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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 110920

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
841 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 0600 UTC surface analysis and satellite imagery through
0900 UTC.


Gulf of Tehuantepec Storm Warning: A very tight pressure gradient
is sustained across the Isthmus of Tehuantepec by 1032 mb high 
pres centered just west of Tampico Mexico. This pressure 
gradient will be augmented by nocturnal drainage flow to maintain
storm force winds of 40-50 kt over the Gulf of Tehuantepec until
around dawn on Mon, with seas in the 14-21 ft range. A swath of 
30 to 40 kt gale force winds surrounds the area of storm force 
winds within 60 nm either side of a line from 16N95W to 14N96W to
13N97W, with corresponding seas in the 12-18 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 106W 
this evening. The area seas 8 ft or higher will spread even 
farther W to near 110W on Monday. Gales are forecast to continue 
over the Gulf of Tehuantepec through Wednesday night, then 
abruptly subside to below 20 kt by noon on Thu.

Gulf of Papagayo Gale Warning: Strong high pres ridging SSE over
Central America and the SW Caribbean Sea has induced NE gale 
force winds of 30 to 35 kt over the Gulf of Papagayo. N to NE 
winds of 20 to 30 kt are occurring elsewhere downstream from the 
gale force winds over an area from 06.5N to 11N between 85.5W 
and 90W. The pressure gradient will loosen enough to allow for 
these gale conditions to diminish to strong to near gale force NE
winds late Monday morning and then to strong NE winds Tuesday 
evening. Seas of 8 to 10 ft will propagate to the SW well away 
from the fetch area and reaching from 05N to 11N between 86W and 
91W by Monday evening. The area of seas 8 ft or greater will 
begin to diminish on Tuesday as winds subside and the swell 


The Monsoon Trough axis extends from east Panama at 08N78W to 
06N93W. The ITCZ continues from 06N93W to 08N114W to 11N118W. THE
itcz resumes from 09N123W to beyond 08N140w. Scattered moderate 
convection is from 07N to 09N between 104W and 107W.



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


Gulf of Papagayo: See the Special Features section above for 
details on the ongoing gale event that will last a few more

Strong high pressure ridging southeastward over Central America
and the NW Caribbean is generating strong to 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 Mon


A cold front crosses the NW corner of the area from 30N136W to 
26N140W. Strong S to SW winds ahead of the front and N of 29N 
have subsided as the front begins to weaken. Seas will run 8 to 
14 ft in NW swell N of a line from 30N133W to 21N140W. The front
will dissipate by late Monday night, however, long period NW 
swell will maintain seas of 8-11 ft W of a line from 30N126W to 
20N129W to 13N128W to 09N140W. The swell will gradually decay 
through Wed morning, with seas of 8-11 ft expected W of a line 
from 20N122W to 00N137W. The pressure difference between the
tropics along 10N and the high pressure over the northern waters
is forecast to result in strong NE to E winds beginning late 
Monday night from 13N-18N, and to the W of 129W along with seas 
of 8 to 10 ft. This area of strong winds will shift W of 130W by 
noon on Tuesday, then diminish to between 15 and 20 kt late