Tropical Weather Discussion

axpz20 knhc 202135

Tropical weather discussion
NWS National Hurricane Center Miami FL
2205 UTC Mon Aug 20 2018

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 
2000 UTC. 

...Tropical waves...

A tropical wave along 93w is moving W 15-20 kt. Satellite 
imagery suggests two short amplitude waves are moving through 
this region between 83w and 102w and reorganizing. Widely 
scattered moderate to strong convection is from 06n to the 
Mexican coast along 16n between 86w and 100w. 

A tropical wave along 112w-113w is moving W around 15 kt. Widely 
scattered moderate to strong convection is found from 07n to 
17n between 110w and 120w.

A tropical wave along 128w-129w is moving W around 15 kt. Widely 
scattered moderate to strong convection is found from 07n to 
18n between 120w and 132w.

...Intertropical convergence zone/monsoon trough... 

The monsoon trough extends from low pres 1010 mb near 09n74w and 
meanders WNW to near 13n123w to 10n140w, where it terminates. 
Scattered moderate to strong convection is seen from 07n to 11n 
between 100w and 106w, from 13n to 16n between 133w and 139w, 
and from 07n to 10n between 132w and 140w.


Offshore waters within 250 nm of Mexico... 

A surface ridge across the NE Pacific is centered on a 1032 mb 
high near 46n138w and extends S and se, entering the forecast 
waters near 30n131w, then extends se to just beyond the 
revillagigedo islands. This ridge will support a weak to modest 
pressure gradient across the offshore waters of Baja California, 
to produce gentle to moderate NW winds through Wed before the 
ridge strengthens modestly and the pressure gradient tightens 
across Baja California norte Thu and Fri. Seas will generally 
remain in the 4-5 ft range through Wed. Surface troughing over 
the Baja Peninsula will maintain a generally light wind regime 
over the Gulf of California through Fri night, and allow for 
afternoon sea breezes and nocturnal land breezes to dominate.

Strong N to NE gap winds will affect the Gulf of Tehuantepec Tue 
night through Thu night, and are forecast to peak near 30 kt 
late Wed night. Seas of 4 to 6 ft during the daytime could build 
to near 8 ft each of these nights, and 8-10 ft late Wed night.

Offshore waters within 250 nm of Central America, Colombia, and 
within 750 nm of Ecuador...

The monsoon trough will linger near 09n during the next few 
days. Winds on both sides of the trough axis will generally be 
light to moderate. The main exception to this will be over the 
Gulf of papagayo, where moderate to fresh offshore winds will 
pulse to locally strong each night. Seas are expected to remain 
6-7 ft downstream of papagayo during this time.

Remainder of the area...   

Elsewhere, the pressure gradient between ridging across the 
northern waters and the ITCZ will support gentle to moderate 
trades and 4-7 ft seas in mixed swell N of the ITCZ and W of 
120w through the middle of this week.

Sea heights will be relatively low for most of the forecast area 
this week. Mixed se and SW swell has produced seas S of 01s and 
W of 105w to briefly build to 8 ft this morning and will 
continue through Tue morning before subsiding to less than 8 ft. 
A much more robust round of long period swell could arrive from 
the southern hemisphere toward the end of this week and cause 
seas near the Equator to begin building on Sat.



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