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Hurricane NORBERT


800 PM PDT FRI SEP 05 2014

The satellite presentation of Norbert has improved dramatically
since the last advisory. A ragged eye is apparent in infrared
imagery surrounded by a ring of cloud tops colder than -70C. Dvorak
estimates from TAFB and SAB at 00Z were T5.5/102 kt, and the initial
intensity is set a bit below that value at 95 kt for this advisory
given the very rapid change in the satellite appearance and the
earlier recon data. This recent intensification occurred as Norbert
moved over waters warmer than 29C, and some additional strengthening
is still possible in the next few hours. However, SSTs steadily
decrease along the track going forward, which should result in
gradual weakening beginning by 12 hours. Steadier weakening is
expected beyond 24 hours as SSTs fall below 26C and the cyclone
moves into a drier and more stable airmass. By 72 hours Norbert is
expected to become post-tropical and then weaken to a remnant low
around day 4. The new NHC intensity forecast has been adjusted
upward by 10-15 kt through 24 hours to account for the current
intensity trend, and is about 5 kt higher than the previous advisory
after that time. This forecast is a little above the intensity
consensus through 36 hours and close to the consensus afterward.

Smoothing through some short-term wobbles, the initial motion
estimate is 320/08. The track forecast reasoning remains unchanged,
as Norbert will be steered around the western periphery of a mid-
level ridge centered over the southern United States through 48
hours. After that time, the ridge weakens as a mid-latitude trough
moves into the U.S. West Coast. This should result in a weakening of
the steering currents, leaving the low-level center of Norbert to
drift slowly northward or move erratically at the end of the
forecast period. The new NHC track forecast is similar to the
previous one, but has been adjusted a little to the east to account
for the initial position and motion. This track is close to the
TVCE multi-model consensus through 72 hours, and shows little net
motion after that time.

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.


INIT  06/0300Z 24.2N 112.8W   95 KT 110 MPH
 12H  06/1200Z 24.9N 113.8W   90 KT 105 MPH
 24H  07/0000Z 25.6N 114.9W   80 KT  90 MPH
 36H  07/1200Z 26.5N 116.1W   65 KT  75 MPH
 48H  08/0000Z 27.3N 117.0W   50 KT  60 MPH
 72H  09/0000Z 29.0N 117.5W   35 KT  40 MPH...POST-TROPICAL
 96H  10/0000Z 29.5N 117.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  11/0000Z 29.5N 117.5W   20 KT  25 MPH...POST-TROP/REMNT LOW

Forecaster Brennan