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HURRICANE ANDRES DISCUSSION NUMBER  12
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP012015
800 PM PDT SAT MAY 30 2015

Andres has strengthened further today despite moderate northwesterly
shear. The cyclone had been maintaining a symmetric central dense
overcast (CDO), and the eye had slowly warmed until about 0000 UTC.
Over the past few hours though, the CDO has become more irregularly
shaped and the eye more indistinct. Dvorak T-numbers were 5.5/102 kt
at 0000 UTC from both agencies, and UW-CIMSS ADT values leveled off
at 5.7/107 kt. These data suggest that Andres may have been a major
hurricane at that time, but satellite data suggest that the cyclone
has since begun to weaken. The initial intensity is set at 95 kt,
slightly lower than 0000 UTC intensity estimates.

Andres is still moving generally northwestward in response to a
weakness in the subtropical ridge around 120w. Most of the track
guidance shows a high pressure ridge north of the cyclone
strengthening on Sunday which should cause the cyclone to turn
west-northwestward. Beyond 48 hours, the track models significantly
diverge, with the GFS-based guidance depicting a stronger cyclone
being steered northwestward over cool waters, followed by an
eastward turn. The ECMWF shows a weaker version of Andres eventually
turning westward, with its solution on the southern side of the
guidance envelope.  The official NHC forecast is close to the multi-
model consensus (TVCE) through 36 hours.  After that, the overly
strong GFS run is disregarded, resulting in a track forecast
relatively far left of TVCE.

The shear over Andres is forecast to decrease dramatically within
24 hours, but the cyclone will be moving over gradually cooler
waters and ingesting drier and more stable air during the next
couple of days.  This competition between dynamic and thermodynamic
factors should result in a slow weakening through 48 hours. After
that time, even more unfavorable thermodynamic conditions could
result in a quicker rate of weakening, and Andres is expected to
become a remnant low by day 5.  The NHC intensity forecast is
close to LGEM and somewhat lower than the multi-model consensus
ICON.

FORECAST POSITIONS AND MAX WINDS

INIT  31/0300Z 15.1N 116.8W   95 KT 110 MPH
 12H  31/1200Z 15.6N 117.8W   95 KT 110 MPH
 24H  01/0000Z 16.1N 119.1W   85 KT 100 MPH
 36H  01/1200Z 16.5N 120.4W   75 KT  85 MPH
 48H  02/0000Z 17.0N 122.0W   65 KT  75 MPH
 72H  03/0000Z 18.4N 125.1W   50 KT  60 MPH
 96H  04/0000Z 19.3N 128.2W   35 KT  40 MPH
120H  05/0000Z 19.3N 130.1W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Kimberlain

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