Tropical Storm NORBERT

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TROPICAL STORM NORBERT DISCUSSION NUMBER   6
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP142014
200 PM PDT WED SEP 03 2014

Satellite images indicate that Norbert is still on an
intensification trend.  While no eye is apparent in visible imagery,
recent microwave imagery indicates that an eye is trying to form.
The cyclone has a long curved band around the southern and western
semicircle wrapping into the small central dense overcast.  A blend
of the subjective and objective Dvorak estimates gives 60 kt as the
initial wind speed.

It is hard to find a reason why Norbert will not significantly
intensify during the next day or so since it will remain over very
warm waters, the shear does not appear to be that detrimental, and
it already has many features of an inner core. Yet the best model
guidance is lower than 6 hours ago, with no forecast above 80 kt for
a peak intensity.  With so many favorable environmental factors and
the low model bias observed this season (and this cyclone), the new
NHC forecast will stay close to the previous one.  Weakening should
begin in a few days when Norbert moves over cooler waters and into
the more stable atmosphere of the subtropical eastern Pacific Ocean.

After a brief westward track, Norbert appears to be moving more
to the west-northwest, or 300/6.  Global models are in good
agreement on a weakening ridge over northwestern Mexico forcing the
storm to move northwestward over the next few days.  Model guidance
is well clustered on a track offshore of Baja Califoria Sur, except
for the GFDL which has a known northward bias in this region.
Norbert is still expected to pass close enough to bring tropical-
storm-force winds to portions of the state. The new forecast is a
little farther south of the previous one during the first 24 hours,
mostly because of the earlier westward motion.  Little change has
been made to the rest of the forecast, which is just to the west of
the dynamical track consensus.

Moisture from the combination of Norbert and the remnants of
Atlantic Tropical Storm Dolly is expected to spread northwestward
across northern Mexico during the next couple of days, and into the
southwestern United States over the weekend.  Heavy rain causing
life-threatening flash flooding are possible in those regions.
Please see information from your local weather office for more
details.


FORECAST POSITIONS AND MAX WINDS

INIT  03/2100Z 19.6N 109.2W   60 KT  70 MPH
 12H  04/0600Z 20.1N 110.0W   70 KT  80 MPH
 24H  04/1800Z 20.9N 110.8W   85 KT 100 MPH
 36H  05/0600Z 21.9N 111.6W   90 KT 105 MPH
 48H  05/1800Z 23.0N 112.6W   85 KT 100 MPH
 72H  06/1800Z 24.5N 114.5W   65 KT  75 MPH
 96H  07/1800Z 26.0N 116.7W   45 KT  50 MPH
120H  08/1800Z 28.0N 118.0W   35 KT  40 MPH

$$
Forecaster Blake

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