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Eastern North Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 182148
TWDEP 

Tropical Weather Discussion  
NWS National Hurricane Center Miami FL
2205 UTC Sun Nov 18 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 
2145 UTC.      

.INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 

The monsoon trough extends SW off the Pacific coast of Colombia 
at 08N78W across the southern Gulf of Panama then turns NW to 
the Pacific coast of Costa Rica at 09N84W, then turns SW again 
to 07N101W where scatterometer winds indicate a transition to an 
ITCZ, which then continues NW interrupted by a 1011 mb surface 
low at 10N122W. The monsoon trough then wiggles W to another 
1011 mb low pres at 09N133W.

Scattered moderate isolated strong convection is noted N of 03N 
E of 85W, within 90 nm either side of a line from 09N96W to 
07N101W, and within 150 nm either side of a line from 06N108W to 
09N122W. Isolated moderate to strong convection is noted from 
05N to 13N between 128W and 140W.     

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO... 

Gulf of Tehuantepec...Strong to near gale force northerly winds 
will pulse across the gulf waters and as far S as 13.5N96W 
through late Tue. Model guidance suggests that stronger drainage 
flow on Tue night resulting in minimal gale force conditions 
developing and continuing through mid morning on Wed.

Gulf of California: Light and variable winds currently observed 
will become a moderate NW breeze briefly on Mon morning, then 
the pressure gradient will relax with light NW flow through Wed 
except light an variable over the northern waters as a weak 
front passes.  

A 1018 mb surface high is meandering near 26N120W with a ridge 
extending across the Mexican offshore waters W of 97W, with 
gentle to locally moderate anticyclonic flow forecast around the 
meandering ridge through at least the middle of next week with a 
weak cold front shifting E across the waters N of 28N on Wed 
accompanied by a light and variable wind shift. 

Long-period NW swell, in the form of 7 to 9 ft seas, will arrive 
at 30N120W late Thu and reach the northern coast of the Baja 
Peninsula early Fri. 

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

Gulf of Papagayo...Fresh to locally strong NE winds, with seas 
building briefly to 8 ft well downstream near 10.5N87W, are 
expected this week, with these strong winds reaching as far SW 
as 10.5N88.5W.

Light to locally moderate northerly flow is forecast elsewhere N 
of the monsoon trough, while moderate southwesterly monsoonal 
flow, with 4 to 6 ft seas, is forecast S of the monsoon trough 
through the middle of next week.

REMAINDER OF THE AREA...  

A 1011 mb surface low is analyzed at 10N122W and another is 
analyzed at 09N133W. These low will continue W accompanied by
fresh E wind and seas to 8 ft through early Wed.  

A cold front extends from 32N129W to 22N139W accompanied by a 
fresh SW-W-NW wind shift, and 7 to 10 ft seas W of the front in 
long-period NW swell. Although the front will weaken it will 
reach the Baja Peninsula on Wed evening. The associated NW swell 
will subside to less than 8 ft on Mon night. A second cold front 
will move into the area on Mon followed briefly by NW swell, in 
the form of 6 to 8 ft seas. A tightening pressure gradient will 
result in strong W winds N of 30N between 125W and 140W on Tue 
night into Wed. A ridge will set up from 29N140W to 18N106W on 
Wed night with strong NE trades, and seas to 11 ft, forecast 
from 11N to 22N W of 127W on Thu, surrounded by NW swell 
resulting in 7-9 ft seas across the waters elsewhere N of the 
ITCZ W of 120W.

$$
Nelson