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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 300936

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
539 UTC Tue Aug 30 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
0900 UTC.


Lester has begun to weaken and now is a category 3 hurricane on
the Saffir-Simpson Hurricane Wind Scale. At 30/0900 UTC, it is
centered near 18.2N 133.2W or about 1435 MI...2305 KM E of Hilo,
Hawaii, moving W or 275 degrees at 12 kt. Estimated minimum
central pressure is 956 mb. Maximum sustained winds are 110 kt
with gusts to 135 kt. Some weakening is forecast during the next
48 hours. Lester is forecast to cross 140W and move into the
central Pacific basin by Wednesday night while continuing on a
westward motion. The areal extent of deep convection has
decreased since late yesterday, and now satellite imagery shows
numerous moderate to strong convection within about 75 NM of the
center. Numerous moderate to isolated strong convection is
elsewhere within about 90 NM of center, except 120 NM SW quadrant.
See latest NHC forecast/advisory under AWIPS/WMO headers
MIATCMEP3/WTPZ23 KNHC for more details.


The monsoon trough axis extends from 10N93W to 12N110W to a 1012
mb low pressure near 11N118W to 14N125W. A cluster of moderate to
strong convection is from 05N to 08N between 86w and 88.5W. Scattered
moderate to isolated strong convection is from 10N to 14N between
86W and 100W. Similar convection is from 11N to 15N between 104W
AND 106W.



A ridge dominates the waters off Baja California. The pressure
gradient between the ridge and the persistent trough meandering
along the Baja California peninsula will result in moderate to
locally fresh northerly winds and seas generally under 6 ft across
the forecast zones off Baja California. Little change in this
weather pattern is expected through the end of the week. Marine
guidance suggests seas will build close to 8 ft in NW swell across
the western part of zone PMZ011 tonight and Wednesday, then
subside. Surface troughing over the Baja peninsula will maintain a
light and variable wind regime in the Gulf of California through
the end of the week with seas generally 2 ft or less. Farther
south, winds will be mainly gentle to moderate and WNW with
combined seas of 4 to 5 ft. Moderate northerly winds are expected
across the Gulf of Tehuantepec early this morning, then a light
and variable wind pattern is forecast across this area through


Gentle to moderate SW winds will prevail S of the monsoon trough
with mainly light to gentle winds N of it through Friday. Long
period cross equatorial SW swell will continue to dominate the
area with seas ranging between 4 and 7 ft.


A broad surface ridge covers most of the northern waters,
extending from 1022 mb high pressure near 31N132W. The tail end
of a weakening stationary front crosses the NW part of the
forecast area and extends from 30N137W to beyond 28N140W.
Scatterometer data continue depicting the wind shift associated
with this front. Scattered low-topped showers are occurring in the
vicinity of this feature. The pressure gradient between the ridge
and Lester continues to produce a band of fresh to occasionally
strong winds roughly from 20N to 25N between 128W and 135W, with
combined seas ranging from 8 to 12 feet. These marine conditions
will move westward in tandem with Lester over the next 36-48

Scatterometer data provided observations of fresh to locally
strong SW winds S of the monsoon trough and mainly from 09N to 
11.5N between 97W and 111W. Seas are 8-9 ft within this area. A
pair of weak low pressure centers along the monsoon trough appear
to be enhancing these winds.

Looking area of low pressure could form a few hundred
miles south or southwest of the south-central coast of Mexico
around the end of the week. Environmental conditions are expected
to be conducive for slow development of this system while it moves
west-northwestward or northwestward. Currently, the chance of
tropical cyclone formation is assessed to be low through 5 days.