000
AXPZ20 KNHC 172050
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 UTC Sat Sep 17 2016

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
2100 UTC.

...SPECIAL FEATURES...

1006 mb low pressure centered near 15N107W has high probability
of developing into a tropical cyclone during the next 48 hours.
Convective activity has increased in the northwest quadrant of
the circulation with numerous moderate and isolated strong
convection noted from 15N to 19N between 106W and 110W. A gale
warning is in effect for this system, in anticipation of strong 
winds associated with an intensifying low. See the latest high
seas forecast under AWIPS/WMO headers MIAHSFEP2/FZPN03 KNHC for
more details on the gale warning. See latest tropical weather
outlook for the eastern north Pacific TWOEP/ABPZ20 KNHC for more
on the potential for tropical cyclogenesis.

...TROPICAL WAVES...

A tropical wave along 92W north of 07N to Guatemala is moving
west at 10 kt. It is the same tropical wave which spawned TS Ian
in the Atlantic last week. Isolated moderate convection is noted
within 45 nm of the wave axis. 

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

The monsoon trough extends from 09N83W to 09N89W to 15N101W to
low pres near 15N107W to 12N114W to 10N140W. Scattered moderate
convection within 60 nm north of the trough axis west of 130W.

...DISCUSSION...   

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

A ridge extends west of the offshore waters off the coast of
Baja California reaching near the Revillagigedo Islands. The
pressure gradient between this ridge and troughing over the Gulf
of California is maintaining gentle to moderate winds over the
offshore waters of the Baja California Peninsula. There is a
high probability that low pressure southwest of the coast of
Mexico will develop into a tropical cyclone as mentioned above
in the special features section. A gale warning is in affect for
some of the offshore zones in anticipation of the development of
this system. This system is forecast to move west of the Baja
California Peninsula within a few days...and parallel the coast
afterwards.

The tropical wave discussed above will enhance northerly winds
in the Gulf of Tehuantepec during late night and early morning
hours tonight. Winds will continue to pulse the next few days as
high pressure builds over the Gulf of Mexico and tightens the
gradient between the area of high pressure and lower pressure
associated with the monsoon trough. Winds will reach near 25 kt
during the overnight hours.

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

Moderate to occasionally fresh winds are expected north of the
monsoon trough. Gentle to moderate southwest winds are expected
south of the trough axis. Combined seas of 4-6 ft will prevail
in long period cross-equatorial SW swell through mid-week.

REMAINDER OF THE AREA... 

High pressure northwest of the area near 35N147W extends a ridge
southeast to near 19N111W. The gradient between this ridge and
the remnant circulation of Orlene centered near 20N131W supports
20-25 kt winds northwest of the center. The circulation will
weaken to a trough and move west of 140W in about 48 hours. An
altimeter pass earlier today showed seas to 10 north of the low.
Seas will continue to subside during the next two days as the
low disappears and pressure gradient continues to weaken.

$$
Mundell