710 
AXPZ20 KNHC 171541
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1420 UTC Mon Sep 17 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 1200 UTC surface analysis and satellite imagery through
1415 UTC. 

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

The monsoon trough axis extends from northern Colombia near 
09N73W to 09N93W to 18N111W to low pressure 1007 mb centered near
16N118W to beyond 09N140W. Numerous moderate and scattered 
strong convection is seen within 90 nm of 15N121W. Scattered 
moderate and isolated strong convection is found elsewhere within
240 nm either side of a line from 20N106W to 14N122W. Scattered 
moderate isolated strong convection is observed within 90 nm 
either side of a line from 08N83W to 08N101W to 11N104W and 
within 150 nm of the monsoon trough axis W of 135W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO... 

A surface trough over the Baja Peninsula will maintain light to 
moderate winds over the Gulf of California through Tue morning. 
Afterwards, the winds are forecast to increase to moderate to 
fresh speeds in response to a high pressure ridge building to the
NW. Winds over the gulf N of 29N are forecast to become strong 
and from the S to SE early on Wed continuing through Thu 
morning. Fresh to strong winds are then expected to develop 
over the central Gulf of California as low pres traverses the
area Thu.

Building pressure to the NW will also generate fresh winds W of 
Baja California Norte tonight through Wed morning with 
corresponding seas to 8 ft. Pulses of long period SW swell will 
continue to impact the entrance of the Gulf of California, and 
the waters W of Baja California through Tue night. 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 generally N of 27N between 119W and 
129W Tue night through Thu night.

Moderate to fresh monsoonal flow will team up with a 1007 mb low
centered SW of the Revillagigedo Islands near 17N119W to support
seas to 9 ft in the offshore waters between Jalisco and the 
Revillagigedo Islands south of 21N. This low is forecast to 
continue a southwest track the next three days, thus allowing for
a decrease in the winds and seas in the offshores of Baja 
California Sur today. A new center of low pres is forecast to 
develop just west of the Revillagigedo Islands tonight. The low 
is expected to stay nearly stationary through Tue evening, then 
it will start tracking NNE and reach central Baja early on Thu. 
There is still a high chance of this system on becoming a 
tropical cyclone within the next 5 days.

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 07N 
to 12N during the next several days. Winds will be light to 
gentle N of the trough and gentle to moderate S of the trough.

Cross-equatorial SW swell will continue to impact the coast of 
Central America through Tue night followed by a modest pulse of 
long period swell with up to a 20 second period reaching the 
coastal waters on Wed morning. Seas are expected to be in the 5 
to 7 ft range.

REMAINDER OF THE AREA...   

The surface trough, remnant of Paul, has passed to the west of 
the area. However, a tightening pressure gradient between this 
feature and a 1021 mb high centered just north of the area near 
31.5N138W supports fresh to strong east winds from 16N to 26N 
west of 134W. Latest satellite-derived wind data indicates strong
winds in this region. Enhanced winds and seas in this area will 
persist through Thu.

Otherwise, the low currently centered SW of the Revillagigedo 
Islands near 16N118W will continue to track WSW during the next 
few days. The area of winds and seas associated with this low 
will gradually expand and combine with the area of winds and seas
mentioned in the previous paragraph by late Tue night.

$$
CAM