000
AXPZ20 KNHC 301532
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI DEC 30 2011

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...

THE MONSOON TROUGH AXIS EXTENDS FROM 09N84W TO 05N103W. THE ITCZ 
AXIS EXTENDS FROM 05N103W TO 09N133W TO BEYOND 05N140W. NO 
SIGNIFICANT CONVECTION WAS NOTED NEAR THE AXIS.

...DISCUSSION...
HIGH PRESSURE 1026 MB CENTERED NEAR 33N137W WITH RIDGE EXTENDING 
SE TO NEAR 20N111W. THE PRESSURE GRADIENT BETWEEN THIS FEATURE 
AND LOWER PRESSURE IN THE VICINITY OF THE ITCZ IS MAINTAINING 
FRESH TRADEWIND FLOW FROM 10N TO 20N W OF 130W. THE AREA OF HIGH 
PRESSURE WILL WEAKEN THROUGH SUN MORNING ENABLING A COLD FRONT 
TO APPROACH THE NW PART OF THE AREA. WITH HIGH PRESSURE 
WEAKENING...THE AREAL COVERAGE OF FRESH 20 KT TRADEWINDS WILL 
DECREASE...AND TRADES WILL DIMINISH BELOW 20 KT BY SUN MORNING. 
S TO SW WINDS WILL INCREASE OVER THE FAR NW PART OF THE AREA 
AHEAD OF THE COLD FRONT WHICH IS EXPECTED TO MOVE INTO THE 
FORECAST AREA ON SUN. 

GULF OF PAPAGAYO...
FRESH TO STRONG TRADEWINDS FROM THE WESTERN CARIBBEAN CONTINUE 
TO FLOW THROUGH THE CENTRAL AMERICA GAPS INTO THE GULF OF 
PAPAGAYO. WINDS WILL PEAK DURING THE EARLY MORNING HOURS WITH 
THE ADDED COMPONENT OF NOCTURNALLY DRIVEN KATABATIC WINDS. 

GULF OF TEHUANTEPEC...
TROUGHING WILL SET UP OVERNIGHT OVER THE YUCATAN PENINSULA WITH 
HIGH PRESSURE PREVAILING OVER EASTERN MEXICO. THE PRESSURE 
GRADIENT BETWEEN THESE FEATURES...AND RESULTING LOCALLY 
INCREASED WINDS WILL FUNNEL THROUGH THE CHIVELA PASS INTO THE 
GULF OF TEHUANTEPEC OVERNIGHT. THIS WILL RESULT IN FRESH TO 
STRONG WINDS OVER THE GULF OF TEHUANTEPEC BY SAT MORNING. WINDS 
WILL CONTINUE TO INCREASE THROUGH SUN AS A COLD FRONT SHIFTS OFF 
THE TEXAS COAST. WINDS MAY REACH GALE FORCE BY SUN EVENING.     

$$
AL