000
AXPZ20 KNHC 190900
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Wed May 19 2021

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
0830 UTC.

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

The monsoon trough extends westward from 09N78W to 09N110W. The 
ITCZ continues from 09N110W to 09N125W to 08N140W. Scattered 
moderate convection is noted from 06N to 09N between 88W and 
93W. Scattered moderate convection is evident from 06N to 11N 
between 115W and 134W.

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Scatterometer data shows fresh NW winds near the west coast of 
Baja California. Altimeter data indicates seas are 6-7 ft west of
Baja California. Light winds and slight seas prevail over the 
Gulf of California. Farther south, light to gentle W to NW winds 
and 5 to 7 ft seas in SW swell are noted.

For the forecast, fresh NW winds will persist west of Baja 
California Norte through Sun. Seas will increase west of Baja 
California Thu night and Fri as NW swell behind a weak frontal 
boundary moving across southern California reaches the area. 
Meanwhile, long period SW swell will persist over Mexican 
offshore waters into the weekend. A tropical low may form well 
south of the Gulf of Tehuantepec during the next day or two.

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

Xcatterometer data shows light to gentle winds across the 
forecast waters, and altimeter satellite passes indicate seas are
in the 6-8 ft range, in SW swell. The upper level pattern is 
supporting a few showers and thunderstorms along the monsoon 
trough, beyond 180 nm off the coasts of Nicaragua and Costa Rica.

For the forecast, long-period cross equatorial southerly swell 
will continue to impact the offshore forecast waters through Fri 
night, then begin to subside on Sat. Light to gentle winds are
expected to continue through the weekend in the forecast waters. 

REMAINDER OF THE AREA...

The subtropical ridge continues to dominate the waters north of 
15N. The pressure gradient between it and comparatively lower 
pressures in the deep tropics supports a large area of moderate 
to fresh trade winds north of the ITCZ, with seas of 6 to 7 ft. 
Gentle to moderate trade winds are noted elsewhere. 

For the forecast, reinforcing high pressure will allow trade
winds to increase north of the ITCZ and west of 125W, with seas 
building to around 8 ft. 8 to 10 ft seas west of Baja California
will spread westward in the northern forecast waters Thu night
through Sat morning. Seas will continue to be 6 to 7 ft east of
125W. Looking ahead, weak low pressure is expected to form well 
south of the Tehuantepec area by Thu, but not intensify as it 
tracks westward along 10N between 95W and 105W through Sun.

$$
Mundell