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Eastern North Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 180305
TWDEP 

Tropical Weather Discussion  
NWS National Hurricane Center Miami FL
0405 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 0000 UTC surface analysis and satellite imagery through 
0300 UTC.      

.INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 

The monsoon trough extends W off the Pacific coast of Colombia 
at 08N78W across the Gulf of Panama to the Pacific coast of 
Costa Rica at 09N85W and then turns SW to 06N95W where 
scatterometer winds indicate a transition to an ITCZ, which then 
continues NW interrupted by a 1010 mb surface low at 09.5N119W, 
then wiggles W to beyond 09N140W. Isolated moderate to strong 
within 60 nm of line from 07N93W to 08N110W. Scattered moderate 
isolated strong convection is noted within 180 nm either side 
of a line from 10.5N111.5W to 07N136W.

...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 13N95W through 
late Tue. Model guidance suggests that stronger drainage flow on 
Tue night, and even hints at minimal gale force conditions 
developing briefly on Tue evening. 

Gulf of California: Light and variable winds expected through 
Sun evening. Moderate NW winds forecast across the entire gulf 
waters on Sun night into Mon morning, then the pressure gradient 
will relax with light NW flow through Mon night.

A weak NW to SE ridge extends across the Mexican offshore waters 
W of 100W, with gentle to moderate anticyclonic flow forecast 
around the meandering ridge through at least the middle of next 
week. 

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, are expected through 
the middle of next 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 1010 mb surface low is analyzed at 09.5N117W surrounded by 
a large area of long period northeasterly swell that is mixing 
with cross-equatorial swell across the waters S of 14N between 
93W and 120W. This swell will gradually subside to less than 8 
ft by the middle of next week as the surface low progresses 
westward. Model guidance suggests that a surface trough will 
develop near 09N117W early next week with an area of 8 ft seas 
continuing within 420 nm E of the trough axis as it shift W 
along the ITCZ.  

A cold front extends from 32N137W to 26N140W 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 night. The associated NW swell 
will subside to less than 8 ft on Mon night. 

Another round of NW swell, in the form of 7 to 11 ft seas, will 
reach 30N140W late Mon night. 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 17N106W 
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