Tropical Weather Discussion

axpz20 knhc 131529

Tropical weather discussion
NWS National Hurricane Center Miami FL
1510 UTC Wed Dec 13 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
1400 UTC.

...Special features...

Gulf of Tehuantepec gale warning: high pressure over eastern
Mexico is helping to produce a tight pressure gradient across 
The Isthmus of Tehuantepec in southern Mexico. The gradient 
supports minimal gale force winds over the Gulf of Tehuantepec, 
as shown in an ascat pass at 0320 UTC. High pressure will shift 
eastward and weaken through tonight, and winds will diminish 
below gale force later today. Winds will continue to decrease on 
Thu. Another brief gale force gap wind event is expected Fri 

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

The monsoon trough extends from 10n84w to 08n88w to 04n93w. The 
ITCZ continues from 04n93w to 09n120w to beyond 10n140w. 
Scattered moderate isolated strong convection is noted from 08n 
to 18n between 112w and 128w, and from 07n to 14n between 128w
and 142w. 


Offshore waters within 250 nm of Mexico...

Gulf of tehuantepec: please see the special features section 
above for details on the ongoing gale wind event. 

Fresh to strong NW winds across the N Gulf of California will 
diminish later today, then strengthen again Thu night through 
Sat. NW swell of 7-9 ft will spread across the waters W of Baja 
California early Fri through Sat night. Otherwise, gentle to 
moderate winds will prevail over the offshore Pacific waters of
Mexico, with seas in the 4-6 ft range.

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

Strong winds will prevail across the Gulf of papagayo through 
early Fri, then strengthen once again Sat night. Moderate to 
fresh N winds will funnel through the Gulf of Panama Thu and Fri.
Mainly gentle to moderate winds and seas of 3-5 ft will prevail
elsewhere over this area the next several days. 

Remainder of the area...

The pressure gradient between high pressure centered north of 
the area and lower pressure in the vicinity of the ITCZ is 
maintaining an area of fresh winds from 10n to 20n W of 125w.
Fresh ESE winds are occurring S of the ITCZ axis W of 135w. These
winds support combined seas of 8 to 10 ft across this area. This
area of winds will persist through Thu, while the swell component
diminishes somewhat. Fresh to strong se winds are occurring N of
28n and W of 138w, to the east of a cold front that is west of 
the area of discussion boundary of 140w. The front will stall and
weaken to the west of our area through Thu which will allow for 
winds to decrease. Meanwhile, large NW swell of 8 to 13 ft will 
propagate out ahead of the front over the NW waters N of 25n and 
W of 135w by this evening. This swell will reach to W of a line 
from 30n125w to 00n140w by Thu night, covering most of our waters
W of 115w Fri night. This batch of swell will subside below 8 ft
late this weekend. On Fri, a trough is forecast to develop just 
W of 140w. The pressure gradient between this trough and high 
pressure north of 30n will support fresh to strong easterly winds
from about 15n to 28n W of 133w Fri through Sat.



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