000
AXPZ20 KNHC 201535
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU DEC 20 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM 05N77W TO 07N100W THEN ITCZ TO 
BEYOND 08N140W. THERE NO SIGNIFICANT CONVECTION ASSOCIATED WITH 
THE CONVERGENCE ZONE BOUNDARY.

...DISCUSSION...
A COLD FRONT EXTENDING FROM THE ORE/CAL BORDER TO AROUND 30N147W 
WILL MOVE SLOWLY SE AND WEAKEN THROUGH FRI NIGHT...EXTENDING FROM
THE COAST OF CENTRAL CALIFORNIA TO NEAR 27N133W BY EARLY SAT. 
LARGE NW SWELL ASSOCIATED WITH THIS FRONT WILL SWEEP ACROSS THE 
NW PORTION OF THE DISCUSSION AREA THROUGH SAT...WITH COMBINED 
SEAS BUILDING TO 18-20 FT ALONG THE NORTHERN BOUNDARY W OF 130W 
FRI AND SAT. TRADE WINDS ACROSS THE AREA OF LARGE SWELL WILL BE 
GENERALLY NE AT 10-20 KT. HIGH PRES WILL BUILD EASTWARD BEHIND 
THE FRONT ALONG 26N THROUGH MON NIGHT. THE HIGH WILL BECOME THE 
DOMINANT SYNOPTIC FEATURE ACROSS THE REGION SAT THROUGH TUE... 
WITH LIGHT WINDS AND SEAS SUBSIDING FROM 15-17 FT TO 8-10 FT N 
OF 22N BY CHRISTMAS DAY. THE HIGH WILL ALSO ENHANCE E-NE TRADE 
WINDS S OF THE RIDGE AXIS AND N OF THE CONVERGENCE ZONE. EXPECT 
FRESH TO STRONG TRADE WINDS BETWEEN 09N AND 20N W OF 120W SUN 
THROUGH TUE. GENTLE TO MODERATE WINDS WILL PREVAIL ELSEWHERE.

GAP WINDS...
STRONG HIGH PRES BEHIND A FAST-MOVING COLD FRONT MOVING OFF THE 
TEXAS COAST INTO THE GULF OF MEXICO WILL INDUCE A SUDDEN INCREASE
IN GAP WINDS THROUGH CHIVELA PASS INTO THE GULF OF TEHUANTEPEC 
WITHIN THE NEXT 12-15 HOURS. WINDS WILL SUDDENLY AND DANGEROUSLY 
SURGE FROM NEAR CALM CONDITIONS AHEAD OF THE COLD FRONT TO GALE 
FORCE CONDITIONS WITHIN MINUTES...THEN CONTINUE TO BUILD TO STORM
FORCE TONIGHT. SEAS WILL RAPIDLY BUILD IN EXCESS OF 15-20 FT IN 
BY FRI MORNING. GFS MODEL GUIDANCE INDICATES STORM FORCE WINDS 
WILL PERSIST TONIGHT THROUGH EARLY SAT...WITH GALE CONDITIONS 
CONTINUING THROUGH SUN MORNING. WIND-DRIVEN SEAS WILL FAN OUTWARD
FROM THE SOURCE REGION AS N-NE SWELL EXTENDING DOWNWIND FROM THE 
GULF OF TEHUANTEPEC TO 110W...MERGING WITH NW SWELL FROM THE COLD
FRONT MENTIONED EARLIER.

WINDS ACROSS THE GULF OF PAPAGAYO CONTINUE TO PULSE TO 20 KT AT 
NIGHT INTO EARLY MORNING HOURS FROM NOCTURNAL DRAINAGE FLOW. AS 
THE TRADE WIND FLOW INCREASES ACROSS THE SW CARIBBEAN BY FRI... 
EXPECT NE TO E WINDS OF 20-30 KT AND SEAS BUILDING TO NEAR 12 FT 
IN AND DOWNSTREAM OF THE GULF OF PAPAGAYO BY SAT AFTERNOON.

$$
MUNDELL