Tropical Weather Discussion

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twdep 

Tropical weather discussion 
NWS National Hurricane Center Miami FL
1605 UTC Thu Nov 23 2017

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 1200 UTC surface analysis and satellite imagery through 
1515 UTC.

...Special feature...

Gulf of Tehuantepec gale warning: 30 to 40 kt northerly winds 
continue across the Gulf of Tehuantepec and downstream to near 
13n96w this morning, and will gradually shrink and in areal 
coverage to minimal gale conditions tonight through mid morning 
on Fri. Winds will then diminish to 20 kt or less late Sat 
morning. Maximum seas of 16-17 ft near 14n95.5w area occurring 
this morning and will subside very slowly through tonight to 
around 12-13 ft. The resultant NE swell will propagate SW, 
mixing with long- period cross equatorial swell, with seas 8 ft 
or higher well downstream of the Gulf of Tehuantepec along 08n 
between 95w and 105w on Fri night before beginning to subside. 
Expect winds 20 kt or less and seas less than 8 ft only briefly 
on Sat afternoon. Strong N winds are forecast to resume again on 
Sat evening with gale conditions expected just after sunrise on 
sun. Latest guidance is suggesting another 30 to 40 kt event on 
Sun night with the gales diminishing late Mon.

Intertropical convergence zone/monsoon trough... 

The monsoon trough extends from NW Colombia near 10.5n75w across 
Costa Rica to near 10n87.5w to 09.5n108w. The ITCZ begins near 
10n115w to 07n137w to beyond 07.5n140w. Scattered moderate 
isolated strong convection is seen NE of a line from 04n77w to 
09n85w to the coasts. Scattered moderate to strong convection is 
occurring within 150 nm N and 60 nm S of the ITCZ between 115w 
and 119w, and between 133.5w and 139w.

...Discussion...

Offshore waters within 250 nm of Mexico...

See special features paragraph above for information on the 
Gulf of Tehuantepec Gale Warning. 

A modest high pressure ridge centered offshore of Southern 
California has weakened locally overnight and is yielding gentle 
and variable winds with seas of 2 to 4 ft across the offshore 
waters of baja this morning and are expected to continue today. 
Seas will begin to build Fri afternoon in NW swell, and peak at 
4 to 7 ft at 13 to 15 seconds across the waters W of baja Fri 
night, then subsiding some on Sat into sun. Long-period NW swell 
in the form of 7 to 9 ft seas will reach 30n120w on Sun night, 
and spread S across the waters W of baja with 8 to 13 ft seas at 
17 to 19 seconds forecast W of baja Mon night and Tue.

Gulf of california: moderate NW flow prevails across all but far 
southern portions of the Gulf this morning and will continue 
through tonight. The pressure gradient will then relax, with 
light and variable winds expected Fri through Mon. Strong to 
near gale force NW flow is expected to develop N of 25n on Mon 
night through Tue night, with seas building to 12 ft across the 
long fetch waters.  

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

  
Gulf of fonseca...fresh NW winds forecast to begin around 
sunrise on Mon.  

Gulf of papagayo: fresh to locally strong NE nocturnal drainage 
flow forecast to begin late this afternoon into tonight, with 
strong pulses through Tue. Seas of 8 ft or greater will 
propagate SW to neat 08n92w on Tue.

Light and variable winds, and 3 to 5 ft seas, are expected 
elsewhere through Sun night to the N of the monsoon trough which 
has been meandering between 09n and 11n.  Moderate NE flow 
expected N of the Gulf of papagayo early Mon. Moderate southerly 
winds, and 3 to 6 ft seas, are forecast S of the monsoon trough.

Remainder of the area... 

A cold front from 30n138.5w to 28n140w will stall today with a 
broad surface low developing along the front near 30n140w 
tonight. The low will move NE of the area on Fri night with the 
front then moving se to extend from 30n138w to 26n140w Sat 
morning. Scattered moderate to strong convection is observed 
E of the front from 15.5n to 27.5n between 137w and 142w.

Combined seas of 8 to 15 ft at 14 to 16 seconds is currently 
observed across the discussion waters W of a line from 30n129w 
to 21.5n140w. This long period NW swell will propagate across 
the waters W of a line from 32n122w to 12n137w early Fri before 
beginning to subside. 

Another cold front will move E in to the area reaching from 
32n133w to 23n140w on Sat with 9 to 12 ft seas at 12 to 17 
seconds in the wake of the front.   

  
$$
Stripling


		
		

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