Tropical Weather Discussion

axpz20 knhc 200905

Tropical weather discussion
NWS National Hurricane Center Miami FL
1005 UTC Fri Jul 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 0600 UTC surface analysis and satellite imagery through 
0900 UTC. 

...Tropical waves...

A tropical wave is analyzed N of 07n along 101w moving W at 15 
kt. Scattered moderate to strong convection is noted from 08n to 
13n between 98w and 104w.

A tropical wave is analyzed from 04n to 15n along 110w moving W 
at 15 to 20 kt. Scattered moderate convection is noted from 06n 
to 09n between 109w and 114w.

A tropical wave is analyzed from 07n to 16n along 131w moving W 
at 15 to 20 kt. Scattered moderate convection from 09n to 14n 
between 129w and 132w.

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

The monsoon trough extends across the entire basin from 10n90w 
to 10n115w to 13n128w to 11n140w. Scattered moderate isolated 
strong convection is noted along the entire length of the trough 
within 45 nm N and 90 nm S of the convergence axis.


Offshore waters within 250 nm of Mexico...

A surface ridge will persist from 31n134w to the revillagigedo 
islands for the next few days, maintaining gentle to moderate 
breezes across the Mexican offshore waters into early next week. 
Southerly cross-equatorial swell will propagate into the region 
by tonight, allowing seas to build to 5 to 7 ft in open waters 
into early next week. 

In the Gulf of Tehuantepec, strong N gap wind flow will return 
late Sat night, producing mixed seas south of the Gulf as wind 
waves generated near Tehuantepec encounter the longer period 
southerly swell. Gap winds will be due to lower pressure south 
of the region along with localized drainage flow. 

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

Gulf of papagayo: fresh to strong nocturnal easterly winds, 
accompanied by 6 to 8 ft seas, are expected into early next week.

Gentle to moderate easterly winds are forecast elsewhere N of 
the monsoon trough which will meander west of Central America 
between 07n and 10n. Moderate southerly winds are expected S of 
the trough axis the next few days accompanied by 4 to 6 ft seas.

Long period cross-equatorial southerly swell will continue to 
propagate N, reaching the far offshore waters between 05n and 
14n W of 86w Sun night, and the coast of Central America Mon.  

Looking ahead, global models are showing increased southwesterly 
flow into the monsoon trough starting by mid week. This, along 
with strong gap winds through the Gulf of papagayo, will help 
develop multiple low pressure areas along the monsoon trough in 
offshore waters W of Costa Rica and Nicaragua. Expect widespread 
shower and embedded thunderstorm activity in this area after Mon.

Remainder of the area...   

A surface trough will move into the waters north of 27n between 
125w and 135w Fri, and persist into sun. The trough will weaken 
the subtropical ridge, helping maintain moderate to fresh trade 
winds farther south.

Large long period southerly swell is moving across the Equator 
between 90w and 125w, and will continue to propagate northward, 
affecting an area S of 17n between 80w and 133w by Sun night. 

Long period northerly swell will propagate into forecast waters 
N of 27n between 130w and 140w during the upcoming weekend, and 
then subside on Mon.  



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