Tropical Weather Discussion
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349
AXPZ20 KNHC 241500
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1500 UTC Sun Sep 24 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
1400 UTC.

...SPECIAL FEATURES...

Tropical Storm Pilar is centered near 19.9N 105.9W or about
30 nm SSW of Cabo Corrientes, Mexico and about 100 nm SSE of Las
Islas Marias, Mexico at 1500 UTC moving NNW at 7 KT. Maximum
sustained winds 40 kt gusts 50 kt. Scattered moderate and
isolated strong convection is within 120 nm of the coast of
Mexico from 18.5N to 22.5N. Heavy rainfall causing flash floods
and mudslides will be possible for Mexican states from Michoacan,
Colima, Jalisco and Nayarit, and southern Sinaloa through Monday
night. Pilar is expected to slowly track toward the NNW then N
through Tuesday night. Pilar will gradually weaken, becoming a
tropical depression by Monday evening, then dissipating by
Wednesday morning. See the latest NHC Forecast/ Advisory under
AWIPS/WMO headers MIATCMEP3/WTNT23 KNHC for more details.

..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

The monsoon trough extends from 14N109W to 12N115W to 14N123W to
low pressure near 13N125.5W to 11N131W to low pressure near
12N140W. Scattered moderate and isolated strong convection is
within 75 nm S of the axis between 109W and 117W.

Scattered moderate and isolated strong convection is also within
120-180 nm of the coast of Central America E of 90W, from 11N to
15.5N between 92W and 97W, and from 10N to 13N between 98W and
105W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

A high pressure ridge building in north of 25N will aid in
freshening NW winds west of Baja California Norte today and
tonight. Elsewhere, expect increasing winds and seas spreading
northwestward from near Cabo Corrientes to the southern Gulf of
California as Tropical Storm Pilar slowly tracks NNW during the
next few days.

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
in coastal waters the next few days. Expect moderate SW to W
winds to prevail south of the trough through Tuesday night.
Farther south, gentle to moderate south to southwest winds will
persist south of 05N through Tuesday night. Long period southerly
swell will decay and allow seas west of Ecuador and south of the
Equator to subside from around 7 ft to around 6 ft during the
next couple of days.

REMAINDER OF THE AREA...

NW swell generated by strong winds north of the area are
producing 6 to 8 ft seas N of 27N between 122W and 132W. Seas in
the area will continue to subside as the NW swell decay. Fresh to
strong winds around low pres embedded in the monsoon trough near
13N125.5W is supporting a surrounding area of 8 to 11 ft seas in
mixed swell. Scattered moderate and isolated strong convection is
within 90 nm in the SE semicircle of the low. The low will drift
to the ENE during the next few days. Otherwise, high pres
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 during
the second half of the week.

$$
Lewitsky




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