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HURRICANE SANDRA DISCUSSION NUMBER  15
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP222015
200 AM MST FRI NOV 27 2015

It appears that the strong shear is finally affecting the structure
of the hurricane. The cloud pattern has rapidly deteriorated and the
eye is no longer observed. In fact, most of the deep convection is
now on the northeastern portion of the cyclone. Both objective and
subjective numbers are decreasing, and the initial intensity has
been lowered to 90 kt.  The shear is forecast to increase even more,
and most of the global models continue to separate the surface
center from the mid-level circulation. As suggested by guidance, the
NHC forecast calls for weakening and brings Sandra near the coast of
mainland Mexico below tropical storm strength.

Satellite fixes indicate that Sandra has been moving toward the
north-northeast of 020 degrees at 10 kt. The cyclone is already
embedded within the broad southwesterly flow ahead of a large
mid-latitude trough, and no significant change in the steering
pattern is anticipated. On this basis, the NHC forecast keeps this
general motion until the center of the cyclone reaches the coast of
Mexico in about 36 hours. The NHC forecast is a little bit east of
the previous one, and is basically on top of the multi-model
consensus. The ECMWF model has shifted a little bit eastward
in the last run, but still is on the western edge of dynamical
guidance envelope.

Given the eastward shift in the forecast track, the expected
weakening, and the likely decay of the wind field to the west of
the center, it is becoming less likely that a tropical storm warning
will be required for southern the Baja California peninsula later
this morning.

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


FORECAST POSITIONS AND MAX WINDS

INIT  27/0900Z 18.9N 109.3W   90 KT 105 MPH
 12H  27/1800Z 20.5N 108.8W   70 KT  80 MPH
 24H  28/0600Z 22.3N 108.3W   45 KT  50 MPH
 36H  28/1800Z 24.2N 108.0W   30 KT  35 MPH
 48H  29/0600Z 26.5N 107.5W   20 KT  25 MPH...POST-TROP/INLAND
 72H  30/0600Z...DISSIPATED

$$
Forecaster Avila

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