Tropical Weather Discussion
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AXPZ20 KNHC 300228

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Tue May 30 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.


The Monsoon Trough axis extends from a low in NW Colombia near
09N74W to 08N84W to a 1009 mb low pressure near 13N100W to
09N114W. The ITCZ axis then continues from 09N114W to 06N126W
to beyond 07N140W. Scattered moderate convection is noted within
60 nm south of the axis between 84W and 85W.



Moderate to fresh northwest winds continue to prevail west of
the Gulf of California through Thursday night as a result of the
pressure gradient between high pressure to the west and surface
troughs over Baja California and mainland Mexico. The high will
weaken some after Thursday night and Friday allowing for these
winds to diminish to mainly moderate category. On Tuesday,
models continue to forecast low pressure to deepen over the
interior portion of the western United States. The combination
of this and high pressure present to the west of the Baja
California will tighten the pressure gradient just west and
northwest of Baja California Norte, resulting in fresh northwest
winds and combined seas of 7 to 9 ft in northwest swell north of
29N between 120W and 126W beginning on Tuesday afternoon, and
spreading southward to neat 27N between 119W and 124W by
Wednesday afternoon.

Mainly light to gentle southeast to south winds are expected
over the Gulf of California through early Tuesday, then increase
to gentle to moderate winds Tuesday night and Wednesday. Seas
will be in the range of 1 to 2 ft, except for slightly higher
seas of 3 to 4 ft over the entrance to the Gulf of California.

Elsewhere, a 1009 mb low centered near 13N100W is associated
with a broad area of low pressure that is located to the south
of southern Mexico. This area of low pressure will slowly
lift northward through Wednesday. Given that the atmosphere
surrounding this low pressure is very moist as observed in
TPW animated imagery and very unstable at the time, expect
clusters of scattered showers and thunderstorms to persist along
and just offshore the coast of southeastern Mexico, including
the Gulf of Tehuantepec through the next few days. Presently,
scattered to numerous showers and thunderstorms are observed
from 12N to 15N between 92W and 96W. Scattered showers and
thunderstorms are occurring from 09N to 11N between 98W and
102W, and also within 30 nm of a line from 08.5N102W to 09N106W.
Heavy rainfall and localized flooding will be possible over the
coastal sections of Mexico through this week. Gusty winds and
seas briefly reaching to 8 ft will be possible with the strongest
of the shower and thunderstorm activity. Gradual development of
the low pressure is possible as well during the week. Otherwise,
mainly light to gentle winds and seas of 5 to 7 ft will prevail
over the Mexican offshore waters south of the Baja California
Peninsula through Wednesday.


Moisture southerly flow associated with the Monsoon Trough axis
that stretches from NW Colombia to near 10N90W will continue
to provide support for scattered to numerous showers and
thunderstorms mainly north of 04N. Some of this activity may
contain strong gusty winds and rough seas. Light to gentle winds
will prevail north of the trough axis with 4 to 6 ft seas.
Mainly moderate south to southwest winds are expected south of
the trough axis with seas of 5 to 7 ft.


High pressure of 1024 mb is centered near 30N133W with a ridge
extending southeastward to 26N126W and to near 20N118W. High
pressure covers the area north of 16N and west of 117W. The
associated gradient between the ridge and lower pressure to the
south in the deep tropics is supporting fresh northeast trades
from 07N to 15N west of 133W, with seas of 7 to 9 ft in mixed
northeast and southeast swell. This area of winds and seas is
forecast to gradually shrink through Wednesday as the ridge
retreats westward. Seas of 6 to 8 ft in mixed northeast and
southeast swell will linger within the same general area by
Wednesday. Gentle to moderate trade winds will continue over
the remainder of the northwestern waters through Wednesday with
5 to 7 ft seas. Fresh northwest winds are forecast to develop
north of 27N and east of 125W tonight as the pressure gradient
between low pressure deepening inland over the SW United States
and high pressure over the northwest and north/central waters
tightens. These winds will support 7 to 9 ft seas over that area
through Wednesday night.

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