000
AXPZ20 KNHC 192136
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC WED DEC 19 2012

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH EXTENDS FROM 07N78W TO 08N85W TO 07W90W THEN ITCZ 
CONTINUES TO 08N108W TO 08N130W TO 07N140W. SCATTERED MODERATE 
FROM 06N TO 09N BETWEEN 119W AND 125W.

...DISCUSSION...
THE STRONG HIGH PRESSURE LOCATED N OF AREA HAS WEAKENED AND NOW 
IS CENTERED NEAR 33N127W WITH SURFACE RIDGE EXTENDING SE TO NEAR 
20N110W. A COLD FRONT EXTENDS ACROSS NW MEXICO AND SOUTHERN BAJA 
CALIFORNIA NEAR 26N112W TO 22N122W. THE PRESSURE GRADIENT 
BETWEEN THESE FEATURES IS SUPPORTING FRESH TO STRONG N TO NE 
WINDS N OF THE FRONT. NW SWELLS CONTINUE TO SPREAD S AND E 
ACROSS THE FORECAST AREA...WITH COMBINED SEAS NEAR 13 FT W OF 
NORTHERN BAJA CALIFORNIA TO ABOUT 125W. THE PRESSURE GRADIENT 
BETWEEN THE RIDGE AND LOWER PRESSURE IN THE VICINITY OF THE ITCZ 
IS MAINTAINING AN AREA OF FRESH TO STRONG TRADEWINDS FROM 08N TO 
20N W OF 130W 

THE HIGH PRESSURE CENTER WILL SHIFT SE TO A POSITION JUST N OF 
THE FORECAST AREA NEAR 31N122W WHILE THE COLD FRONT WILL 
DISSIPATE OVER THE NEXT 24 HOURS. THE PRESSURE GRADIENT WILL 
RELAX AND WINDS WILL DIMINISH BELOW 25 KT BY THU MORNING. THE 
AREA OF TRADE WINDS WILL ALSO SHRINK BY THU MORNING WITH THE 
STRONGEST WINDS W OF 140W. THE NW SWELL WILL CONTINUE TO SPREAD 
S AND E WHILE CONTINUING TO SUBSIDE...WITH SEAS OF 8 TO 10 FT 
COVERING THE AREA FROM 08N TO 20N W OF 115W BY LATE FRI. 

A SECOND COLD FRONT WILL REACH 30N140W THU AFTERNOON AND EXTEND 
FROM 30N130W TO 25N140W FRI AFTERNOON. WINDS BEHIND THE FRONT 
WILL REMAIN BELOW ADVISORY CRITERIA. THIS FRONT WILL USHER IN A 
FRESH SET OF NW SWELLS INTO THE AREA. SEAS WILL REACH NEAR 16 FT 
OVER THE FAR NW PART OF THE AREA BY EARLY FRI...AND WILL PEAK 
NEAR 19 FT BY FRI AFTERNOON BEFORE STARTING TO SLOWLY SUBSIDE.  
 
GAP WINDS...
A COLD FRONT WILL SHIFT RAPIDLY ACROSS THE GULF OF MEXICO ON 
THU. WINDS BEHIND THIS FRONT WILL FUNNEL THROUGH THE CHIVELA 
PASS INTO THE GULF OF TEHUANTEPEC WHICH WILL LEAD TO A STRONG 
GAP WIND EVENT. STRONG NORTHERLY WINDS WILL START TO FUNNEL INTO 
THE GULF OF TEHUANTEPEC BY THU EVENING AND WILL RAPIDLY INCREASE 
TO STORM FORCE BY EARLY FRI. A STORM WARNING IS ALREADY IN 
EFFECT FOR THIS AREA. 

WINDS WILL ALSO INCREASE ACROSS THE GULF OF PAPAGAYO BY FRI. 
EXPECT NE TO E WINDS OF 20-30 KT AND SEAS OF 8-10 FT IN AND 
DOWNSTREAM OF THE GULF TO ABOUT 92W BY SAT MORNING.

$$
GR