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000
AXPZ20 KNHC 252200
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 UTC Thu Aug 25 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 1800 UTC surface analysis and satellite imagery through
2145 UTC.

...SPECIAL FEATURES...

Tropical Storm Lester is centered near 16.9N 113.4W at 2100 UTC
or about 408 nm to the south-southwest of the southern tip of
Baja California. Lester is moving WNW or 295 deg at 9 kt with
maximum sustained winds having increased slightly from this
morning to 50 kt with gusts to 60 kt. The estimated minimum
central pressure is 1000 mb. During the course of the day Lester
showed some organization to its overall cloud pattern. Satellite
imagery shows numerous strong convection within 45 nm of the
center in the southwest quadrant. Scattered convection is
elsewhere within 90 nm of the center in the southwest
semicircle, and within 60 nm of the center in the northeast
semicircle. Lester is forecast to continue moving west-northwest
and away from the Mexican offshore waters tonight as it
gradually strengthens to a hurricane near 18N115W by early
Friday afternoon. Please read the NHC forecast/advisory under
AWIPS/WMO headers MIATCMEP3/WTPZ23 KNHC or the public bulletin
under MIATCPEP3/ WTPZ33 KNHC for more details.

A broad tropical wave is moving along the monsoon trough in the
vicinity of 129W-131W, moving westward near 15 knots. A 1008 mb
low pressure center is suggested near 11.5N129W. Scattered to
numerous strong convection has developed in recent hours within
360 nm across the NW semicircle, while scattered moderate to
strong convection was elsewhere along the monsoon trough within
120 nm of the center. Fresh NE trade winds cover the area from
13N to 19N from 124W westward, where seas are running 6-9 ft.
Environmental conditions are conducive for continued gradual
improvement in organization of this system. It has a medium
chance for tropical cyclone development during the next 48
hours before crossing 140W by 72 hrs.

...TROPICAL WAVES...

No additional waves at this time.

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

The monsoon trough axis extends from 10N85W to 10N90W to 09N96W
to 10N108W. It resumes at 14N120W to low pressure at 11.5N132W
1008 mb to beyond 10N140W. Scattered moderate isolated strong
strong convection is within 120 nm south of the axis between 93W
and 98W, within 120 nm south of the axis between 130W and 138W,
and within 120 nm south of the axis between 104W and 109W.
Similar activity is south of the axis from 08N to 10N between
127W and 130W.

Scattered moderate isolated strong convection is north of the
axis within 60 nm of line from 12N91W to 12N97W to 12N101W.
...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

A narrow surface ridge extends from the NE Pacific southeastward
through 30N129W to north of Lester near 21N113W. This ridge will
change little through the upcoming weekend, and combine with the
persistent trough meandering along the Baja California peninsula
and Gulf of California, to produce mainly light to moderate
northerly flow prevailing outside of the Gulf of California.
Expect mainly light to gentle southerly flow In the Gulf of
California, except for occasionally fresh wind flow in the
northern Gulf where the pressure gradient will be slightly
tighter.

High pressure in the Gulf of Mexico has weakened. The strong
gradeint associated with it earlier help usher 20-30 kt
north to northeast winds through the Gulf. This winds have
diminished to 20-25 kt this afternoon, and are forecast to
diminish to 15-20 kt by late tonight, and lower to 10-15 kt on
Friday.

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

Global models suggest that a weak surface trough will develop
just east of the Gulf of Tehuantepec tonight and help to draw
the southwesterly winds occurring south of the monsoon trough
northward into these coastal areas. A light and variable onshore
flow is thus expected to prevail through the weekend.

ELSEWHERE...

A broad surface ridge covers the remainder of the area,
extending from a large 1036 mb high near 49N145W. The low
pressure center that is along 132W will move westward during the
next few days. The pressure gradient between this lower pressure
and the ridge will yield fresh winds across the trade wind belt,
generally from 21N southward to near the trough, from just to
the northeast of the low center to beyond 140W. Sea ranging from
6 to 8 feet presently in this area in mixed swell will increase
slightly to 7 to 9 feet during this time. A large area of fresh
southwesterly monsoonal flow is supporting seas of 6 to 8 feet
from 07N northward between 115W and 125W. The strength and areal
coverage of these fresh winds will increase to the south and
southeast of the low center as it shifts westward during the
next few days.

$$
Aguirre

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