Tropical Weather Discussion
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000
AXPZ20 KNHC 251456
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1456 UTC Mon Sep 25 2017

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 Depression Pilar is centered near near 22.8N 107.0W, or
about 39 nm SW of Mazatlan, Mexico, or about 87 nm NNW of Las
Islas Marias, Mexico at 1500 UTC, moving NNW at 6 kt. Estimated
minimum central pressure is 1004 mb. Maximum sustained winds 30
kt with gusts to 40 kt. Scattered moderate convection is within
120 nm in the NE semicircle, 0 nm in the S quadrant and 60 nm W
quadrant. Pilar is expected to continue to slowly track toward
the NNW to N, moving along or just offshore of the coastline.
Pilar is expected to become a remnant low by this evening,
dissipating by Tuesday morning. Even so, very heavy rainfall
causing flash floods and mudslides remains possible for the
Mexican states of Nayarit, southern Sinaloa, and southwestern
Durango through Tuesday. See the latest NHC Forecast/ Advisory
under AWIPS/WMO headers MIATCMEP3/WTNT23 KNHC for more details.

..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

The monsoon trough axis extends from 10N75W to 18N86W to low
pressure near 14N92W to 16N98W to 15N115W to low pressure near
13.5N126W to 11N135W to 11N140W. Scattered moderate and isolated
strong convection is from 01N to 03N and E of 81W, within 180 nm
SW of a line from 07N86W to 09N89W to 13N90W to 16N97W, from 11N
to 13N between 99W and 106W, and also within 120-180 nm S of the
axis between 128W and 140W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Winds and seas associated with Tropical Depression Pilar will
affect the southern Gulf of California through Tuesday.

A high pressure ridge reaching SE into the waters west of Baja
California will maintain moderate NW winds along the Pacific
coast of Baja through tonight. The ridge will weaken in response
to low pressure passing well to the north and NW winds will
become gentle to moderate Tuesday through Thursday night. Fresh
SW to W monsoonal winds well offshore of the Gulf of Tehuantepec
will generate SW wind waves in the SE waters and maintain seas in
this area of 5 to 7 ft.

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

An active monsoon trough near the coast of Central America from
Guatemala to Panama will remain the focus for active convection
over the coastal waters the next few days. Expect moderate to SW
to W winds to prevail south of the trough, with gentle to
moderate offshore or variable winds north of the trough through
Friday night.

Long period SE to S swell will decay and allow seas west of
Ecuador and south of the Equator to subside from around 6 ft to
around 5 ft during the next couple of days.

REMAINDER OF THE AREA...

NW to N swell generated by strong winds north of the area are
producing 6 to 7 ft seas N of 20N and W of 120W. Sets of
reinforcing N swell will maintain seas in the region between 6
and 8 feet through Wed night.

Fresh to strong winds around low pressure embedded in the
monsoon trough near 13.5N126W are supporting a surrounding area
of 8 to 10 ft seas in mixed swell. Associated scattered moderate
and isolated strong convection is from 12N to 14.5N between 120W
and 127W. The low will shift to the ENE during the next couple
of days.

Otherwise, high pressure centered well N of the area, and low
pressure associated with the monsoon trough will maintain
moderate to occasionally fresh trade winds W of 120W through
tonight. Low pressure passing north of the area will weaken the
high, allowing trades to decrease for the remainder of the week.

$$
Lewitsky




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