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TROPICAL STORM NORBERT DISCUSSION NUMBER  21
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP142014
800 AM PDT SUN SEP 07 2014

Deep convection has been decreasing quickly during the last several
hours, and only a small area of cold cloud tops remains to the
south of the center.  Satellite intensity estimates are falling, and
the initial wind speed is lowered to 50 kt using an average of the
Dvorak CI-numbers from TAFB, SAB, and UW-CIMSS. The quick weakening
of Norbert is due to the influence of cool waters of around 25 C and
a dry stable air mass.  These factors will become even more
unfavorable along the expected track of Norbert, and should cause
the cyclone to degenerate to a remnant low in about 24 hours, or
maybe even sooner. Once Norbert becomes a remnant low, the cyclone
is expected to slowly spin down and then open into a trough in about
4 days. The NHC intensity forecast is lower than the previous one,
mainly due to the observed rate of weakening.

Norbert is still moving west-northwestward, but it is expected to
turn toward the northwest and then north during the next day or so
when it feels the influence of a deep-layer trough west of
California.  A slow down and turn toward the northeast or east is
expected after that time when the shallow system is steered by the
low-level flow toward the Baja California peninsula.  No significant
change was made to the previous track forecast, and it lies close to
the GFS/ECMWF consensus.

Although the system is weakening quickly, tropical moisture
associated with Norbert and the Pacific ITCZ will continue to
spread northward across northern Mexico and the southwestern United
States.  This could result in heavy rains and life-threatening flash
flooding in these area during the next day or two. Please see
information from your local weather office for more details.

FORECAST POSITIONS AND MAX WINDS

INIT  07/1500Z 26.0N 117.0W   50 KT  60 MPH
 12H  08/0000Z 26.9N 117.7W   35 KT  40 MPH
 24H  08/1200Z 27.9N 118.2W   30 KT  35 MPH...POST-TROP/REMNT LOW
 36H  09/0000Z 28.5N 118.2W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  09/1200Z 29.1N 117.6W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  10/1200Z 29.5N 116.6W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  11/1200Z...DISSIPATED

$$
Forecaster Cangialosi

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