000
AXPZ20 KNHC 302128
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2130 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

MONSOON TROUGH AXIS FROM 06N77W TO 06N85W TO 06N98W. ITCZ AXIS 
FROM 06N98W TO 07N117W TO 08N134W TO BEYOND 06N140W. NO 
SIGNIFICANT CONVECTION ALONG THE AXIS. 

...DISCUSSION...
HIGH PRESSURE 1028 MB CENTERED NEAR 33N135W 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 TRADEWINDS OF 20-25 KT 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. THE 
AREA OF WINDS MAY EXPAND SOMEWHAT WESTWARD ON SAT AND CONTINUE 
INTO SUN. 

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 
NORTHERLY WINDS OF 20-25 KT OVER THE GULF OF TEHUANTEPEC SAT
AFTERNOON. WINDS WILL CONTINUE TO INCREASE THROUGH SUN AS A COLD 
FRONT SHIFTS OFF THE TEXAS COAST. GLOBAL MODELS FORECAST WINDS 
REACHING GALE FORCE BY SUN EVENING AND SUGGEST THE POSSIBILITY 
OF STORM FORCE WINDS MON NIGHT INTO TUE. A GALE WARNING WILL 
LIKELY BE ISSUED IN THE 0430 UTC HIGH SEAS FORECAST ISSUANCE 
UNDER AWIPS/WMO HEADERS MIAHSFEP2/FZPN03KNHC. 
     
$$
COBB