragged eye in geostationary imagery. The initial intensity is set to
90 kt based on a blend of the latest Dvorak estimates from TAFB and
SAB (77 kt) and the latest UW-CIMSS ADT estimates of around 100 kt.
An Air Force Reserve Hurricane Hunter aircraft is scheduled to
investigate Blanca later today to provide more information on the
intensity and structure of the cyclone. The initial 34-kt and 50-kt
wind radii are based on data from ASCAT-A and ASCAT-B passes.

The environment of low shear and warm SSTs should support some
additional intensification during the next 24 hours or so. However,
given the somewhat ragged appearance of the inner core on microwave
imagery, only slight strengthening is shown in the official
forecast, and even this is a bit above all of the guidance. By 36
hours the shear increases while the cyclone begins to move over
cooler SSTs and into a drier airmass. This combination of factors
should result in weakening, which should accelerate by 48 hours
after Blanca crosses the 26C SST isotherm.

The initial motion estimate is 320/09. Blanca is forecast to move
generally northwestward to north-northwestward during the next
several days, as it is steered by a ridge centered over northern
Mexico and a trough west of the Baja California peninsula. There
continues to be some spread in the guidance beyond 48 hours, likely
due to differences in the extent of mid-level ridging north of
Blanca. The ECMWF has trended a bit to the right this cycle but is
still slower and west of the consensus, while the UKMET is even
farther to the west. The GFS, GEFS mean, HWRF and GFDL continue to
cluster farther right and faster. The new NHC track forecast is
largely an update of the previous one through 48 hours and has
been shifted a little to the right after that time. The official
forecast is close to TVCE multi-model consensus through the period.

Moisture associated with Blanca is moving northward and could help
produce heavy rainfall over portions of southwestern Mexico during
the next day or so, especially in areas of mountainous terrain.

FORECAST POSITIONS AND MAX WINDS

INIT  05/0900Z 14.3N 106.2W   90 KT 105 MPH
 12H  05/1800Z 15.4N 107.2W   95 KT 110 MPH
 24H  06/0600Z 16.9N 108.6W   95 KT 110 MPH
 36H  06/1800Z 18.4N 109.5W   90 KT 105 MPH
 48H  07/0600Z 20.0N 110.1W   75 KT  85 MPH
 72H  08/0600Z 23.7N 111.1W   50 KT  60 MPH
 96H  09/0600Z 26.5N 112.3W   35 KT  40 MPH...INLAND
120H  10/0600Z 28.0N 113.5W   20 KT  25 MPH...POST-TROP/INLAND

$$
Forecaster Brennan

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