Eastern North Pacific Tropical Weather Discussion (Text)

AXPZ20 KNHC 051605 RRA

Tropical Weather Discussion 
NWS National Hurricane Center Miami FL
1605 UTC Mon Dec 05 2016

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
1545 UTC.


The Monsoon Trough axis extends from 09N107W to 08N116W to
08N122W where scatterometer winds indicate the ITCZ begins and
extends to 08N131W to beyond 09N140W. Scattered moderate
convection is seen within 120 nm north of the ITCZ between 124W
and 130W, within 60 nm north of the trough between 112W and
115W, and within 30 nm of the ITCZ between 132W and 138W.

Scattered moderate convection is noted from 03N to 07N between
77W and 79W.



Gulf of California: Gentle se flow north of 29N this morning
will increase to a moderate breeze this afternoon from a
tightening of the pressure gradient between high pressure
ridging west of Baja California and the climatological low
pressure over the the far northern portion of the gulf. These
winds are forecast to change little through Tuesday night.
The next cold front is expected to move southeast across the
northern gulf waters on Wednesday followed by fresh to locally
strong northwest flow Wednesday night into Thursday. Light and
variable winds are forecast across the gulf waters south of 29N
through Wednesday, then becoming a strong northwest breeze
behind the cold front Wednesday night into Thursday. Seas are 
expected to build to 5 to 7 ft with these winds.

Gentle to moderate northerly winds are occurring to the west of
105W, with seas of 4 to 6 ft in northwest swell, except for
higher lingering seas of 6 to 8 ft north of 19N. These seas will
subside to 5 to 7 ft by Tuesday afternoon, with seas of 8 to 9
ft in decaying northwest swell continuing north of about 26N. 

A surface trough is analyzed from 17N101W to 13N102W to 10N104W.
This trough is underneath a very pronounced and active sub-
tropical jet stream branch that stretches from the deep central
tropical Pacific northeastward to over the central portion of
Mexico. Waves of upper level energy are riding along this jet
stream branch, and are helping to initiate clusters of
convection along and near the trough. Latest satellite imagery
shows scattered moderate convection within 30 nm of the trough
from 14N to 16N, and within 30 nm of 10N104W. This activity is
moving to the northeast near 15 kt. The trough is forecast to
gradually translate eastward while becoming less defined during
the next 48 hours. 

Gulf of Tehuantepec: The next surge of strong northerly winds is
expected to infiltrate the gulf late Thursday afternoon, and
gradually strengthen to minimal gale force late Thursdaty night
as strong high pressure ridges southward along the Sierra Madre
Oriental mountains along eastern Mexico. These gale conditions
will continue well beyond the discussion time frame through
early on Sunday. Combined seas are expected to build to about 20
ft downstream of the Gulf of Tehuantepec near 14.5N95.5W on


Gulf of Papagayo: Moderate to locally fresh nocturnal ene winds
are expected to begin again late Tue night with a strong
drainage event expected on Friday night. 

light to gentle northerly winds, except for light and variable
winds to the east of 97W are present elsewhere north of the
monsoon trough, with seas in the 4 to 6 ft range. A gentle to
moderate southwest flow is observed to the south of the monsoon
trough, with seas in the 5 to 6 ft in long-period southwest


A high pressure center of 1025 mb at 35N136W extends a ridge
southeastward to 32N134W to 24N123W to near 17N114W. High
pressure covers the area north of 17N west of 114W. The pressure
gradient between the high and lower pressure near the monsoon
trough is producing fresh northeast to east trade winds from 10N
to 24N west of 135W, and from 10N to 17N between 116W and 135W
with combined seas 8 to 10 ft primarily in a northwest swell.
The 1025 mb high is forecast to shift east-southeast to near
33N130W by early on Tuesday as low pressure system and its
associated frontal system well west of the discussion area
tracks to the north-northeast. With this taking place, the
current pressure gradient responsible for the aforementioned
fresh northeast to east winds will weaken allowing for these
winds to become mostly moderate east trades with locally fresh
winds on Tuesday. The 8 to 10 ft combined seas will continue on
the subsiding trend through Wednesday as the northerly swell
energy dissipates. Only a small area of 8 to 9 ft seas is
forecast to remain in the far northeast section of the area west
of northern Baja California Norte by Wednesday.


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Page last modified: Monday, 05-Dec-2016 16:05:30 UTC