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Eastern North Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 261558
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1605 UTC Mon Sep 26 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 1200 UTC surface analysis and satellite imagery through
1500 UTC.

...SPECIAL FEATURES...

Tropical Storm Roslyn is centered near 17.0N 119.4W at 26/1500Z,
or about 645 nm WSW of the southern tip of the Baja California
Peninsula, moving NNE or 015 degrees at 4 kt. A turn toward the
northeast with some increase in forward speed is expected later
today. Estimated minimum central pressure is 1005 mb. Maximum
sustained wind speed is 35 kt with gusts to 45 kt. Little change
in strength is forecast during the next day or so. Weakening
should begin by Tuesday night. Currently, a cluster of moderate to
isolated strong convection is within about 180 nm E semicircle of
center. Scattered moderate isolated strong is elsewhere in a band
within 90 nm SE of a line from 16N118W to 14N119W to 13N121W. On
the forecast track, Roslyn is expected to remain west of the
offshore forecast zones. It is forecast to maintain minimum
tropical storm strength through Tue morning, then lose tropical
characteristics and become a remnant low by Wednesday morning near
21.0N 117.2W at 28/1200 UTC. Please, 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.

A new tropical depression has formed near 140W. T.D.Nineteen-E is 
centered near 11.6N 139.6W at 26/1500Z, or about 1015 nm ESE of HILO
Hawaii, moving NW or 305 degrees at 4 kt. A turn toward the north is 
expected today, followed by a turn toward the north-northeast on
Tuesday, with the center remaining E of 140W through Thursday.
Estimated minimum central pressure is 1005 mb. Maximum sustained
wind speed is 30 kt with gusts to 40 kt. A custer of moderate to
isolated strong convection is within about 60 nm NE semicircle. 
Scattered moderate to isolated strong convection is elsewhere from 
09N to 13N W of 137W. T.D.Nineteen-E is forecast to gradual
strengthen during the next couple of days. The intensity forecast
shows this tropical cyclone reaching tropical storm force at
27/0000 UTC. Please, 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.

...TROPICAL WAVE...

A tropical wave previously located near 99W is no longer
discernible on 700 mb streamlines analysis and surface data.
Instead, a surface trough is analyzed across the Gulf of
Tehuantepec from 08N95W to 16N94.5W. A 5-day TPW loop and 700 mb
streamlines analysis indicate abundant moisture between 93W-101W
with a trough persisting across the Gulf of tehuantepec region.

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

The monsoon trough extends across the far SW Caribbean and central
Costa Rica into the EPAC near 09N85W to 12N95W to 09N110W, then
it resumes just SW of Roslyn near 12N123W, and continues to
12N134W to T.D. Nineteen near 11.5N 139.5W. Scattered moderate
convection is noted from 05N-07N between 96W-91W...and from 07N-
09N between 94-99W.


...DISCUSSION...   

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

A sub-tropical ridge axis extends from NW to SE across the
offshore zones W of the Baja California Peninsula to near
24N117W. Light to gentle NW winds are observed W of the Baja
California Peninsula. Gentle to occasionally moderate flow
expected elsewhere along the Pacific coast of Mexico through
tonight. Moderate to fresh winds on the eastern side of tropical
cyclone Roslyn are expected to affect the extreme western waters
of offshore zones PMZ015 and PMZ013 from Tue night through
Thursday morning.

Building high pressure over the Great Basin to the north of the
region will allow a brief surge of fresh northerly winds across
the northern Gulf of California through late Tuesday morning.

A cold front is forecast to move across the Gulf of Mexico
waters tonight followed by a stronger cold front on Thursday.
High pressure behind the fronts will likely induce the first Gulf
of Tehuantepec gap wind event of the season by Wednesday night
into Thursday morning. Marine guidance suggests Northerly winds of
20-30 kt with seas up to 9-10 ft by Thursday.

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

Mainly light and variable winds are noted north of the monsoon
trough while gentle to locally moderate south to southwest flow
is expected south of monsoon trough the middle of the week. Combined
seas of 3-6 ft, primarily in long-period southwest swell, are
expected through the middle of the week.

REMAINDER OF THE AREA... 

A 1024 mb high pressure located near 35N139W extends a ridge
across the north waters, particularly N of 20N. Between 10N-20N W
of 110W there are two tropical cyclones. Please, see special
features for details.

$$
GR