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Post-Tropical Cyclone SANDRA Forecast Discussion


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000
WTPZ42 KNHC 281432
TCDEP2

POST-TROPICAL CYCLONE SANDRA DISCUSSION NUMBER  20
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP222015
800 AM MST SAT NOV 28 2015

Sandra has been devoid of organized deep convection since about
0000 UTC, a little after the time that the low- and mid-level
circulations separated from one another. With west-southwesterly
vertical wind shear of nearly 50 kt and forecast to increase
further, regeneration is unlikely. Sandra is therefore being
declared a post-tropical remnant low, and this is the last advisory
on this system. Some spin-down of the vortex is assumed since the
overnight ASCAT pass that showed tropical-storm-force winds, and the
initial intensity estimate is lowered to 30 kt.  Global models show
the remnant low of Sandra weakening further and dissipating in about
24 hours near the coast of Sinaloa.

The initial motion of the post-tropical cyclone is toward the north
or 010/06. The remnant low should turn north-northeastward around a
low-level ridge located near the south-central coast of Mexico, and
this motion should continue until dissipation.  The new track
forecast is adjusted slightly to the right of the previous one
toward the multi-model consensus.

Moisture associated with the remnants of Sandra's mid- and
upper-level circulations could still produce heavy rains over
portions of central Mexico during the next day or so, potentially
causing localized flash flooding and mud slides.  The remnant
moisture could also contribute to the significant heavy rain event
already occurring over the south-central United States. For more
information, please see products from the NOAA Weather Prediction
Center and local NWS Weather Forecast Offices.

For additional information on the remnant low, please see High Seas
Forecasts issued by the National Weather Service, under AWIPS
header NFDHSFEP1, WMO header FZPN01 KWBC, and on the web at
http://www.opc.ncep.noaa.gov/shtml/NFDHSFEP1.shtml.

FORECAST POSITIONS AND MAX WINDS

INIT  28/1500Z 22.0N 108.9W   30 KT  35 MPH...POST-TROP/REMNT LOW
 12H  29/0000Z 23.3N 108.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 24H  29/1200Z 24.3N 107.9W   20 KT  25 MPH...POST-TROP/REMNT LOW
 36H  30/0000Z...DISSIPATED

$$
Forecaster Kimberlain