945 
AXPZ20 KNHC 160954
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Sun Sep 16 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 0600 UTC surface analysis and satellite imagery through 
0900 UTC. 

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 

The monsoon trough axis extends from 1009 mb low pressure 
centered over northern Colombia near 10N75W to 11N90W to 16N101W 
to low pressure 1007 mb centered near 18N115W to 11N123W to 
beyond 11N140W. Scattered moderate isolated strong convection is 
from 06N to 13N east of 96W and from 10N to 21N between 100W and 
118W. Scattered moderate convection is from 07N to 13N west of 
124W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO... 

A surface trough over the Baja Peninsula will generally maintain
light to moderate winds over the Gulf of California through Tue 
night. During the second half of the week winds are forecast to 
increase to moderate to fresh speeds over the Gulf in response to
a high pressure ridge building to the NW. This same ridge of 
high pressure will generate fresh to strong winds W of 
California, which will generate NW swell. These swell will cause 
seas to build to above 8 ft N of 26N between 121W and 131W 
during the day on Thu.

Gentle to moderate NW flow will prevail across the offshore 
waters W of Baja California, with seas generally in the 5 to 7 
ft range. Expect moderate to fresh NW winds, and seas of 6 to 8 
ft N of Punta Eugenia today as the pressure gradient tightens 
with a ridge building in from the NW. Additional pulses of long 
period S swell will continue to impact the entrance of the Gulf 
of California, and the waters W of Baja California through Wed.

Moderate to fresh monsoonal flow along with a 1007 mb low 
located west of the Revillagigedo Islands near 18N115W are 
supporting seas to 8 ft in the offshore waters from Jalisco to 
Oaxaca. This low is forecast to drift west of the Baja 
California Sur offshore waters today, thus allowing for a 
decrease in the winds and seas. Another low pres is forecast to 
develop just west of the Revillagigedo Islands early on Mon. The 
low is expected to be nearly stationary through Tue evening when 
it is forecast to start tracking N-NW toward central Baja by 
Fri. This system has a high chance of becoming a tropical 
cyclone by the middle of next week. 

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

The monsoon trough is expected to remain in the vicinity of 10N 
to 12N during the next several days. Winds will be gentle to 
moderate N of the trough and moderate to fresh S of the trough 
as a large area of disturbed weather prevails.

Cross-equatorial SW swell are decaying but will continue to 
impact the coast of Central America through Wed. Seas of 8 to 9 
ft are affecting the waters between Ecuador and the Galapagos 
Islands, and also reach to near the Azuero Peninsula. These 
marine conditions are forecast to subside tonight and Mon. The 
next round of SW swell is not expected until at least the end of 
next week.

REMAINDER OF THE AREA...   

A weakening surface trough constituting the remnants of Paul, 
extends from 17N134W to 25N137W. The trough will continue to 
move west and is forecast to pass 140W tonight. High pressure 
will build north of the trough today, which will slightly 
tighten the pressure gradient. This will result on fresh to 
locally strong winds from 21N to 24N west of 135W with seas 
ranging from 8 to 10 ft. 

Otherwise, the low west of the Revillagigedo Islands will 
continue to track west-southwest through the end of next week. 
With a slightly increase in the pressure gradient, this low will 
support fresh to strong winds mainly in its northern semicircle 
starting on Tue and continuing through Thu. 

$$
Ramos