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Eastern North Pacific Tropical Weather Discussion (Text)



000
AXPZ20 KNHC 172204
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 UTC Tue Jan 17 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 1800 UTC surface analysis and satellite imagery through 
2130 UTC.

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

A meandering trough extends from 05N77W TO 00.5N84W TO 
05.5N93.5W TO 02.5N101W. The ITCZ extends from 02.5N101W TO 
02N107W TO 08N122W TO 07N130W TO 06.5N140W. Small areas of 
scattered moderate isolated strong convection are located within 
210 nm N of the ITCZ between 113W and 130W. Scattered to locally 
numerous strong convection is occurring from 11.5N to 16N 
between 110W and 120W.

...DISCUSSION...   

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Satellite imagery shows a frontal trough across the Pacific 
offshore waters west of Baja California extending from 23N113W 
to 27N120W drifting southward. A supporting upper level trough 
extends from a deep layered cut off low along the Arizona-New 
Mexico border SW to beyond 22N126W. An upper level jetstream is 
moving through the base of this trough and into central Mexico, 
and transporting an upper level moisture plume. Strong low level 
convergence is occurring in a broad zone about 200 nm wide from 
offshore of Cabo Corrientes near 20N107W to near 13N121W. 
scattered to numerous convection described above is occurring 
within this zone and being enhanced by the jetstream energy 
aloft, with lighter elevated convection likely moving NE and 
inland across western Mexico and Sierra Madres between 
Manzanillo and Mazatlan. Gentle to moderate mainly northwest 
winds prevail off the coast of Baja California and in the Gulf 
of California. Light to gentle northerly winds prevail south and 
east of Acapulco. Seas across the area are running 5-6 ft west 
of Baja California, 2 ft or less in the Gulf of California, and 
2-5 ft elsewhere. 

Global models indicate a cold front will move into the waters 
off Baja California Norte Thursday, then become diffuse ahead of 
a much stronger cold front that will quickly move in across Baja 
California and the Gulf of California Friday and Saturday. The 
second front will be accompanied by fresh to strong winds and 
large northwest swell. This swell is expected to build seas to 
12-19 ft over the waters off Baja California Norte Saturday, and 
8-13 ft seas off Baja California Sur. This will bring hazardous 
surf conditions to mariners navigating the nearshore and 
coastal waters.

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

Moderate northwest winds will pulse to 25 kt late tonight and 
again late Wednesday night across the Gulf of Papagayo and 
downwind to about 89W, then diminish by Thursday night. Light to 
gentle variable winds are expected there Friday.

Light to gentle easterly winds will prevail elsewhere through 
Saturday. Seas will be generally 3-5 ft in the forecast waters.

REMAINDER OF THE AREA...

1024 mb high pressure centered near 28N134W extends a ridge 
southeast to the Revillagigedo Islands. The gradient between 
this high and lower pressure associated with the ITCZ is 
supporting an area of fresh to strong northeast trade winds from 
10N TO 15N W OF 129W, with 9-11 ft seas. Fresh trades are found 
elsewhere from 11N TO 14N BETWEEN 121W AND 129W, with seas to 10 
ft in mixed northwest swell and northeast wind waves. The zone 
of strongest trade winds will decrease in coverage and shift 
westward during the next couple of days. Fresh trades will 
remain from 07N to 20N west of 122W, with 8-10 ft seas in mixed 
northeast waves and northwest swell.

As mentioned above, a very active jet stream branch is rounding 
the base of the deep layered trough across northwest Mexico. The 
upper trough will move eastward during the next couple of days 
as high pressure builds eastward behind the previously mentioned 
cold fronts, with associated moisture and weather shifting 
eastward with it.

Looking ahead, northwest swell with seas to 8-12 ft associated 
with a cold front moving eastward across the waters north of 25N 
Wednesday and Thursday will be followed by a second front 
expected to sweep southeastward into northern waters Thursday 
night and Friday. Wave model guidance shows large northwest 
swell will propagate southeastward into the waters north of 20N 
behind the second front, with seas building to 15-20 ft in the 
far northern waters east of 130W late Friday into Saturday. 

$$
Stripling


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Page last modified: Tuesday, 17-Jan-2017 22:04:20 UTC