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Eastern North Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 160938
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Sat Dec 16 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 
0830 UTC.

...SPECIAL FEATURES...

Gulf of Tehuantepec Gale Warning: A cold front has stalled across 
the western Gulf of Mexico this morning and is extends across 
the central Bay of Campeche and through the Chivelas Pass. 
Recent ASCAT data prior to 0400 UTC showed northerly winds to 
around 30 kt across the Gulf of Tehuantepec northward of 15.5N. 
Winds are assumed to have increased to gale force over the Gulf 
of Tehuantepec since this time. The cold front will weaken 
during the day Saturday, and begin to drift northward by 
afternoon. This will diminish winds funneling across the Gulf of 
Tehuantepec with gales expected to end by late morning, or 
around 1500 UTC, then continue to gradually diminish during the 
afternoon.  

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

A weak trough extends from the Gulf of Panama westward to 90W. 
The ITCZ extends from 06.5N91W to beyond 10N140W. Scattered 
moderate to strong convection is noted within 120 nm N of the 
ITCZ between 96W and 99W, and from 110W to 113W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Gulf of California: A cold front is moving SSE into Southern 
California and the offshore Pacific waters tonight and will move 
into the northern Gulf of California today, before stalling and 
dissipating over the central Gulf on Sun. Winds over the 
northern Gulf will shift SW early today ahead of the front, and 
increase to strong by afternoon as associated low pressure 
deepens over the lower Colorado River basin. The main issue by 
Sat night will be the possibility of strong W to NW winds over 
the northern Gulf as the low pressure shifts eastward into the 
Sonora Desert. While the fetch across the northern Gulf will be 
too limited to develop large seas, mariners should be aware of 
the possibility of sudden strong winds through low lying areas 
of Baja California Norte through early Sun. Winds diminish 
through early next week after the low pressure dissipates. By 
weeks end, another cold front sweeping across the region will 
force strong to near gale force winds spreading the length of 
the Gulf, with large seas developing.

This same cold front will move through the waters off Baja 
California Norte through this morning followed by strong NW 
winds and seas building to 8 to 12 ft late today. Seas of 8 to 
10 ft will cover most of the waters beyond 60 nm of the Baja 
coast through early next week in NW swell. Elsewhere gentle to 
moderate winds and 3 to 5 ft will persist along the coast of 
Mexico outside of the Gulf of Tehuantepec through mid week.

To the SE, and upper level trough extends from Sinaloa SW to the 
tropics near 11N120W. A broad low level convergence zone extends 
from near 10N120W to the coast of Mexico between Cabo Corrientes 
and Manzanillo, where scattered moderate to strong convection is 
active tonight under strong upper level SW winds occurring to 
the SE of the upper trough. Weather across this zone is expected 
to remain active today and shift slightly northward along the 
coast tonight and Sunday ahead of the front moving across Baja 
California.

Please see Special Features section for more information on the
latest Gulf of Tehuantepec gale warning. 

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

Fresh winds forecast to develop across the Gulf of Papagayo 
today are expected to strengthen to 20-25 kt tonight. Fresh N 
winds will funnel into the Gulf of Panama through late this 
morning. 

REMAINDER OF THE AREA...

Fresh to strong tradewinds prevail from 11N to 21N west of 128W.
Moderate to fresh winds prevails elsewhere over the forecast 
waters north of the ITCZ to 20N and west of 120W. Seas 
associated with a fresh pulse of NW swell are reaching 13-14 ft 
in the area of strong trades W of 135W. Seas will slowly subside 
as the swell propagates southeast the next few days. A cold 
front will move into the far northern waters Saturday. This will 
usher in another set of northerly swell into the area. 

$$

Stripling