AXPZ20 KNHC 120928
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Sat Sep 12 2020

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
0830 UTC.

...SPECIAL FEATURES...

A 1006 mb low is centered along the monsoon trough near
15.5N109.5W, and anchors the eastern end of an elongated
cyclonic circulation in the lower atmosphere that extends W-NW to
a second surface low of 1009 mb near 17.5N118.5W. A large area
of active weather is persisting south and west of the 1006 mb,
where scattered moderate to strong convection is occurring from
09N to 19.5N between 107W and 119W. Recent ASCAT data depicted a
very broad cyclonic circulation about the low between 104W and
113W with peak winds around 20 kt and seas 6-7 ft between the
low and the coast of western Guerrero. Strong westerly monsoonal
winds of 20 to 30 kt were depicted south of the low and the
monsoon trough between 108W and 119W, where seas are 7-9 ft.
Environmental conditions appear conducive for development of this
system, and a tropical depression is likely to form over the
weekend or early next week while the system moves west-
northwestward away from the coast of Mexico. The system has a
high chance of developing over the next two days. For more
information, see the latest Tropical Weather Outlook at
https://hurricanes.gov.

...TROPICAL WAVES...

A tropical wave extends along 87W north of 03N to across Central
America, moving westward at 10-15 kt. Scattered moderate to
strong convection ahead of the wave has been occurring over land
and is shifting over water, extending from 10N to the coast
between 84W and 96W.

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

The monsoon trough axis extends from 10.5N73W to 09N83W to low
pres near 15.5N109.5W 1006 MB to low pres near 17.5N118.5W 1009
MB to 11N140W. Scattered moderate isolated strong convection is
noted N of 06N between 78W and 85W. Scattered moderate to strong
convection is noted from 07N to 14N between 87W and 96W, from
08N to 11N between 100W and 104W, from 09N to 19.5N between 107W
and 119W. Scattered moderate isolated strong convection is noted
from 11N to 14N between 119W and 140W. Scattered moderate
isolated strong convection is within 180 nm across the NW
semicircle of low pressure 1009 mb near 18.5N118.5W.

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

See Special Feature discussion of low near 14N107W.

Generally tranquil marine conditions are expected across the
offshore waters for the next several days as a weak pressure
gradient prevails. However, the low pressure near 15.5N109.5W is
expected to gradually become better organized and will increase
winds and seas across the outer waters from offshore of
Manzanillo and Cabo Corrientes, shifting west-northwest to the
Clarion Island area through the weekend.

Modest pulses of northerly gap winds to near 20 kt can be
expected each of the next few nights across the Gulf of
Tehuantepec, increasing seas to 6 ft.

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

Tranquil conditions should prevail for the next several days
with light to gentle winds north of the monsoon trough along
about 10N, and gentle to moderate south to southwest winds south
of the monsoon trough. No significant long-period swell is
expected to impact these waters during the next several days,
although small swell will continue to impact the waters for the
next several days.

REMAINDER OF THE AREA...

Low pressure of 1009 mb is centered southwest of the Clarion
Island near 17.5N118.5W. Scattered moderate to strong convection
is within 180 nm of the low in the NW quadrant. Recent ASCAT
data indicated a broad and weak cyclonic circulation consisting
of gentle to moderate winds across the east semicircle and 15-20
kt winds within about 210 nm of the low in the western
semicircle. Some development of this system is possible during
the next few days before it interacts with, and possibly becomes
absorbed by the larger weather disturbance to its east discussed
in the Special Feature section.

High pressure of 1021 mb centered near 31N131W dominates the
waters north of 20N, west of 120W. Gentle to moderate northeast
trades continue north of the monsoon trough axis with seas 5-7
feet. Moderate to fresh south flow persists south of the trough
with 5-7 ft seas. Long-period south to southwest swell is
present east of 120W, contributing to combined seas of 7-8 feet
near the equator. Seas will subside slightly through Tue, however
wave model guidance suggests that new south to southwest will be
moving through waters south of the Equator and east of 120W
during the early to middle part of next week.

$$
Stripling
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