Tropical Weather Discussion

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axpz20 knhc 220323
twdep 

Tropical weather discussion
NWS National Hurricane Center Miami FL
0405 UTC Wed Nov 22 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 0000 UTC surface analysis and satellite imagery through
0315 UTC.

...Special feature...

Gulf of Tehuantepec gale warning: gale force winds are expected 
to develop rapidly late Wed afternoon, as a cold front moves 
quickly southward across Mexico and the western Gulf of Mexico. 
Light winds across the Tehuantepec region Wed morning and 
afternoon with quickly increase to 20-25 kt by mid-afternoon and 
then blast 30-40 kt by late afternoon into the evening hours, and
continue through Thu morning. Minimal gale force winds will persist
through Fri morning. Expect seas to build to 14 to 17 ft near 
14.5n95.5w by late Thu. The resultant NE swell will propagate SW,
mixing with long-period cross equatorial swell, with seas 8 ft 
or higher across the waters well downstream of the Gulf of 
Tehuantepec, roughly within 120 nm of line from 12n97w to 07n100w
early Fri before beginning to subside. 

Intertropical convergence zone/monsoon trough... 

The eastern Pacific monsoonal circulation has weakened in recent 
days with the monsoon trough currently extending from the semi-
permanent low pressure near 10n75w across Panama on to 08n96w. 
The ITCZ then begins from 08n96w to 08n110w to 10n130w. Scattered
moderate to strong convection is noted generally from 10n to 15n
and W of 136w...and within 60 nm of 14n132.5w.

 
...Discussion...

Offshore waters within 250 nm of Mexico...

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

A weak NW to se orientated ridge extends from a 1019 mb surface 
high near 31n124w across the waters just beyond 250 nm seaward 
of the Baja Peninsula and will maintain light to moderate NW 
winds across the offshore waters N of 20n through early Wed. 
A weak trough is expected to form extending SW from the central 
Baja Peninsula to near 23n116w, and continue through early Fri 
before filling. This will occur as the ridge shifts slightly NW 
and act to weaken weaken winds through the week, with light to 
gentle winds prevailing. Expect seas in the 3 to 4 ft range 
through Thu, building to 4 to 7 ft across the waters N of 25n 
late in the week.

Gulf of california: moderate to fresh NW winds are ongoing at 20
to 25 kt and should gradually subside by early Wed. Seas are 
expected to peak at around 5-7 ft through central portions tonight.
The pressure gradient will relax Thu and Fri, with light and 
variable winds expected through sun. 

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

  
Gulf of papagayo: light drainage flow expected during the 
overnight hours through Thu, with fresh to locally strong 
nocturnal drainage beginning on Fri and continuing through the 
upcoming weekend.

Light and variable winds, and 3 to 5 ft seas, are expected 
elsewhere to the N of the monsoon trough which has been 
meandering between 09n and 11n, while moderate to locally fresh 
southerly winds, and 3 to 6 ft seas, are forecast S of the 
monsoon trough through the upcoming weekend.  

Remainder of the area... a NE to SW aligned ridge will meander 
from 32n125w to 22n137w for the next several days. Fresh southerly
winds, currently across the NW waters will diminish to less than 
20 kt on Wed as the ridge weakens allowing a reinforcing cold 
front to approach the far NW portion the area Wed and stall near 
the NW corner Thu. Long period NW swell, in the form of 12 to 15 
ft seas at 13 to 15 seconds, will propagate E into the far NW 
portion of the area Wed night and generally NW of a line from 
30n122w to 15n140w by Thu night with seas subsiding to 8 to 12 
ft.

  
$$
Cobb


		
		

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