Hurricane NORBERT

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HURRICANE NORBERT DISCUSSION NUMBER   7
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP142014
800 PM PDT WED SEP 03 2014

Norbert continues to intensify this evening.  Evening visible
satellite images showed a symmetric central dense overcast feature
with curved convective bands wrapping around the center. The latest
Dvorak intensity estimates from TAFB, SAB, and UW/CIMMS ADT were
between 65 and 77 kt, and the initial wind speed has been increased
to 70 kt for this advisory.  Norbert is the ninth hurricane to form
in the eastern Pacific basin this season.

The outflow has become well established, except over the
northeastern portion of the cyclone where there is a hint of light
to moderate northeasterly shear. However, the shear is not expected
to be strong enough to inhibit strengthening during the next day or
so while Norbert remains over warm water. The NHC forecast is close
to the SHIPS model through 36 h and is similar to the previous
advisory. After that time, Norbert will be approaching cooler waters
and a drier and more stable airmass, which should cause weakening to
commence. A faster rate of weakening is forecast in 48 to 72 hours
when the cyclone moves over SSTs below 26C.

The hurricane appears to have turned northwestward with an initial
motion of 305/7 kt.  Norbert should continue on a general
northwestward motion during the next several days around the
southwestern periphery of a mid-level ridge that extends westward
across northern Mexico.  The model guidance is in good agreement on
the general heading of the cyclone, although there are some
differences in the forward speed of Norbert later in the period.
Much of the guidance now indicates a faster forward speed late in
the period, with the GFS showing a deeper cyclone moving even faster
and farther north than the ECMWF, UKMET, and HWRF.  The updated NHC
track forecast is a little faster than the previous advisory to be
in better agreement with the multi-model consensus, but is not
nearly as fast as the GFS.

Moisture indirectly related to Norbert being pulled northward
around the eastern side of cyclone's large circulation is expected
to spread across northern Mexico and into the southwestern United
States during the next few days. This could result in heavy rains
and life-threatening flash flooding in these areas. Please see
information from your local weather office for more details.

FORECAST POSITIONS AND MAX WINDS

INIT  04/0300Z 19.9N 109.8W   70 KT  80 MPH
 12H  04/1200Z 20.7N 110.5W   80 KT  90 MPH
 24H  05/0000Z 21.7N 111.4W   85 KT 100 MPH
 36H  05/1200Z 22.8N 112.5W   85 KT 100 MPH
 48H  06/0000Z 23.7N 113.4W   75 KT  85 MPH
 72H  07/0000Z 25.3N 115.5W   55 KT  65 MPH
 96H  08/0000Z 27.0N 117.5W   35 KT  40 MPH
120H  09/0000Z 29.0N 118.5W   30 KT  35 MPH...POST-TROP/REMNT LOW

$$
Forecaster Brown

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