000
AXPZ20 KNHC 312156
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SAT DEC 31 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 
2115 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH AXIS FROM 07N75W TO 04.5N79W TO 06N86W TO 
04.5N92W...WHERE IT TRANSITIONS TO ITCZ...CONTINUING ON TO  
04N97W TO 06N107W TO 07N123W TO BEYOND 06.5N140W. SCATTERED 
MODERATE TO STRONG WITHIN 90 NM OF AXIS FROM 113W TO 130W.

...DISCUSSION...
THE AREA OF HIGH PRESSURE THAT HAD BEEN CENTERED N OF THE AREA 
HAS WEAKENED SIGNIFICANTLY...WITH THE PRIMARY HIGH PRESSURE 1026 
MB CENTERED FURTHER N NEAR 38N126W. WITH THIS AREA OF HIGH 
PRESSURE WEAKENING...THE AREA OF FRESH TRADEWINDS ARE NOW 
LIMITED TO THE AREA FROM 06.5N TO 14N W OF 135W. ANOTHER SMALL 
AREA OF FRESH TRADEWINDS PREVAILS FROM 07N TO 10W BETWEEN 120W 
AND 135W. CIMMS SATELLITE DERIVED WIND FIELDS INDICATE ENHANCED 
LOW LEVEL CONVERGENCE OVER THIS AREA DUE TO THESE FRESH 
TRADEWINDS. THIS CONVERGENCE...AND UPPER LEVEL DIVERGENCE EAST 
OF A SHARP UPPER LEVEL TROUGH WITH AXIS CENTERED ROUGHLY ALONG 
140W IS STRONG ENOUGH TO MAINTAIN ACTIVE CONVECTION AS NOTED 
ABOVE. 

WITH THE AREA OF HIGH PRESSURE CONTINUING TO WEAKEN...TRADEWINDS 
WILL DIMINISH FURTHER BELOW 20 KT OVERNIGHT. THE ASSOCIATED 
HIGH PRESSURE RIDGE WILL SHIFT EASTWARD ENABLING A SURFACE COLD 
FRONT TO ENTER THE FAR NW PART OF THE AREA SUN. SW WINDS WILL 
FRESHEN OVER THE FAR NW PART OF THE AREA AHEAD OF THE COLD 
FRONT. THE COLD FRONT WILL RAPIDLY WEAKEN AND DISSIPATE BY 
MONDAY. HOWEVER...THE FRONT WILL USHER IN A LARGE LONG PERIOD NW 
SWELL EVENT...WITH COMBINED SEAS AS HIGH AS 20 FT PEAKING MON 
MORNING ACROSS THE FAR NW CORNER OF THE AREA. 

GULF OF PAPAGAYO...
FRESH TO STRONG TRADEWINDS OVER THE WESTERN CARIBBEAN CONTINUE 
TO FUNNEL THROUGH THE NICARAGUA MOUNTAINS INTO THE GULF OF 
PAPAGAYO. WINDS WILL PEAK DURING THE LATE NIGHT AND EARLY 
MORNING HOURS WITH THE ADDED COMPONENT OF NOCTURNALLY DRIVEN 
KATABATIC WINDS. 

GULF OF TEHUANTEPEC...
A WEAK TROUGH OVER THE YUCATAN PENINSULA JUST E OF THE BAY OF 
CAMPECHE COMBINED WITH HIGH PRESSURE OVER EASTERN MEXICO IS 
CREATING LOCALIZED NORTHERLY WINDS WHICH ARE FUNNELING THROUGH 
THE CHIVELA PASS RESULTING IN FRESH WINDS OVER THE GULF OF 
TEHUANTEPEC. WINDS FUNNELING THROUGH THE CHIVELA PASS WILL 
INCREASE SUN AHEAD OF A STRONG COLD FRONT SHIFTING ACROSS THE 
GULF OF MEXICO. WINDS ARE EXPECTED TO REACH GALE FORCE SUN 
EVENING AND PEAK AROUND 45 KT MON...WITH MAXIMUM SEAS BUILDING 
TO NEAR 18 FT MON AFTERNOON.
     
GULF OF PANAMA...
FRESH TO STRONG NE WINDS OVER THE SW CARIBBEAN WILL FUNNEL INTO 
ACROSS PANAMA. THIS WILL MAINTAIN FRESH 20 KT WINDS OVER THE 
GULF OF PANAMA THROUGH AT LEAST MONDAY MORNING.

$$
SS