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000
AXPZ20 KNHC 302157
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2105 UTC Fri Sep 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 1800 UTC surface analysis and satellite imagery through
2145 UTC.

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

The monsoon trough axis extends from 09N85W to 10N91W to 11N99W
to 11N104W. It resumes at 13N113W to 10N122W to 08N127W to
low pressure near 12N135W 1012 mb to 12N140W. Scattered moderate
isolated strong convection is within 180 nm south of the axis
between 85W and 88W. Scattered moderate convection is within
180 nm south of the axis between 103W and 107W, and also within
60 nm of the axis between 90W and 95W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

The weakening remnant low of Roslyn is centered near 24N117W with
a pressure of 1015 mb. Latest satellite imagery depicts it as a
low-level cloud swirl from 22N to 25N between 116W and 119W. It
will dissipate by early Saturday afternoon.

A weak pressure gradient over the forecast waters is supporting
mainly light to gentle winds across the area. Earlier strong north
winds that funneled through the Gulf of Tehuantepec during the
overnight and early morning hours have diminished to moderate
intensity. The resultant seas of 8 to 10 ft have subsided to 6 to
7 ft. However, the respite will be short-lived as the pressure
gradient between high pressure ridging over central Mexico and
surface trough over the eastern Bay of Campeche again tightens
tonight. This will send another surge of strong north winds the
isthmus of Tehuantepec and through the Gulf late tonight, and into
Saturday morning with seas building to the range of 8 to 10 ft.

Seas are in the 4 to 6 ft range north of 20N outside the Gulf of
California, 6 to ft south of 20N, and 2 ft or less through all
but the southern entrance to the Gulf of California. As the
remnant low of Rosyln dissipates, high pressure will build across
the region from the northwest through the weekend and strengthen
the pressure gradient to the west of 110W. This will produce a
modest increase in winds across the Pacific waters of the Baja
California Peninsula. Associated northwest to north swell is
forecast by wavewatch model guidance to spread into the northeast
waters beginning early on Saturday with seas of 6 to 8 ft. The
swell is expected to reach further south to near 26N by Sunday
afternoon with seas building to around 9 or 10 ft.

A surface trough is analyzed from 22N113W to low pressure near
17N113.5W to 13N113W. Scattered moderate to strong convection is
occurring within 120 nm west of the trough and from 17N to 19N,
and within 30 nm of a line from 18N110W to 19N111W. Scattered
moderate convection is within 45 nm of 17N111W, and within 30 nm
of a line from 15.5N113.5W to 13N114W. The trough will continue
to move west-northwest through Sunday with low chances for
development.

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

Light and variable winds are expected north of the monsoon
trough, while gentle to locally moderate south to southwesterly
winds are expected south of the monsoon trough through the
upcoming weekend. Combined seas of 4 to 7 ft, primarily in long-
period southwesterly swell is expected across the offshore waters
through the upcoming weekend.

REMAINDER OF THE AREA...

High pressure will build over the northern waters which will
increase the pressure gradient, freshening winds north of the
monsoon trough this weekend. The long fetch of these fresh trades
will help build seas to the 7-9 ft range early next week.

$$
AGUIRRE

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