Eastern North Pacific Tropical Weather Discussion (Text)

AXPZ20 KNHC 041605 RRA

Tropical Weather Discussion 
NWS National Hurricane Center Miami FL
1605 UTC Sun Dec 04 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 northwest off the Pacific coast
of Costa Rica at 10N84W to 08N93W to 09N125W where scatterometer
winds indicate the ITCZ begins and continues to 09N134W to
09N140W. Clusters of scattered moderate to isolated strong
convection are noted within 120 nm north of the trough axis
between 118W and 125W. Scattered moderate convection is within
30nm of a line from 09N103W to 09N108W.



Gulf of California: Strong northwest winds and 5 to 7 ft seas
currently to the north of 27N will diminish/subside to a fresh
breeze this afternoon and further diminish to a moderate to
fresh breeze tonight, with the associated seas subsiding to 2 to
4 ft. Light to gentle southerly flow is expected north of 29N on
Mon, with light and variable winds forecast across the gulf
waters south of 29N. The next cold front is expected to pass
across the northern gulf on Wednesday, with fresh to locally
strong post-frontal flow forecast on Wednesday night.

Moderate to fresh northwest to north winds, with combined seas
of 5 to 8 ft, are currently observed across the Pacific waters
west of 117W. The pressure gradient will gradually slacken
through Tuesday allowing for the winds to diminish to a gentle
to moderate northerly breeze on Monday, with combined seas in
the 4 to 6 ft range, except for higher seas of 7 to 9 ft in
northwest swell north of 26N Monday and Tuesday.

A low-level trough extends along 102W from 10N to 17N. This
trough is under a very active and strong sub-tropical jet stream
branch with multiple disturbances riding southwest to northeast
along it. Small clusters of scattered moderate convection are
observed within 15 nm either side of trough. Similar convection
is present west of the trough within 30 nm either side of a line
from 11N108W to 14N105W to 16N103.5W to along the coast of
Mexico just west of Puerto Vallarta near 19N103W. The trough is
forecast to gradually shift east-southeast through the next
couple of days while weakening.

Gulf of Tehuantepec: The next strong gap wind event is expected
to begin beyond 48 hours early on Thursday afternoon. Northerly
winds across the Gulf will quickly strengthen to minimal gale
force late Thursday afternoon, with the gale conditions possibly
increasing to strong gale winds through early on Saturday. Along
with these winds, seas are forecast to rapidly build to large
heights of around 17 to 21 ft.


Gulf of Papagayo: Moderate to locally fresh nocturnal northeast
to east winds are expected to begin again late Tue 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.


Strong high pressure of 1030 mb north of the area at 36N136W
extends a ridge southeastward to 32N132W to 24N125W to near
16N115W. High pressure covers the area north of 17N and west
of 115W. The pressure gradient between the high and lower
pressure near the monsoon trough is producing fresh northeast to
east trade winds from 10N to 26N west of 135W, and from 10N to
15N between 115W and 135W with combined seas 8 to 10 ft in a
northwest swell. The 1030 mb high is forecast to remain nearly
stationary through early on Monday while weakening some, then
shift to the southeast to near 32N128W by early on Tuesday as
low pressure system and associated frontal system well west of
the discussion area tracks to the north-northeast. 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.
The northwest swell is forecast to gradually decay through
Tuesday allowing for the 8 to 10 ft seas to subside to 8 ft in a
small area from about 09N to 11N between 114W and 140W by early
in Tuesday.


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Page last modified: Sunday, 04-Dec-2016 16:06:05 UTC