947 
AXPZ20 KNHC 180402
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Tue Sep 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. 

...SPECIAL FEATURE... 

The low pressure currently centered southwest of the 
Revillagigedo Islands is expected to stay nearly stationary 
through Tue evening, then will start tracking NNE and reach 
central Baja early on Thu. Fresh to locally strong winds and 
building seas to 9 ft are forecast for the southern and central 
Gulf of California starting Wed evening. Winds and seas in this 
portion of the gulf will continue through Thu evening when the 
low/possible tropical cyclone will be inland Baja California or 
likely already dissipated. As indicated in the latest Tropical 
Weather Outlook, although environmental conditions appear 
conducive for tropical cyclone formation, the large size of the 
system and possible land interaction should prevent any 
significant or rapid development from occurring during the next 
two days. However, there is still a medium chance of this system 
becoming a tropical depression Wednesday or Thursday. Regardless 
of development, this broad disturbance will likely produce very 
heavy rainfall over Baja California Sur later this week. 

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

The monsoon trough axis extends from northern Colombia near 
09N75W and continues to 10N90W to 09N105W, then resumes from 
20N105W to a 1007 MB low near 18N113W to a 1006 mb low near 
15N120W to 12N126W. The ITCZ begins near 12N126W and continues 
beyond 12N140W. Scattered moderate convection is from 07N to 11N 
between 82W and 89W, from 07N to 13N between 103W and 108W, from 
12N to 20N east of 118W, from 10N to 19N between 120W 
and 126W, and from 07N to 16N west of 133W. 

...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 and southern Gulf of California as a low pressure or 
possible tropical cyclone traverses the area Thu. See the 
Special Features section above for further details.

Building pressure to the NW is generating fresh winds W of Baja 
California Norte tonight through Wed morning. On the other hand, 
N swell will cause seas to build to just above 8 ft generally N 
of 27N between 118W and 127W Tue night through Thu night. 
Otherwise, 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. 

Variable light to gentle winds will be elsewhere, except for 
moderate NE gap winds in the Gulf of Tehuantepec through Thu. 
Seas are forecast to be in the 4 to 7 ft range.

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...   

A slightly tight pressure gradient between a 1025 mb high 
centered northwest of the area and the ITCZ supports fresh winds 
from 16N to 23N west of 134W with seas less than 8 ft. The 
center of high pressure is forecast to gradually strengthen 
while it moves east-southeast N of the area. This will allow for 
the re-development of fresh to strong winds in this region with 
seas to 9 ft. Enhanced winds and seas in this area is forecast 
to prevail through Thu in the afternoon.

Finally, the center of low pressure located SW of the 
Revillagigedo Islands will continue to track WSW along with 
fresh to strong winds within 300 nm northwest quadrant of it. 
Seas in this region of the low will be in the 8 to 9 ft range. 
The low is forecast to weaken slowly Fri and Sat, and the 
associated winds and seas will subside.

$$
Ramos