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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 240321

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Thu Jun 24 2021

Tropical Weather Discussion for the eastern Pacific Ocean from
03.4S to 30N, east of 120W including the Gulf of California, and
from the Equator to 30N, between 120W and 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
0230 UTC.


Gale Warning: A 1008 mb low is analyzed near 12.5N97W associated
with a tropical wave that extends from 04N to coastal Mexico 
along 97W, moving west at 10 to 15 kt. Scattered moderate to 
strong convection is noted from 10N to 17N between 92W AND 102W..
Environmental conditions appear conducive for development of 
this system, and a tropical depression is expected to form during
the next couple of days as the disturbance moves west-
northwestward at about 10 mph. This system is expected to be near
the coast of southern or southwestern Mexico this weekend, and 
interests in those areas should monitor its progress for 
development. In addition to strong winds and large seas near this
system, the main weather impact will be the potential for heavy 
rainfall and flooding along the mountainous coastline from 
Guerrero to Jalisco. This is in the same general area that 
experienced heavy rainfall from Dolores a few days ago.


A second tropical wave extends from 05N to 16N along 110W, 
drifting west. Scattered moderate to strong convection is noted 
from 10N to 15N between 107W and 111W.


The monsoon trough extends from 10N74W to 08N82W to low pres 1008
mb near 12.5N97W to 10N120W. The ITCZ extends from 10N120W to 
13N130W to beyond 08N140W. In addition to the convection 
mentioned in the Special Features and Tropical Wave sections, 
scattered moderate isolated strong convection is from 04N to 09N
between 88W and 105W, and from 07.5N to 11N between 113W and 


A 0150 UTC ASCAT pass recently showed E to SE winds of 20-25 kt
within 90 nm E of the 1008 mb low near 12.5N97W, with these
strong E winds extending all the way to coast near Puerto Angel.
Seas area assumed to be around 8 ft and building within this area
of strong winds accompanying this low and tropical wave. These
deteriorating marine conditions will shift westward tonight
through Thu across the near and offshore waters of Oaxaca as the
low pressure gradually becomes better organized. Farther north
to 18N, gentle to moderate E to SE breezes prevail, with 4 to 6 
ft seas in a mix of SW and NW swell.

A gale warning is in effect for the offshore waters from western
Oaxaca to Michoacan effective Thu night and Fri. This is related
to the developing low pressure currently well south of the Gulf 
of Tehuantepec. There is a high chance this low will develop into
a tropical depression over the next couple of days. If this 
happens, gale conditions or higher are possible off Colima, 
Jalisco and south of Cabo San Lucas Fri night through Sun, then 
approaching Socorro Island Mon. 

Gentle to locally moderate NW winds prevail offshore of Baja
California tonight with seas of 4-5 ft. Similar southerly winds
prevail inside the Gulf of California. High pressure will begin
to build across the area from the NW Thu into the weekend to
freshen the wind flow across these waters.


Light to gentle easterly breezes prevail N of the monsoon trough
along 10N tonight, while light to gentle SW to W winds prevail S
of the trough. Slight to moderate seas of 5-7 ft in SW swell

For the forecast, conditions have begun to improve this evening
across the waters offshore of Guatemala and El Salvador and the
developing tropical wave shifts W of the area. Fresh NE gap 
winds will pulse through the Gulf of Papagayo tonight and Thu. 
Moderate to occasionally fresh SW swell will impact the waters 
off Ecuador, Colombia and into western Panama and Costa Rica 
through Sat. Elsewhere, light to gentle breezes will persist. New
SW swell will move into the regional waters Fri night through Sat
to raise seas to 6-8 ft over the weekend.


A high pressure ridge extends across the waters north of 20N and 
west of 125W and is centered on a 1025 mb high near 38N140W. The
pressure gradient between this area of high pressure and lower 
pressure within the monsoon trough/ITCZ is supporting gentle to 
moderate winds north of 08N and west of 125W. A broad trough is 
analyzed 128W to 130W, separating the monsoon trough and the 
ITCZ, where winds near 20 kt within 120 nm to the west of the 
trough and seas are 7-8 ft. Winds and seas will diminish through 
the latter part of the week in this area.