Tropical Storm NORBERT

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TROPICAL STORM NORBERT DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP142014
800 AM PDT TUE SEP 02 2014

The area of low pressure located a couple of hundred miles southwest
of Manzanillo now has enough organized convection to be considered a
tropical cyclone.  Although moderate northeasterly shear is present,
banding features are in the southern semicircle of the cyclone along
with bursts of convection near the center.  The initial wind speed
is set to 35 kt in accordance with earlier ASCAT data.

Norbert has been moving toward the north-northeast or 020/12.
Almost all of the guidance show Norbert turning sharply northward
and west-northwestward within 24 hours due to the cyclone leaving
the ITCZ and becoming steered by a mid-level high over Mexico.  The
NHC prediction during this time is on the right side of the guidance
envelope, mostly because of the initial motion.  After that time,
there is some uncertainty in the strength of the ridge over
northwestern Mexico, which causes some spread in the model tracks of
Norbert while it approaches the southern Baja California peninsula.
While the NHC forecast is close to the model consensus after 24
hours, it would not be surprising to see later forecasts be
adjusted a bit to the north at longer range, given model trends.

The environment near Norbert seems mostly favorable for
strengthening during the next few days with the cyclone forecast
over warm waters with moderate shear.  Given this environment, it
is a little surprising that none of the more reliable models makes
Norbert a hurricane.  Since there is some possibility of land
interaction and higher shear, the NHC prediction will be a little
above the model consensus, but below the highest guidance.


FORECAST POSITIONS AND MAX WINDS

INIT  02/1500Z 17.5N 106.5W   35 KT  40 MPH
 12H  03/0000Z 18.6N 107.0W   40 KT  45 MPH
 24H  03/1200Z 19.3N 108.4W   45 KT  50 MPH
 36H  04/0000Z 19.6N 109.6W   50 KT  60 MPH
 48H  04/1200Z 20.1N 110.5W   50 KT  60 MPH
 72H  05/1200Z 21.8N 112.8W   50 KT  60 MPH
 96H  06/1200Z 23.0N 115.5W   45 KT  50 MPH
120H  07/1200Z 23.5N 117.5W   40 KT  45 MPH

$$
Forecaster Blake

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