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000
AXPZ20 KNHC 290930
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Thu Sep 29 2016

Tropical weather discussion for the eastern Pacific Ocean from
the Equator to 32N, east of 140W. The following information is
based on satellite imagery, weather observations, radar, and
meteorological analysis.

Based on 0600 UTC surface analysis and satellite imagery through
0930 UTC.

...SPECIAL FEATURES...

Tropical Storm Ulika is centered at 16.0N 139.1W, or about 1080
sm e of Hilo Hawaii at 09 UTC Sep 29, moving nnw, or 340 degrees
at 5 kt. The estimated minimum central pressure is 1001 mb. The
maximum sustained wind speed is 45 kt with gusts to 55 kt.
Currently, scattered moderate to strong convection is observed
within 60 nm either side of a line from 16.5N137W to 15.5N139.5W.
Ulika is experiencing wind shear and is forecast to weaken to a
tropical depression today and further weaken to a remnant low w
of 140W within 36 hours. Refer to the latest NHC forecast/
advisory under AWIPS/WMO headers WTPZ24KNHC/TCMEP4, or visit the
NHC website at http://hurricanes.gov for additional details.
After the center moves w of 140W, refer to the latest CPHC
forecast/advisory under AWIPS/WMO headers WTPA22 PHFO/TCMCP2, or
visit the CPHC website at http:www.prh.noaa.gov/cphc/ for
additional details.

Tropical Depression Roslyn is centered at 22.7N 115.3W, or about
345 sm w of the southern tip of the Baja California Peninsula at
09 UTC Sep 29, moving nnw, or 345 degrees at 6 kt, and currently
lacks convection. The estimated minimum central pressure is 1008
mb. Maximum sustained wind speed is 25 kt with gusts to 35 kt.
Roslyn is forecast to a remnant low within 24 hours. Refer to
the latest NHC forecast/advisory under AWIPS/WMO headers WTPZ23
KNHC/TCMEP3, or visit the NHC website at http://hurricanes.gov
for additional details.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

The monsoon trough extends nw off the Pacific coast of Costa
Rica at 10N85W to 11N101W to 09N120W to 14N134W. Scattered moderate
isolated strong convection is observed within 60 nm of 10.5N87W,
within 75 nm either side of a line from 09N104W to 10N113W to
08N123W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Tropical Depression Roslyn is weakening over the far offshore
waters with winds and seas forecast below 20 kt and 8 ft later
today. A sub-tropical ridge axis extends from nw to se across
the offshore zones w of the Baja Peninsula terminating near
23N110W. Light to gentle n winds observed w of the Baja
Peninsula are expected to become a moderate to fresh nw flow,
with 5 to 8 ft seas, w of the northern half of the Baja
Peninsula on Sun.

A weak surface trough analyzed from 12N104W to 20N107W will
drift w over the next day or so. Isolated moderate and strong
convection is currently noted within 120 nm either side of a
line from 13N93W to 19N109W. Scattered moderate and strong
convection is noted within 60 nm of 22N106W.

Light and variable winds expected through the weekend across the
northern Gulf of California, and light to gentle nw-n flow is
expected elsewhere.

Fresh to strong drainage flow expected to develop across the
Gulf of Tehuantepec tonight and continue through late Fri
morning, then develop again on Fri and Sat nights.

OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND
WITHIN 750 NM OF ECUADOR...

Light to gentle southerly winds are expected n of the monsoon
trough, while gentle to locally moderate s to sw flow is
expected s of the monsoon trough through the upcoming weekend.
Combined seas of 4 to 7 ft, primarily in long-period sw swell is
expected across the offshore waters through the upcoming weekend.

REMAINDER OF THE AREA...

As tropical cyclone Ulika moves w of 140W tonight and tropical
cyclone Roslyn dissipates, the pressure gradient will tighten
around the subtropical ridge, with moderate to fresh
anticyclonic winds expected between the monsoon trough/ITCZ and
the ridge through early next week, with combined seas of 5 to 7
ft. The gradient will then relax some by the middle of next week.

$$
Nelson

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