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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 212159

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 UTC Sun Jul 21 2019

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. 


Gale Warning: Satellite imagery continue to show a low pressure 
system located near 12.9N116.5W gradually becoming better 
defined. Thunderstorm activity has been steadily increasing and 
becoming better organized, and a tropical depression or a 
tropical storm is expected to form during the next day or so. 
Scattered moderate convection is noted within 120 nm NW 
semicircle of the low. The disturbance is forecast to move 
generally northwestward at around 10 mph, remaining well 
offshore the coast of Mexico. Winds are expected to increase to 
minimal gale force by Mon morning, and there is a high chance of 
tropical storm development. The system will pass west of Clarion 
Island Mon night and Tue, with 8-10 ft seas expected near the 

Please see the latest eastern North Pacific Tropical Weather 
Outlook at for more information.


A tropical wave with axis near 81W extends southward from the 
western Caribbean Sea into the far eastern Pacific. Numerous 
moderate scattered strong convection is noted from 04N to 09N 
east of 92W.

A tropical wave with axis near 95W is moving west around 10-15 
kt. Scattered moderate isolated strong convection is noted from
05N to 12N between 93W and 100W.

A tropical wave with axis along 122W is moving west around 10-15 
kt. There is no significant convection associated with the wave 
at this time. 


The monsoon trough extends from 06N77W to 06N82W to 08N86W to 
07N100W to 15N112W to 07N124W. The ITCZ extends from 07N124W to 
04N132W to 04N140W. Numerous moderate scattered strong 
convection is from 04N to 09N E of 92W. Scattered moderate 
convection is from 10N to 21N between 102W and 112W, and 
from 03N to 07N between 126W and 136W.


The primary forecast concern through mid week will be the track 
of the developing low pressure system near 12.9N116.5W. The low 
pressure is forecast to pass west of Clarion Island by Tue 
morning as a gale center or tropical storm. Seas of 8-10 ft are 
expected to impact the waters near Clarion Island late Mon into 
Tue as the low moves past. Please see the Special Features 
section above for more information on this system.

Upper level diffluence just south of Baja California continue to 
support scattered showers and thunderstorms over the offshore 
waters between Cabo Corrientes and Petatlan, Mexico including a 
portion of the entrance to the Gulf of California. Weak ridging 
over the northern waters is supporting light to locally moderate 
NW winds off Baja California. The same ridge also supports 
gentle to moderate SE flow over the Gulf of California, except N 
of 29N where fresh to locally strong winds are noted. Little 
change is expected over the next couple days. Weak high pressure 
building in the wake of the aforementioned low will enhance 
winds to fresh speeds along the coast south of Cabo Corrientes 
Mon night into Tue. 

Otherwise, brief pulses to 20 kt are possible in the Gulf of 
Tehuantepec through the middle of this week.


The pressure gradient across Central America is maintaining 
fresh to strong NE to E winds near and downstream of the Gulf of 
Papagayo. Fresh to locally strong winds will continue pulsing 
across the Gulf through early Tue with the strongest winds 
occurring during the overnight and early morning hours. Seas 
will peak around 8 ft each morning downstream of the Gulf. Fresh 
to strong winds will resume Thu night and continue through Sat. 
Elsewhere, moderate winds south of the monsoon trough will 
strengthen to fresh speeds tonight and Mon, with seas building 
to 8-9 ft off the coast of Panama and Colombia. Looking ahead, 
seas will build to 8 ft or greater over the southern waters Wed 
through Thu in long period S to SW swell.


A broad area of fresh to strong winds prevail in the vicinity of 
an elongated low pressure along the monsoon trough over the 
waters between 111W-118W. Please see the Special Features 
section above for more information on the high potential for 
tropical cyclone development in this region.

Elsewhere, weak low pressure centered near 17N134W will open up 
into a trough this evening and likely dissipate overnight. 
Moderate to fresh trade winds are occurring roughly north of 20N 
and west of 130W between weak ridging north of the area and the 
low pressure mentioned above. Latest altimeter data show seas 
are less than 8 ft seas in the vicinity of the low.