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HURRICANE SANDRA DISCUSSION NUMBER  12
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP222015
800 AM MST THU NOV 26 2015

Sandra has begun to fill.  The well-defined eye seen in conventional
satellite imagery overnight has since disappeared while the shape
and distribution of deep convection within the central dense
overcast has become asymmetric.  The onset of weakening coincides
with an increase in southwesterly vertical shear as depicted in
UW-CIMSS shear analyses now that Sandra is well north of the
upper-level ridge axis.  Dvorak intensity estimates are decreasing,
and the initial intensity is lowered to 115 kt in agreement with the
latest TAFB satellite classification.

Sandra has begun to recurve, with an initial motion estimate of
005/10.  The cyclone is currently being steered by the southerly
flow on the western periphery of a mid-level ridge located over the
western Gulf of Mexico.  Within 24 hours, Sandra should become
embedded in the fast-paced and deep-layer southwesterly flow ahead
of a trough over the western United States, which should result in
a north-northeastward motion that should continue until dissipation
over northwestern Mexico.  The new track forecast is adjusted to the
right of the previous one and is on the eastern edge of the guidance
envelope.

As Sandra gains latitude during the next 24 hours, a sharp increase
in southwesterly shear should contribute to rapid weakening of the
cyclone.  By the time Sandra reaches 20N latitude just after 24
hours, very strong shear associated with the western United States
trough should result in an abrupt decoupling of the low- to mid-
level circulations and a destruction of the cyclone's warm core by
48 hours.  The remnant circulation, likely devoid of convection, is
expected to reach the coast of northwestern Mexico just beyond 48
hours and quickly dissipate over the high terrain of the Sierra
Madre Occidental after moving inland.  The new intensity forecast
shows an even quicker rate of weakening than the previous one and is
lower the the multi-model consensus and the remainder of the
intensity guidance.

FORECAST POSITIONS AND MAX WINDS

INIT  26/1500Z 15.7N 110.1W  115 KT 130 MPH
 12H  27/0000Z 17.3N 110.0W  100 KT 115 MPH
 24H  27/1200Z 19.3N 109.7W   75 KT  85 MPH
 36H  28/0000Z 21.2N 108.9W   50 KT  60 MPH
 48H  28/1200Z 23.4N 107.7W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  29/1200Z 28.1N 104.9W   15 KT  15 MPH...POST-TROP/REMNT LOW
 96H  30/1200Z...DISSIPATED

$$
Forecaster Kimberlain

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