Tropical Weather Discussion
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AXPZ20 KNHC 220219

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0215 UTC Sat Oct 21 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 0000 UTC surface analysis and satellite imagery through
0215 UTC.


Gulf of Tehuantepec Gale Warning: Fresh to strong northerly flow
will develop by Sunday evening as the pressure gradient N of the
area tightens combined with nighttime drainage flow. The
pressure gradient will continue to tighten thereafter and winds
will increase to gale force by early Monday morning as a cold
front moves through the western Gulf of Mexico. Cool and dry air
behind the front will reinforce already present local drainage
effects allowing the gale to persist through much of the week.
Winds may even approach minimal storm force by early Wednesday.
Seas will build to up to 18 ft by mid-week.


A tropical wave is N of 07N along 99W moving W at around 10 kt.
Scattered moderate and isolated strong convection is from 07N to
10N between 98W and 102W.


The monsoon trough axis extends from 07N74W to 10N90W to 08N100W
to 10N110W to 09N120W. The intertropical convergence zone axis
extends from 09N120W TO 09N130W TO 09N140W. Scattered moderate
and isolated strong convection is within 180 nm S of axis E of
84W, within 150 nm NW of axis between 111W and 118W, and from
07N to 11N W of 128W.



Please see the special features section above for information on
a developing gale event in the Gulf of Tehuantepec.

Fresh to locally strong NW winds are ongoing off the coast of
Baja California N of Cabo San Lazaro between strong high
pressure W of the area and troughing over the SW United States
and N central Mexico. These winds will diminish this evening as
the troughing weakens. Seas will are peaking near 16 ft off the
northernmost coast of Baja California Norte in northerly swell,
and are expected to subside through early next week as winds
diminish and the swell decays. The swell will propagate SE, with
seas 8 ft or greater covering all of the offshore forecast zones
W of Baja California through the remainder of the weekend before
subsiding to less than 8 ft by the middle of next week.

High pressure building over the Great Basin region of the
western United States will cause NW winds to strengthen over the
Gulf of California through Tuesday, diminishing thereafter as the
gradient weakens. Winds will be the strongest on Sunday night
through Monday when seas peak around 8 ft.


Gentle to moderate winds will prevail over the forecast area the
next several days, except increasing to moderate to fresh S of
the monsoon trough by Monday afternoon. NW swell originating
from the Gulf of Tehuantepec will propagate into the offshore
waters of Guatemala and El Salvador by the middle of next week.


A set of large NW swell with seas near 16 ft will continue to
propagate SE while gradually subsiding into early next week. Seas
will subside to less than 12 ft Sunday afternoon. Seas
associated to this swell are expected to further subside, to
less than 8 ft, by mid week.

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