000
AXPZ20 KNHC 162200
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI DEC 16 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 
2100 UTC.

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

MONSOON TROUGH AXIS FROM 10N85W TO 08N91W TO 08N101W THEN ITCZ 
TO 08N132W TO BEYOND 07N140W.  ISOLATED MODERATE CONVECTION 
WITHIN 45 NM OF AXIS FROM 104W TO 116W.  SCATTERED MODERATE 
CONVECTION WITHIN 90 NM OF AXIS W OF 130W.

...DISCUSSION...

WELL DEFINED UPPER LEVEL CYCLONE AT 31N116W REFLECT AS HEALTHY 
SURFACE LOW PRES 1016 MB WITH FRONTAL TROUGH EXTENDING SW TO 
24N120W THEN W TO 24N127W.  CYCLONE MOVES E-NE SAT ONLY TO BE 
REPLACED BY NEW CYCLONE FROM THE NW WITH ITS ATTENDANT FRONTAL 
BOUNDARY LATE SUN.  MID TO UPPER LEVEL RIDGE REMAINS WELL N AND 
W OF BASIN ALLOWING SERIES OF SHORT WAVES TO IMPACT NE PORTION 
OF E PAC.  MOISTURE LADEN AIR MASS FLOWS INTO BASIN FROM THE W 
ALONG ITCZ WITH SOME FLARE UPS W OF 130W AS UPPER DIVERGENCE 
ENHANCES CONVECTION. 

UPPER LEVEL RIDGE OVER SOUTH AMERICA ADVECTS ABUNDANT MOISTURE 
ALONG MONSOON TROUGH BUT LACKS MECHANICAL UPLIFT TO WARRANT 
SIGNIFICANT CONVECTION.  ONLY ISOLATED SHOWERS ELSEWHERE ALONG 
ITCZ.    

ELSEWHERE AT THE LOW LEVELS...
HIGH PRES CENTER 1031 MB N OF BASIN PRODUCING FRESH NE BREEZE W 
OF 130W WEAKENS IN STRENGTH AND SHRINKS IN COVERAGE AS FRONTAL 
BOUNDARIES SCRATCH NE PORTION OF E PAC SAT AND SUN.

GAP WINDS...
GULF OF TEHUANTEPEC...MODEL GUIDANCE AGREE ON BRINGING STRONG N 
WINDS ACROSS CHIVELA PASS UNTO GULF OF TEHUANTEPEC BY SAT NIGHT
...TURNING INTO GALE FORCE WINDS ACROSS GULF OF TEHUANTEPEC.  
EVENT IS SHORT LIVED AS WIND SOURCE IS QUICKLY CUT OFF BY FAST 
MOVING HIGH PRES RIDGE OVER CONUS ATLC SEABOARD.  FRESH TO 
STRONG N WINDS BEGIN TONIGHT PRECEDING GALE. 

GULF OF PAPAGAYO...BUILDING PRES GRADIENT OVER SOUTHERN MEXICO 
EXTEND S TO GULF OF PAPAGAYO EARLY SAT WITH FRESH NE WINDS 
EXPECTED TO INCREASE EARLY SUN AND EXTEND N ALONG NICARAGUAN 
COAST TO GULF OF FONSECA.

$$
WALLY BARNES