000
AXPZ20 KNHC 290310
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU DEC 29 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 AXIS 04N77W TO 09N85W TO 06N108W. ITCZ AXIS 
06N108W TO 06N120W TO 10N134W TO BEYOND 09N140W. SCATTERED 
MODERATE ISOLATED STRONG WITHIN 240 NM E OF TROUGH AXIS FROM 12N 
TO 15N. SCATTERED MODERATE WITHIN 60 NM OF THE ITCZ BETWEEN 130W 
AND 138W.

...DISCUSSION...

A MID TO UPPER LEVEL SHEAR AXIS EXTENDS WESTWARD ALONG THE U.S.
MEXICO BORDER FROM 32N105W TO 30N130W THEN TURNS SW INTO A SHARP 
UPPER LEVEL TROUGH WITH AN EMBEDDED CYCLONE CUTTING OFF NEAR 
17N145W. VERY STRONG MID TO UPPER LEVEL SUBSIDENCE WAS NOTED 
WITHIN 90-120 NM EITHER SIDE OF THE SHEAR AXIS AND SPILLING INTO 
THE BACKSIDE OF THE TROUGH AND WRAPPING AROUND THE S SEMICIRCLE 
OF THE UPPER CYCLONE. A MID TO UPPER LEVEL ANTICYCLONE CENTERED 
NEAR 14N107W WITH A RIDGE EXTENDING NW TO 25N133W. AN UPPER 
TROUGH/CYCLONE IS NOTED S OF THE EQUATOR RESULTING IN 
NORTHWESTERLY FLOW IN THE UPPER LEVELS SW OF A LINE FROM 10N140W 
TO 00N115W RESULTING IN A LARGE AREA OF UPPER LEVEL DIFFLUENCE 
FROM 10N TO 25N BETWEEN 120W AND 138W. THIS ENVIRONMENT WAS
PROVIDING ENOUGH LIFT ALONG A SURFACE TROUGH EXTENDING FROM 
10N135W TO 17N134W TO SUPPORT SCATTERED MODERATE CONVECTION 
WITHIN 240 NM E OF THE TROUGH AXIS FROM 12N TO 15N. A VAST AREA 
OF UPPER LEVEL MOISTURE/CONVECTIVE DEBRIS WAS INDICATED WITHIN 
AN AREA FROM 10N TO 26N BETWEEN 115W AND 138W. SOME OF THIS 
UPPER MOISTURE SPREADS E IN UPPER ZONAL FLOW ACROSS THE UPPER 
RIDGE OVER NORTHERN MEXICO...ROUGHLY FROM 20N TO 30N E OF 115W.

FURTHER E...A SHEARED UPPER TROUGH EXTENDS SW FROM THE STRAITS 
OF FLORIDA ACROSS THE EXTREME W CARIBBEAN SEA TO A SHEAR AXIS 
OVER THE E PACIFIC EXTENDING FROM GUATEMALA TO A COL NEAR 
10N98W. THE UPPER LEVELS APPEAR VERY DRY TO THE S OF 17N E OF 
106W...WITH THE DEBRIS MOISTURE FROM ISOLATED CONVECTION ALONG 
THE MONSOON TROUGH ALONG 90W QUICKLY EVAPORATING IN THIS DRY 
ENVIRONMENT. 

AT THE SURFACE...A 1030 MB HIGH PRES AREA CENTERED NEAR 
32N134W WILL DRIFT WSW THROUGH THU. A BROAD LOW LEVEL TROUGH 
EXTENDING FROM 10N135W TO 17N134W IS MOVING W AT ABOUT 10 KT. 
THE TIGHTER PRESSURE GRADIENT BETWEEN THIS TROUGH AND THE 
SURFACE HIGH TO THE NORTH IS MAINTAINING NE TO E 20 TO 25 KT 
TRADEWINDS OVER THE AREA BETWEEN 09N TO 20N W OF 120W. THE 
SURFACE TROUGH AND AREA OF ENHANCED TRADES WILL SHIFT W OF 140W 
THU NIGHT AND FRI. NW SWELL WILL CONTINUE TO PROPAGATE SE OVER 
THE WATERS W OF 110W...MIXING WITH NE TRADE SWELL...AND EVEN SE 
CROSS EQUATORIAL SWELL S OF 17N W OF 110W. 

GULF OF TEHUANTEPEC...
SURFACE OBSERVATIONS FROM AROUND THE GULF OF TEHUANTEPEC SUGGEST 
NORTHERLY WINDS ARE ESTIMATED TO HAVE DIMINISHED TO 20 TO 25 KT. 
THESE WINDS ARE EXPECTED TO CONTINUE TO DIMINISH TO 20 KT MOSTLY 
DUE TO LATE NIGHT DRAINAGE FLOW THROUGH EARLY FRI. A LARGE AREA 
OF NE SWELL TO 9 FT WILL PROPAGATE SW OVER THE WATERS S OF 13N 
BETWEEN 95W AND 110W THROUGH THU THEN SUBSIDE FROM THE N ON FRI.

GULF OF CALIFORNIA...THE PRESSURE GRADIENT BETWEEN PERSISTENT 
HIGH PRESSURE CENTER NW OF THE GULF OF CALIFORNIA...AND 
TROUGHING OVER MEXICO WILL MAINTAIN NW 15-20 KT WINDS OVER THE 
GULF OF CALIFORNIA THROUGH TONIGHT THEN DIMINISH BELOW 20 KT 
EARLY THU. 

GULF OF PAPAGAYO...FRESH TRADEWINDS OVER THE WESTERN CARIBBEAN 
WILL CONTINUE TO FUNNEL INTO THE GULF OF PAPAGAYO AT 20-25 KT 
THEN SLOWLY SUBSIDE TO AROUND 20 KT THU AND FRI WITH WINDS 
PEAKING DURING THE EARLY MORNING HOURS.

$$
COBB