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Hurricane SANDRA Forecast Discussion

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WTPZ42 KNHC 271435

800 AM MST FRI NOV 27 2015

The coverage of cold cloud tops within the CDO of Sandra continues
to decrease, and the southwestern portion of the CDO has eroded due
to about 30 kt of southwesterly shear. An 1133Z SSMIS image also
showed that the eye had become less distinct. Dvorak intensity
estimates continue to decrease, and based on a blend of the latest
Final-T and CI numbers the initial intensity has been lowered to 85
kt, and this could be a bit generous. Quick weakening is expected
during the next 24 hours as the shear is forecast to increase to 40
to 45 kt. This should result in the low-level circulation of Sandra
decoupling from the mid-level circulation before it reaches the
coast. Sandra is forecast to weaken to a tropical storm later today
and continue to weaken as it approaches the coast of Mexico in about
24 hours, but is still expected to be a tropical storm.  After
landfall, the low-level circulation should quickly dissipate,
although a 36-hour forecast point was provided to show the system
moving inland. The new NHC intensity forecast is close to a blend of
the HWRF, SHIPS and LGEM models.

Sandra has moved to the right of the previous forecast track, and
the initial motion estimate is 030/10. Sandra should continue to
recurve between a mid-level ridge centered over the western Gulf of
Mexico and a broad deep-layer trough over western North America.
Given the initial motion, the new NHC track forecast has been
adjusted to the right of the previous one and now lies to the right
of the latest multi-model consensus. The official forecast favors
the GFS and HWRF models, which have the best handle on the initial
motion. This adjustment to the track will bring the center of Sandra
to the coast of Mexico in about 24 hours.

Given the eastward shift in the forecast track and the expectation
that Sandra will still be a tropical storm as it nears the coast,
the Government of Mexico has issued a tropical storm warning for Las
Islas Marias and part of the coasts of the states of Sinaloa and
Nayarit. Regardless of Sandra's intensity at landfall, the main
threat will be heavy rains across portions of several Mexican

The remnant mid- and upper-level moisture associated with Sandra
will contribute to a significant precipitation event expected to
occur over portions of the south-central United States this weekend.
For more information, please see products from the NOAA Weather
Prediction Center and local NWS Weather Forecast Offices.


INIT  27/1500Z 19.6N 108.4W   85 KT 100 MPH
 12H  28/0000Z 21.4N 107.7W   60 KT  70 MPH
 24H  28/1200Z 23.5N 106.7W   40 KT  45 MPH
 36H  29/0000Z 25.8N 105.0W   20 KT  25 MPH...POST-TROP/INLAND
 48H  29/1200Z...DISSIPATED

Forecaster Brennan