000
AXPZ20 KNHC 210312
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE DEC 20 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0300 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...MONSOON 
TROUGH FROM 09N84W TO 07.5N90W TO 08N100W. ITCZ FROM 08N100W TO 
10N100W TO 09N130W. SCATTERED MODERATE TO STRONG CONVECTION WAS 
NOTED WITHIN 120 NM N AND 90 NM S OF AXIS BETWEEN 110W AND 120W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS NOTED WITHIN 
90 NM N OF AXIS BETWEEN 125W AND 130W. 

...DISCUSSION...
HIGH PRESSURE IS CENTERED N OF THE AREA WITH RIDGE EXTENDING TO 
21N112W. THE PRESSURE GRADIENT BETWEEN THE RIDGE OF HIGH PRES 
AND LOWER PRESSURE IN THE VICINITY OF THE ITCZ IS MAINTAINING 
FRESH TRADEWIND FLOW OVER OF THE AREA FROM 11N TO 22N W OF 130W 
AND FROM 09N TO 15N BETWEEN 110W AND 130W. FRESH SOUTHERLY FLOW 
PREVAILS S OF THE ITCZ AXIS FROM 02N TO 07N BETWEEN 110W AND 
117W. THE FRESH WINDS ON EITHER SIDE OF THE ITCZ OVER THIS AREA 
ARE PRODUCING ENOUGH CONVERGENCE TO MAINTAIN ACTIVE CONVECTION 
ALONG THE ITCZ AS NOTED ABOVE. THE AREA OF HIGH PRESSURE WILL 
PREVAIL N OF THE AREA...AND HELP MAINTAIN A PRESSURE GRADIENT TO 
SUPPORT THE FRESH TRADEWIND FLOW THROUGH THE FORECAST PERIOD 
WHICH RUNS THROUGH THU NIGHT.

FRESH WINDS OVER THE W CARIBBEAN ARE FUNNELING INTO THE GULF OF 
PAPAGAYO FROM 10N TO 12N E OF 89W. THE FRESH TRADEWINDS WILL 
CONTINUE OVER THE WESTERN CARIBBEAN WHICH WILL MAINTAIN THE 
FRESH WINDS OVER THE GULF OF PAPAGAYO THROUGH THE FORECAST 
PERIOD. THE WINDS OVER THE GULF OF PAPAGAYO WILL REACH A MAXIMUM 
DURING THE EARLY MORNING HOURS WITH THE ADDED CONTRIBUTION OF 
DRAINAGE FLOW. 

NW SWELL WILL PREVAIL OVER MUCH OF THE AREA W OF 110W THROUGH 
THE FORECAST PERIOD. THIS SWELL WILL MIX WITH SW SWELL S OF 
10N...AND NE SWELL IN THE REGION OF STRONGEST TRADES. 

$$
AL