000
AXPZ20 KNHC 301508
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1500 UTC Sun Dec 30 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 1200 UTC surface analysis and satellite imagery through
1500 UTC.

.INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 

A surface trough extends from 06N78W to 04.5N92W. The ITCZ 
continues from 04.5N92W to 04N123W to beyond 08N140W. Scattered 
moderate isolated strong convection is noted from 09N to 11N
between 110W and 118W. Scattered moderate convection is noted
within 60 nm either side of the ITCZ W of 125W. 

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO... 

Subsiding northerly swell is propagating across the offshore 
waters of Baja California, with seas in the 5-8 ft range. Seas 
will subside to 5-7 ft by this afternoon. Another pulse of 
northerly swell will propagate into the waters off Baja 
California Norte tonight, building seas to near 10 ft Mon. Seas 
will then subside through midweek.

Gulf of California: High pressure will build over the Great 
Basin of United States by midweek, supporting strengthening 
winds over the Gulf of California Tue through Thu.

Gulf of Tehuantepec: A strong gap wind event is expected late 
next week. Winds will strengthen across the gulf Tue night, and 
further increase to gale force Thu morning. 

OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND 
WITHIN 750 NM OF ECUADOR... 

Fresh to strong NE to E winds are expected across and downstream
of the Gulf of Papagayo through Thu. Winds will peak during the 
overnight and early morning hours with the assistance of 
nocturnal drainage flow. Moderate to fresh N winds are expected 
across the Gulf of Panama through Thu, pulsing to strong during 
the overnight hours. Elsewhere, gentle to moderate NE winds will 
prevail N of 08N, while gentle to moderate southerly winds are 
expected S of 08N. 
  
REMAINDER OF THE AREA...  

High pressure of 1035 mb centered N of the area near 36N134W 
extends a ridge across the forecast waters to beyond the 
Revillagigedo Islands to near 16N108W. The pressure gradient 
between this area of high pressure and lower pressure in the 
vicinity of the ITCZ is supporting fresh to strong tradewinds N 
of the ITCZ to near 23N and W of 116W. The area of high pressure 
will remain in place N of the area helping to maintain this broad
area of fresh to strong trades. Long period NW swell is merging 
with this tradewind swell to produce seas of 8 to 13 ft over much
of the area north of the ITCZ west of 120W. 

Global models continue to indicate a cold-core upper low will 
dig into the base of a mid/upper level trough early next week, 
supporting the development of a sharp surface trough or even 
weak low pressure along the ITCZ near 120W by mid week. This 
will likely enhance the trade winds north of the ITCZ and west 
of 120W, with near gale conditions possible on the northern end 
of the surface trough.

$$
AL