Tropical Weather Discussion
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000
AXPZ20 KNHC 212124
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 UTC Sat Apr 21 2018

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 1800 UTC surface analysis and satellite imagery through
2045 UTC.

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

A surface trough extends from 09N74W TO 06N84W TO 07N91W TO
05N102W. The ITCZ continues from 05N102W TO 07N112W TO 08N134W
to beyond 07N140W. Scattered to locally numerous moderate to
strong convection is present from 4.5N TO 08N BETWEEN 81W AND
89W. Scattered moderate to strong convection is present from 05N
TO 08N BETWEEN 89W AND 104W. Scattered moderate to strong
convection is present from 06N TO 10N between 111W AND 115W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Fresh NW winds and seas of 5 to 7 ft prevail across the offshore
waters of Baja California as a modest pressure gradient
continues between a ridge building in from the NW and lower
pressure over the SW United States and NW Mexico. Winds and seas
W of the peninsula will diminish Sun through Tue as the high to
the NW weakens and lower pressure over the SW United States and
NW Mexico fills and shifts east. Gentle NW winds prevail over
the N Gulf of California, while moderate NW winds are observed
through the central Gulf. Winds will subside as well over the
Gulf Sun through Tue as the high gradually weakens the area of
low pressure weakens and moves east.

N winds across the Gulf of Tehuantepec have diminished to around
15 kt this afternoon and will become light and variable through
this evening, while seas subside to 6 ft or less. Another cold
front entering the NW Gulf of Mexico could induce the next gap
wind event over the Gulf of Tehuantepec Mon through Thu. Gales
are not expected during this event.

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

Gulf of Papagayo: Fresh NE to E winds across the region are
expected to pulse between nightfall and mid morning to 20-25 kt
across and downstream of the Gulf of Papagayo through at least
Tue night with seas peaking each episode between 7 and 9 ft.

Gulf of Panama: Gentle N to NE winds and seas of 5 to 7 ft in SW
swell prevail across the Gulf of Panama and offshore of Panama
and Colombia to 250 nm today. Very active convection continues
across the region this afternoon, and has shifted slightly W and
is concentrated mainly between 80W and 89W. Winds across the
Gulf will become gentle to moderate tonight through Mon, while
farther offshore and SW, gentle to moderate SW winds will
prevail Sun through Wed. Corresponding seas will generally run
between 4 and 6 ft.

Elsewhere, mainly light to gentle winds are expected S of 06N
through Wed. Cross-equatorial swell will mix with residual swell
downwind from Papagayo through Wed, and maintain seas in this
area between 5 and 7 ft. Elsewhere seas will subside to 3-5 ft by
Sun as long period SW swell from the Southern Hemisphere decay,
then rebuild to between 5 and 7 ft on Mon and Tue as another
round of SW swell arrive.

REMAINDER OF THE AREA...

Strong high pressure is centered will offshore of Northern
California near 41N134W. The high ridges SE across the northern
forecast waters to near the Revillagigedo Islands. The pressure
gradient between the ITCZ and the high to the north will support
fresh to strong NE trades N of the ITCZ generally between 07N
and 20N W of 120W through tonight. The combination of these
winds, NW swell and SW swell will support combined seas of 8 to
10 ft over these waters into Saturday, expanding N to near 30N
by Sunday as NW swell propagates into the northern waters. The
NW swell will begin to decay below 8 ft Sunday night before
becoming reinforced by another pulse of NW swell by Monday
night.

Cross equatorial SW swell moving into the southern forecast
waters continues to decay and seas have subsided to 8 ft or less
near the equator. Another round of SW swell could cause waters
near the equator to build to near 8 ft Sun through Tue.

$$
Stripling



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