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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 190959

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Sun May 19 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 0600 UTC surface analysis and satellite imagery through
0945 UTC.


The monsoon trough axis extends from northwest Colombia near 
10N75W to across northern Panama, then to the coast at 09N84W.
It continues from there to a 1008 mb low pressure near 11N93W
to 11N105W and to 07N119W, where an overnight scatterometer pass 
indicated that it transitions to the ITCZ and continues to
06N129W and to beyond the area at 05N140W. Scattered strong
convection is seen within 150 nm north of the ITCZ between 122W
and 126W. Scattered strong convection is within 150 nm north of 
the ITCZ between 122W and 126W. Scattered moderate to strong
convection is within 60 nm south of the ITCZ between 122W and
126W, and within 30 nm of the trough and ITCZ between 118W and
121W. Scattered moderate to isolated strong convection is within
60 nm north of the trough between 113W and 118W. Scattered 
moderate convection is noted within 60 nm south of the trough 
between 78W and 81W, and within 60 nm north of the trough 
between 108W and 113W.



The overnight Ascat pass showed moderate to fresh northwest winds 
offshore the Baja California coast mainly north of Cabo San
Lazaro. Waveheights over these waters are in the range of 6-8 ft
due primarily to southerly swell, but also with a component of 
northwest swell. Gentle to moderate northwest winds are over the
offshore waters south of Cabo San Lazaro. Waveheights there are 
in the 5-7 ft range from southwest swell.

Relatively weak high pressure over these waters will weaken
slightly today in response to the next cold front to impact the 
forecast waters. This front will move across the waters off Baja 
California Norte and over the northern Gulf of California this 
evening through early Mon while it quickly weakens, eventually 
dissipating by early Mon afternoon. Before the front dissipates, 
a tight gradient will develop out ahead it inducing strong west 
to northwest winds over the far northern Gulf of California this
evening and tonight. The gradient will slacken Mon afternoon
allowing for these winds to diminish.

Wave model guidance suggests that a large set of long-period 
southerly swell will continue to propagate through the forecast 
waters through the period, except mixing with northwest swell 
left behind in the wake of the aforementioned cold front over 
the waters west of Baja California through Tue night.

Looking ahead, another cold front may move across Baja 
California Norte and the northern Gulf of California by the 
middle part of the upcoming week followed by much stronger high 
pressure. Per latest model guidance this new high pressure is 
expected to usher strong northerly winds and building waveheights
across much of the northern waters at that time.


A weak pressure pattern will maintain gentle to moderate onshore
winds across most of the region for the next several days. Large
cross-equatorial southwest swell off Ecuador will move into the 
outer offshore waters of Central America beginning tonight and 
into the middle part of the upcoming week. 

Plenty of atmospheric moisture over this region will help 
contribute to the development of scattered, to at times, 
numerous showers and thunderstorms over these waters well into 
the upcoming week. Some of this activity may be capable of 
producing very heavy rain and strong gusty winds.


A cold front extending from near 32N124W to 27N131W and to 
26N138W will begin to weaken as it reaches a position from near 
Baja California Norte to 27N122W and to 24N136W this evening,
and dissipate by early Mon afternoon as it pushes southeastward 
across central Baja California. A set of northwest swell is 
following in behind the front, with waveheights in the range of 
8-11 ft. The swell will propagate as far south as 19N and west
of 111W by late Mon. The waveheights will peak to 11 or 12 ft
over the far northeast forecast waters before the swell begins 
to slowly decay late on Mon. As high pressure builds in behind
the front, the present moderate to fresh trade winds occurring 
from 07N to 20N west of 120W will become mainly fresh in speeds
while increasing in coverage well into the upcoming week. The 
combination of the northerly swell, a component of southerly 
swell and local winds will allow for waveheights within this 
area of trade winds to build west of 120W through mid week. 
Increased trade wind convergence will also allow for showers and
thunderstorms to increase along the ITCZ from Mon through late