Tropical Weather Discussion
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AXPZ20 KNHC 100953

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
700 UTC Sat Dec 10 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 0600 UTC surface analysis and satellite imagery through
0900 UTC.


Gulf of Tehuantepec Gale Warning: The latest scatterometer passes
missed the western Gulf of Mexico and Gulf of Tehuantepec.
however, surface observations from Coatzalcoalcos Mexico have been
consistently showing NW winds of around 30 kt during the past
several hours. A strong ridge of high pressure over eastern Mexico
is maintaining a tight pressure gradient over the Isthmus of
Tehuantepec. This gradient is expected to support sustained winds
to around 40 kt over the Gulf of Tehuantepec today and tonight,
then the gradient will slacken as high pressure over the western
Gulf of Mexico weakens and shifts eastward. Seas will be peaking
around 18 ft early this morning, then will subside below 8 ft
Sunday night. Gale conditions will persist until Sunday morning,
then pulse between 20 and 30 kt each night from Sunday night
through Tuesday night.


The monsoon trough axis extends from 08N77W to 08N87W to 06N92W
to 06N98W. The ITCZ continues from 06N98W to 06N102W to 09N117W
to 07N129W to beyond 08N140W. Scattered moderate and isolated
strong convection is present from 08N to 12N between 109W and



Gulf of California: A weakening pressure gradient between a
surface trough along the Mexico coast and high pressure over the
east Pacific will maintain fresh northwest winds over the Gulf of
California S of 27N tonight. High pressure northwest of the area
will weaken by this evening, allowing gentle to moderate winds to
ensue through mid-week.

Ridging dominates elsewhere over the offshore waters of Mexico
resulting from 1026 mb high pressure centered near 29N127W. Aside
from the Tehuantepec high wind event, light to gentle winds will
prevail S of 17N through the forecast period. Fresh to
occasionally strong northwest winds west of Baja California will
continue through Sunday night, then become moderate to fresh as
the ridge weakens in response to low pressure approaching from
the NW. Between 17N and Mazatlan moderate to fresh northwest winds
will prevail through Tuesday night.


Gulf of Papagayo: Fresh to strong offshore winds east of 94W will
continue to pulse mainly during the overnight hours this weekend.
Max seas during this event will be around 9 ft. An easterly wave
over the central Caribbean will cross Central America Monday. Some
model guidance calls for low pressure development along the wave
axis as it moves westward away from Costa Rica on Tuesday and
Wednesday. Model guidance consensus and climatology both suggest
this system will remain a trough or weak low during this time

Light to gentle north to northeast winds and combined seas of 3
to 5 ft are occurring north of the monsoon trough, which is
expected to meander between 08N and 10N through Wednesday. Light
to moderate southwest winds are observed from 05N to 09N, with
combined seas hovering between 3 and 5 ft in southwest swell.
Moderate to fresh southerly flow is expected south of 05N through


High pressure centered near 29N127W ridges southeast to near
19N109W. Gentle to moderate north-northwest flow is expected
northeast of the ridge axis this weekend and moderate to fresh
trades will prevail south of the ridge axis, north of the ITCZ.
Fresh to occasionally strong NE winds and combined seas of 8 to 9
ft will generally prevail from 07N to 17N W of 122W through Monday
morning. Low pressure encroaching on the far northwest waters will
weaken the ridge and maintain a relatively light wind regime in
this area Tuesday through Friday.

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