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Eastern North Pacific Tropical Weather Discussion (Text)



000
AXPZ20 KNHC 201538
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1339 UTC Fri Oct 20 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 1200 UTC surface analysis and satellite imagery through
1430 UTC.

...TROPICAL WAVES...

The axis of a tropical wave runs from 08N93W to 16N94W, moving W
around 5 kt. Scattered moderate and isolated strong convection 
is seen from 09N to 12N between 90W and 97W. 

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

The monsoon trough extends from 11N85W to 08N100W to 08N121W. 
The ITCZ continues from 08N121W to 09N126W to 08N132W to beyond 
09N140W. Scattered moderate and isolated strong convection is 
noted from 07N to 09N between 97W and 104W, from 10N to 12N 
between 123W and 129W and from 13N to 15N between 136W and 139W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

High pressure over the western Gulf of Mexico and eastern slopes
of the Sierra Madre Oriental has weakened during the past 24 
hours. This has loosened the pressure gradient over the Gulf of 
Tehuantepec and allowed the latest gale force gap wind event to 
end. Winds have decreased to between 20 and 25 kt. The pressure 
gradient will weaken further this weekend with winds diminishing 
to 20 kt or less Saturday. Another cold front will enter the Gulf
of Mexico on Sunday evening. This front will bring strong to 
near gale force winds to the Gulf of Tehuantepec Sun night and 
gale force winds to the Gulf of Tehuantepec Mon night through Wed
night.

The pressure gradient between building high pressure northwest 
of the Baja California Peninsula and a surface trough over the 
Gulf of California will strengthen winds west of Baja California 
Norte early this weekend. Strong NW winds will extends down the 
peninsula as far S as 24N on Sat morning. Winds are expected to 
diminish to 20 kt or less by Late Saturday. Long period NW swell 
generated to the NW of a weakening cold front over the NW corner 
of the discussion area will begin invading the waters off Baja 
California Norte this afternoon. Seas will peak near 15 ft off 
the northernmost coast of Baja California Norte Saturday before 
starting to subside. The swell will propagate SE, with seas 8 ft 
or greater enveloping all of the offshore forecast zones W of 
Baja California through the weekend before subsiding below 8 ft N
of 26N by Tue afternoon. 

High pressure building over the Great Basin region of the 
western United States will cause NW winds to strengthen over the 
Gulf of California from Saturday night through Tuesday. Winds 
will be strongest on Mon when seas peak around 8 ft.

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

Gentle to moderate winds will prevail over the forecast area the
next several days. Seas of 8 to 9 ft maintained by decaying SE 
and S swell across the southernmost zones W of Ecuador will 
subside by early Saturday. Moderate to fresh SW winds will cause 
seas to build to around 8 ft W of Colombia and S of Panama 
between 03N and 06N between 80W and 84W on Saturday.

REMAINDER OF THE AREA...

A weakening cold front over the far northwest waters has already
introduced a fresh set of large NW swells to the area. Seas near
15 ft will spread west to east from 133W over the waters north 
of 28N today. The swell will push southeastward across most of 
the region, while gradually subsiding, the next few days. Highest
seas will drop below 12 ft Sunday afternoon and seas associated 
to this swell are expected to subside below 8 ft by Wednesday. A 
surface trough has generated a small area of 20 to 25 kt winds 
over a portion of the far westernmost waters from 22N to 25N W of
137W. This area of winds will shift W of 140W by this evening as
the surface trough migrates west.

$$
CAM

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Page last modified: Friday, 20-Oct-2017 15:38:52 UTC