Tropical Storm NORBERT

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TROPICAL STORM NORBERT DISCUSSION NUMBER   5
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP142014
800 AM PDT WED SEP 03 2014

Norbert has become significantly better organized this morning.
The central dense overcast has become more symmetric with more
prominent banding around the center.  Microwave images also show
that the inner core is becoming better defined, with the likely
first stages of a primitive eye.  The initial wind speed is set to
55 kt, at the top end of the subjective Dvorak estimates, although
the latest objective numbers are higher.  With the improvement in
the inner core, light-to-moderate shear, and very warm waters,
future strengthening seems quite likely.  In fact, rapid
intensification is a distinct possibility, with the SHIPS-RI
showing about a 1-in-3 chance of Norbert becoming 30 kt stronger in
the next 24 hours.  Considering the environmental factors and the
low bias of the deterministic guidance so far, the new NHC intensity
forecast is raised considerably from the previous one, about 5 kt
above the highest guidance through 48 hours.  After that time,
cooler waters and a more stable atmosphere are expected to weaken
the cyclone.  The NHC forecast is blended with the previous
forecast and the intensity consensus at long range.

With recent microwave and visible imagery, it appears that Norbert
has been moving westward over the past few hours.  However, a more
representative long-term motion is 295/8.  Mid-level ridging is
expected to weaken later today over northwestern Mexico, which
should cause Norbert to turn more to the northwest.  While all of
the reliable guidance keeps the center of the storm offshore of Baja
California Sur, Norbert should come close enough to bring tropical-
storm-force winds to the state.  The models have shifted somewhat
southward since the last cycle, and with the recent westward motion,
it makes sense to adjust the NHC forecast a little farther south for
the first day or so.  There hasn't been much change to the guidance
beyond day 3, so the new forecast is basically an update to the
previous one.

FORECAST POSITIONS AND MAX WINDS

INIT  03/1500Z 19.6N 108.8W   55 KT  65 MPH
 12H  04/0000Z 20.1N 109.6W   65 KT  75 MPH
 24H  04/1200Z 20.9N 110.3W   80 KT  90 MPH
 36H  05/0000Z 21.8N 111.0W   90 KT 105 MPH
 48H  05/1200Z 22.6N 111.9W   90 KT 105 MPH
 72H  06/1200Z 24.4N 113.9W   70 KT  80 MPH
 96H  07/1200Z 25.6N 116.2W   55 KT  65 MPH
120H  08/1200Z 27.0N 117.5W   40 KT  45 MPH

$$
Forecaster Blake

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