Tropical Weather Discussion
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AXPZ20 KNHC 231003

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
728 UTC Mon Jan 23 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 0600 UTC surface analysis and satellite imagery through
0900 UTC.


High pressure building in behind a vigorous cold front that
exiting the eastern Gulf of Mexico is tightening the pressure
gradient in the Gulf of Tehuantepec. This will cause winds to
increase to gale force by 1200 UTC. The high will slide quickly
eastward, and winds will quickly diminish below gale force later
this afternoon around 2100 UTC. Please see the latest East
Pacific high seas forecast under AWIPS/WMO headers HSFEP2/FZPN03
KNHC for further details.

Scatterometer data from 0330Z shows gales to the west of the
front north of 29N between 129W and 137W. Have upgraded the
forecast for this area accordingly. Altimeter data shows large
NW swell continuing to spreading across the waters with seas
greater than 12 ft north of 15N. Seas as high as 24 ft are
present near 30N. Large long period swell will continue to sweep
southeastward with 8 ft seas reaching the equator this afternoon.
Global models agree that the gale force winds over the northern
waters that are associated with the cold front will abate during
the next 12 hours as attendant low pressure to the west of the
Oregon coast weakens.


The ITCZ extends from 03N91W to 01N99W to 05N123W to 04N131W to
06N140W. No significant convection.


...A series of strong cold fronts has generated a large area
of unusually large swell. These swell will continue to affect
most of the forecast area through Wednesday...


Moderate to fresh west to southwest winds are observed as a cold
front enters Baja California Norte. Large long period NW swell
of 12 to 20 ft generated by gales behind the front will sweep
southeastward into the forecast zones. NW winds north of 27N will
become fresh to strong today, then subside. The pressure
gradient has tightened off the Jalisco Mexico coast as the front
approaches. This will briefly support fresh to strong winds today
within 120 nm of the coast. Ridging behind the front will allow
fresh to locally strong north winds to spread into the southern
Gulf of California to near Cabo Corrientes today. Strong winds
sustaining the swell event will diminish by Tuesday as the high
weakens, with seas decreasing below 12 ft in the offshore Mexico
waters Wednesday night. However, seas of 8 to 10 ft will persist
west of 100W through the end of the week.


Light to gentle winds will prevail across most of the region
through Tuesday. Seas will generally range between 3 and 5 ft
until Tuesday, then build about a foot in response to arriving
NW swell.

Gales behind the cold front entering Baja California are
affecting the northern waters. See the special features section
for additional details. Forecast models remain in general
agreement in developing an area of low pressure over the western
waters near 12N134W on Thursday and Thursday night, but are
trending smaller with respect to the size of the system.
Nevertheless, a large area of fresh to strong winds will be
possible in the vicinity of the low from 12N to 26N W of 120W by
Friday morning.

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