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Eastern North Pacific Tropical Weather Discussion (Text)



000
AXPZ20 KNHC 161605
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1408 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 1200 UTC surface analysis and satellite imagery through
1430 UTC.

...SPECIAL FEATURES...

Gulf of Tehuantepec Gale Warning: A nearly stationary front 
crosses the western Gulf of Mexico from the central Bay of 
Campeche to just east of the Chivela Pass. The front has begun to
dissipate as high pressure to the west of the front over eastern
Mexico weakens. The front will then begin to drift northward this 
afternoon. This will allow winds funneling over the Gulf of 
Tehuantepec to diminish with gales expected to end this morning.
Winds over the Gulf of Tehuantepec will continue to decrease. A
regime of winds pulsing to strong speeds at night will set up
from Sun night through Wed night. 

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

The ITCZ extends from 08N81W to 08N84W to 06N93W to 10N130W to 
beyond 10N140W. Scattered moderate and isolated strong 
convection is present from 07N to 09N between 96W and 100W as 
well as from 07N to 10N between 107W and 111W. Scattered moderate
convection is observed from 12N to 15N between 134W and 139W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Gulf of California: A cold front is moving SE through Southern 
California and the offshore Pacific waters. The front is passing 
Los Angel's and will enter the northern Gulf of California 
tonight, then continue SE and dissipate over the central Gulf on 
Sun. Winds over the northern Gulf will veer from the 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 tonight will be the likelihood 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 strong gusty winds
funneling through low lying areas of Baja California Norte 
through early Sun. Winds will diminish through early next week 
after the low pressure weakens and the front dissipates. By 
weeks end, a stronger cold front sweeping across the region will
force strong to near gale force winds down the length of the 
Gulf and cause large seas to develop.

This same cold front will move through the waters off Baja 
California Norte through this morning followed by strong NW to N
winds and seas building to 8 to 14 ft late today. Seas will build
to as high as 16 ft in NW swell near new on Sunday morning. 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 seas 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 Chihuahua and
Durango in Mexico SW to the tropics near 10N115W. This has
induced a surface trough SSW of Cabo Corrientes from 16N105W to 
14N111W. Scattered moderate to isolated strong convection is 
active within 30 nm either side of a line from 19N104W to 
15N110W. 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 the 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 trade winds prevail from 14N to 25N west of 
136W. Moderate to fresh winds prevail 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 10 to 12 
ft in the area of strong trades W of 136W. 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. 

$$
CAM

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Page last modified: Saturday, 16-Dec-2017 16:05:27 UTC