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Eastern North Pacific Tropical Weather Discussion (Text)



000
AXPZ20 KNHC 111719
TWDEP 

Tropical Weather Discussion 
NWS National Hurricane Center Miami FL 
1720 UTC Mon Dec 11 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 
1530 UTC.

...SPECIAL FEATURE...

Gulf of Tehuantepec Gale Warning: A very tight pressure gradient
is sustained across the Isthmus of Tehuantepec by 1031 mb high
pres centered just west of Tampico Mexico. This pressure
gradient will maintain a swath of 30 to 45 kt gale force winds 
today, with corresponding seas in the 12-20 ft range. Fresh to
strong NE-E winds extend downstream from the gulf to near 10N and
100W, where seas run 8-11 ft primarily in NE swell. Seas 8 ft or
greater are propagating well away from the Gulf to near 110W.
Gales of 30 to 40 kt are forecast to continue over the Gulf of 
Tehuantepec tonight through Wednesday night, then abruptly subside 
to below 20 kt by midday Thu.

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

The Monsoon Trough axis extends from east Panama at 08N78W to 
05N91W. The ITCZ continues from 05N91W to 10N117W. A surface trough 
extends in a break in the ITCZ from 21N113W to 10N113W. The itcz 
resumes from 11N123W to beyond 08N140w. Scattered moderate and 
isolated strong convection are within 180 nm E of the surface trough 
axis. Scattered moderate convection is from 06N to 10N between 101W 
and 108W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Gulf of Tehuantepec: Please see Special Features section above
for details the ongoing storm event.

High pressure over the Great Basin has weakened enough to allow
fresh to strong northerly winds over the northern Gulf of
California to subside. N to NE winds funneling through the Baja
California peninsula into the Pacific waters have diminished to
light and variable. High pres ridging to the NW will maintain
gentle to moderate winds and 4-6 ft seas will persist through Thu
night.

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

Gulf of Papagayo: Strong high pres ridging SSE over
Central America and the SW Caribbean Sea has induced N to NE
winds of 20 to 30 kt over the Gulf of Papagayo and also over
an area from 06.5N to 11N between 85.5W and 90W. The pressure 
gradient will continue to loosen through tonight with strong NE 
winds being confined within a 90 nm wide swath from the Gulf to near 
09N89W by Tuesday morning. Seas of 8 to 10 ft will propagate to the 
SW well away from the fetch area through today, reaching from 05N to 
11N between 86W and 91W by this evening. The area of seas 8 ft or 
greater will begin to diminish on Tuesday as winds subside and the 
swell decays.

Strong high pressure ridging southeastward over Central America
and the NW Caribbean is generating strong to near gale force NE winds
over the Gulf of Papagayo and nearby waters. Large NE swell from
a Tehuantepec gap wind event will spread across the offshore
waters of Guatemala and El Salvador through Mon. Localized gap
pulses of strong NE winds are expected off the coast of El
Salvador and Guatemala, including Gulf of Fonseca through early this
afternoon.

REMAINDER OF THE AREA...

A stationary front crosses the NW corner of the area from 30N136W to
26N140W. Seas will run 8-14 ft in NW swell over the far NW corner 
near 30N140W and will merge with swell to the south through today, 
with long period NW swell maintaining seas of 8-11 ft W of a line 
from 30N125W to 14N126W to 08N140W on Tuesday. The swell will 
gradually decay through Wed morning. The pressure difference between 
the tropics along 10N and the high pressure over the northern waters 
is forecast to result in fresh NE to E winds S of 20N, and to the W 
of 129W.

This area of fresh winds will shift W of 130W by Tuesday afternoon 
and will persist through Tuesday night.

$$
Latto

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Page last modified: Monday, 11-Dec-2017 17:19:54 UTC