Hurricane NORBERT

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HURRICANE NORBERT DISCUSSION NUMBER  10
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP142014
200 PM PDT THU SEP 04 2014

Norbert has changed little on satellite images today, with the
central dense overcast remaining fairly solid, and only faint hints
of an eye.  An Air Force Reserve Hurricane Hunter Aircraft found
maximum 700 mb winds of 84 kt, with peak SFMR values of 78 kt. These
data support an initial intensity of 80 kt for this advisory, which
happen to correspond well to a blend of all the currently available
Dvorak estimates.

The hurricane is probably near its peak intensity since it will soon
move over somewhat cooler SSTs and become more influenced by drier
stable air from the subtropical eastern Pacific waters.  Model
guidance is in fairly good agreement on the cyclone gradually losing
strength over the next few days, and little change has been made to
the previous forecast, which remains close to the model consensus.
The cyclone is expected to transition into a remnant low in about 4
days when it moves over waters cooler than 24C.

Norbert is moving northwestward at about 7 kt. A mid-level ridge is
expected to persist over northwestern Mexico, keeping Norbert on the
same general course during the next few days.  Model guidance has
shifted a bit closer to the southern Baja California peninsula
during the first couple of days, but all of the guidance keeps the
center a relatively safe distance offshore.  Thereafter, the key to
the long range forecast appears to be how much ridging rebuilds in
over northwestern Mexico in the wake of a weak shortwave.  The ECMWF
and the UKMET have a stronger ridge, which keeps Norbert, or its
remnants, farther offshore of southern California. The GFS-based
guidance moves Norbert closer to northwestern Mexico or southern
California, mostly due to a weaker ridge.  The dynamical model
consensus has changed little during the past few cycles, so I have
elected to keep the previous forecast almost the same at days 4-5,
which is just a bit south of the latest consensus aids.

Moisture from the remnants of Dolly and the Pacific ITCZ is being
advected northward by the outer circulation of Norbert across
northern Mexico and into the southwestern United States. This could
result in heavy rains and life-threatening flash flooding in these
areas during the next few days.  Please see information from your
local weather office for more details.


FORECAST POSITIONS AND MAX WINDS

INIT  04/2100Z 21.2N 110.8W   80 KT  90 MPH
 12H  05/0600Z 22.0N 111.5W   80 KT  90 MPH
 24H  05/1800Z 23.0N 112.5W   75 KT  85 MPH
 36H  06/0600Z 23.9N 113.5W   70 KT  80 MPH
 48H  06/1800Z 24.8N 114.7W   60 KT  70 MPH
 72H  07/1800Z 26.4N 117.0W   45 KT  50 MPH
 96H  08/1800Z 28.1N 118.5W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  09/1800Z 29.0N 119.0W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Blake

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