Tropical Weather Discussion

axpz20 knhc 220358

Tropical weather discussion
NWS National Hurricane Center Miami FL
0405 UTC Thu Nov 22 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 0000 UTC surface analysis and satellite imagery through
0345 UTC.

...Special features...

Gulf of Tehuantepec gale warning: a tightening of the pressure 
gradient across southeastern Mexico has induced minimal gale
force north to northeast winds across the Gulf as of 00z.
Model guidance indicates that these gale force winds will be 
short-lived as they are forecast to diminish back to near gale 
force early on Thu and continue at those speeds through late on 
Thu before diminishing to fresh winds on Fri afternoon and to 
light and variable winds by Fri evening, with little change 
through the upcoming weekend. The next gap wind event across the 
Tehuantepec region is forecast on Mon. Model guidance suggest 
that these winds will reach strong to near gale force late on Mon
of next week and into early on Tue. Seas will build to 11-12 ft 
during the gale force events. Please refer to the east Pacific 
High Seas Forecast under AWIPS/WMO headers hsfep2/fzpn03 knhc for
more details.

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

The monsoon trough axis extends from extreme northwestern
Colombia to 09n79w to 08n92w to 06n103w. The ITCZ axis continues
from 06n103w to 08n120w to 09n132w to 08n140w. Scattered 
moderate convection is within 120 nm north and 60 nm south of 
the ITCZ axis between 113w and 117w. Similar convection is 
within 60 nm south of the monsoon trough axis between 88w and
92w and also between 118w and 125w.


Offshore waters within 250 nm of Mexico... 

See special features section for ongoing Gulf of Tehuantepec 
Gale Warning.

Gulf of california: in the northern portion of the Gulf, light 
and variable winds will remain through tonight. Gentle to 
moderate northwest to north winds will follow in behind a weak 
cold front moving across the area on Thu. In the southern Gulf, 
gentle to moderate NW to N winds will increase to moderate to 
fresh late Thu through Fri night as a high pressure west of the 
Baja California peninsula builds eastward.

Light and variable winds are presently across the offshore 
waters to the west of the Baja California peninsula as a result
of the present rather light gradient there.  A weakening cold 
front is forecast to approach and move across the area on Thu. 
High pressure in the wake of the front will build eastward 
bringing increasing winds and building seas across the waters 
mainly to the north of of 29n by Fri night, and then to the north
of 26n by early on Sat. Wave model guidance suggests NW winds of
20 to 25 kt with building seas of 6 to 9 ft with NW swell.

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

Gulf of papagayo: fresh to locally strong northeast winds with 
seas to 8 ft will diminish Thu afternoon, then return Thu evening 
and diminish Fri afternoon.

The monsoon trough will extend roughly along 08n/09n during the 
next few days with gentle to moderate NE winds N of the trough, 
and moderate to fresh SW winds S of the trough. Seas will be in 
the range of 4 to 6 ft mainly in mixed long-period SW and NW 

Remainder of the area...  

A cold front extends from near 32n121w to 24n135w and is 
dissipating to near 21n140w. Strong high is building east-
southeastward behind it. The main marine hazard with this front
is the extensive area of northwest swell behind it and that is
overspreading the northwest portion of the area. The swell is 
producing seas of 8 to 12 ft in northwest, with the exception of 
higher seas in the 10 to 13 ft range north of 29n. The cold 
front will continue southeastward across the northern forecast 
waters reaching a position from near 32n115w to 28n120w to 
24n125w by Thu morning while gradually weakening and dissipating 
by Fri morning. Swell behind the front will propagate across the 
waters north of about 20n and to the west of a line from 32n115w 
to 20n120w to another line from 32n125w to 24n140w by Fri 
morning and gradually dissipate through Fri night. 

The pressure gradient between high pressure building eastward
across the forecast area and lower pressure in the vicinity of 
the ITCZ will result in fresh to strong trade winds of 20 to 30 
kt and seas of 8 to 11 ft mainly over the waters from 11n to 20n
and west of 122w by late tonight into Thu morning. Similar 
marine conditions are expected by Fri morning. 

An upper-level trough is triggering off scattered moderate 
isolated strong convection from 14n to 19n between 127w and 130w.
Expect for this activity to remain active through Thu as is 
shifts eastward.



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