000
AXPZ20 KNHC 312101
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 UTC Thu Aug 31 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 1800 UTC surface analysis and satellite imagery through
2040 UTC.

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

The monsoon trough axis extends from Panama near 09N78W to 12N95W
to 12N110W to 06N124W. The ITCZ continues from 06N124 to 09N133W. 
Scattered moderate isolated strong convection is evident from 
02N to 09N between 77W and 99W, including over portions of Panama
and Costa Rica. Scattered moderate convection is noted from 04N 
to 20N between 99W and 119W.

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

A broad surface trough extends from 16N116W to 1008 mb low 
pressure near 21N114W to 24.5N112W. Upper-level diffluence is 
enhancing scattered moderate convection on both sides of Baja 
California Sur, near the entrance to the Gulf of California, and 
offshore southwestern Mexico. Mainly gentle winds dominate the 
offshore waters of Mexico, except in the northern Gulf of 
California, where a recent ASCAT satellite data pass shows fresh
SSE winds. Seas are 5-7 ft offshore Baja California, 4-5 ft in
the northern Gulf of California, 2-3 ft elsewhere in the Gulf,
and 5-6 ft elsewhere off Mexico in S swell.

For the forecast, pulsing fresh to strong S winds will continue
in the northern Gulf of California through Fri night. Fresh to 
strong northerly winds will pulse in the Gulf of Tehuantepec Fri 
night through Sat night. Winds will be moderate or weaker 
elsewhere through Sat. Winds will increase to fresh nearshore 
Baja California Sun night through Mon night as the pressure 
gradient tightens along the peninsula.

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

Light to gentle winds prevail across the offshore waters N of 
05N, except for moderate NE to E winds in the Papagayo region,
and stronger gusts possible in thunderstorm activity near Panama
and southeastern Costa Rica. Seas north of 05N are 5-7 ft in 
long-period south to southwest swell. To the south of 05N, 
including the waters offshore southern Colombia and in between 
Ecuador and the Galapagos Islands, moderate S winds with seas of 
7-9 ft are present due to long-period S to SW swell. Those winds
and seas were confirmed by recent ASCAT and altimeter passes,
respectively. Scattered tstms are noted off Colombia, Panama and
SE Costa Rica ahead of a tropical wave currently over the 
S-central Caribbean Sea and central Colombia.

For the forecast, moderate to locally fresh south to southwest 
winds will continue between the coast of Ecuador and the 
Galapagos Islands most of the time through the weekend. Southerly
swell of 7-9 ft will subside only slightly this evening. Then, 
renewed long period S to SW swell will move through those waters 
Fri into Sat, increasing seas back to 8-9 ft through early Sun. 
Swell of 6-8 ft will reach the waters offshore Panama and Costa 
Rica late Sat through late Sun. Elsewhere, light to gentle 
variable winds will prevail through most of the the forecast, 
locally and occasionally moderate to fresh near the Gulfs of 
Papagayo and Fonseca, along with slight to moderate seas in long-
period SW swell. Enhanced showers and thunderstorms will continue 
off Panama and Costa Rica through tonight.

...REMAINDER OF THE AREA...

The post-tropical remnant low of former Tropical Cyclone Irwin 
is centered near 19.5N137.5W with an estimated central pressure 
of 1009 mb. It is moving westward at 5 to 10 kt. A tight 
pressure gradient between the low and strong high pressure to its
north is keeping strong to near gale force winds in the 
northwest semicircle from the low to 25N between 136W and 140W. 
Seas are 10-13 ft in this area. Convection has waned during the
past 6 hr, and now only isolated showers are occurring with the
low. Elsewhere north of 20N and west of 123W, fresh N to NE 
winds and 8 to 10 ft seas prevail. Winds are mainly moderate or 
weaker across the remainder of the open waters, with seas 6-8 ft.
A broad surface trough extends from 16N116W to 1008 mb low 
pressure near 21N114W to 24.5N112W. Upper-level diffluence is 
enhancing showers and tstorms east of the trough axis.

For the forecast, the post-tropical remnant low of Irwin will 
continue moving westward, with a slightly slower motion expected,
reaching 140W on Fri. Fresh to strong winds and elevated seas 
will continue to accompany the low, mainly in the NW semicircle. 
Elsewhere, northerly swell will propagate through the open waters
well W of Baja California through early Fri, keeping seas of 
6-10 ft N of 20N and W of 120W. Southerly swell of 7-9 ft in the
far southern waters to the south of 06N will only subside
slightly this evening. Another long period S swell event will 
push northward across the Equator late tonight and Fri with seas 
of 8-9 ft south of 06N and east of 120W into Sat before 
subsiding late in the weekend. The broad north-south oriented 
surface trough with accompanying low pressure is expected to move
from along 114W to 120W by the weekend, resulting in shifting 
winds.

$$
Hagen