000
AXPZ20 KNHC 230903
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Wed Aug 23 2023

Tropical Weather Discussion for the eastern Pacific Ocean from
03.4S to 30N, east of 120W including the Gulf of California, and
from the Equator to 30N, between 120W and 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.

...TROPICAL WAVES...

A tropical wave axis is near 101W north of 05N, moving westward 
around 10 kt. Scattered moderate to isolated strong along the 
tropical wave axis over coastal Guerrero, and from 14N to 15N
between 96W and 99W. 

A tropical wave extends from 03N-16N with axis near 117W, moving
westward at 10 to 15 kt. No significant convection is noted near
this tropical wave.

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

The monsoon trough axis extends from 10N84W to 11N125W to 
10N130W. The ITCZ extends from 10N130W to beyond 07N140W. 
Scattered moderate and isolated strong convection is from 11N to
13N between 90W and 92W. Scattered moderate convection is noted 
from 09N to 11N between 111W and 114W.

...OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

A recent scatterometer satellite pass confirmed fresh to strong
N gap winds across the Gulf of Tehuantepec. The gap winds are
occurring due to lowering pressure over the eastern tropical
Pacific, along the monsoon trough. Farther north, an earlier 
ship observation a little south of Punta Eugenia showed NW winds 
at 20 kt, part of a larger area of fresh NW winds off Baja 
California Sur north of Cabo San Lazaro. The scatterometer pass
also showed fresh winds across the central and southern Gulf of
California. These winds are funneling along the coast on the 
eastern edge of the subtropical ridge centered west of the area. 
A weak pressure gradient is supporting gentle breezes elsewhere, 
with moderate combined seas primarily in SW swell. Scattered 
showers and thunderstorms are active along the coast of eastern 
Guerrero state, following a tropical wave moving through the 
area.

For the forecast, the northerly gap winds will continue to pulse
mainly at night across the Gulf of Tehuantepec into Fri. Looking
ahead, a broad area of low pressure is expected to form offshore
of the coast of Central America or southern Mexico during the 
next few days. Environmental conditions appear generally 
favorable for gradual development of this system. A tropical 
depression could form late this week while it moves slowly 
northwest to north- northwest, possibly supporting strong winds 
and rough seas off western Oaxaca Thu night, and off Guerrero and
Michoacan Fri through Sat night. 

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

A small 1009 mb low pressure area is starting develop along the 
monsoon trough west of northwest Costa Rica near 10N87W. Fresh to
strong SW winds are likely ongoing south of the low, with fresh
SE winds across the Gulf of Papagayo and the coast of Nicaragua.
A concurrent altimeter pass indicated combined seas are reaching
8 ft near the coast of Costa Rica and western Panama in a
combination of the fresh SW monsoon flow and a component of
longer-period SW swell. Scattered showers are ongoing in this
area as swell. Gentle breezes and moderate combined seas are
noted elsewhere in SW swell. 

For the forecast, the active monsoon trough will continue to support
fresh to strong SW winds and rough seas off Costa Rica and 
Nicaragua through Thu. Scattered to numerous showers and 
thunderstorms will persist today over the offshore waters from 
Costa Rica to Guatemala. These winds and seas will diminish Fri 
as the monsoon trough lifts north of the area.


...REMAINDER OF THE AREA...

Recent altimeter data indicated seas up to 8 ft near 30N135W,
part of NE swell moving through the area. Farther south, altimeter
data also continues to show 8 ft seas as part of an area 
extending south of 10N and east of 110W, due in part to enhanced 
fresh to strong SW monsoon flow along with a component of SW 
swell. Broad ridging dominates the pattern north of 20N, 
supporting gentle to moderate breezes and moderate combined seas 
in a mix of SW and NW swell. 

For the forecast, fresh to strong SW winds will persist south of
the monsoon trough and east of 120W through Thu. The surface 
ridge should strengthen on Fri into Sun, forcing fresh NE trades 
and seas 6 to 8 ft west of 120W from 10N to 20N.

$$
Christensen