000
AXPZ20 KNHC 250939
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN DEC 25 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...MONSOON 
TROUGH AXIS FROM 09N84W TO 06N93W TO 08N105W. ITCZ AXIS FROM 
08N105W TO 10N131W TO BEYOND 08N140W. SCATTERED MODERATE 
CONVECTION WITHIN 90 NM N OF AXIS FROM 105W TO 120W.

...DISCUSSION...
GULF OF CALIFORNIA...UPPER LEVEL TROUGH HAS HELPED INDUCE A 
SURFACE TROUGH OVER ARIZONA. THIS HAS HELPED WEAKEN THE PRESSURE 
GRADIENT AND RESULTING WINDS FLOWING INTO THE GULF OF 
CALIFORNIA. WINDS ARE CURRENTLY BELOW GALE FORCE...AND WILL 
CONTINUE TO FURTHER DIMINISH WITH ONLY A SMALL AREA OF FRESH 20 
KT WINDS REMAINING BY LATE MONDAY. 

GULF OF TEHUANTEPEC...RECENT ASCAT AND WINDSAT PASSES INDICATE 
20 TO 25 KT GAP WINDS OVER THE GULF OF TEHUANTEPEC. ANOTHER 
SURGE OF COOLER...DRIER AND DENSER AIR WILL REACH THE BAY OF 
CAMPECHE LATER TODAY...AND WINDS ARE EXPECTED TO INCREASE TO 
GALE FORCE AGAIN BY THIS EVENING. WINDS ARE THEN EXPECTED TO 
DIMINISH BELOW GALE FORCE LATE MON AFTERNOON AS THE AIRMASS TO 
THE N MODIFIES. LOOKING AHEAD...OVERNIGHT DRAINAGE EFFECTS WILL 
ALLOW WINDS TO SURGE TO 30 KT BY EARLY TUE MORNING...BUT WINDS 
WILL CONTINUE TO GRADUALLY DIMINISH OTHERWISE THROUGH MIDWEEK. 
THE GALES COMING THROUGH TEHUANTEPEC WILL GENERATE A PLUME OF 
FRESH NE SWELL WITH HEIGHTS GREATER THAN 8 FT REACHING AS FAR W 
AS 105W THROUGH 48 HOURS.

GULF OF PAPAGAYO...FRESH TRADEWINDS OVER THE WESTERN CARIBBEAN 
WILL FUNNEL INTO THE GULF OF PAPAGAYO. WINDS WILL PEAK DURING 
THE EARLY MORNING HOURS WITH THE ADDITION OF NOCTURNALLY DRIVEN 
KATABATIC WINDS.

W OF 110W...A COLD FRONT EXTENDING FROM N OF 45N130W TO 30N143W 
WILL APPROACH THE NW CORNER OF THE DISCUSSION AREA TODAY BUT 
BECOME DIFFUSE. 1033 MB SURFACE HIGH PRES BEHIND THE FRONT WILL 
MERGE WITH 1032 MB SURFACE HIGH PRES AHEAD OF THE FRONT NEAR 
33N129 THROUGH MON. FURTHER SOUTH...A SURFACE TROUGH EXTENDS 
FROM 14N132W TO 07N133W. ASCAT DATA FROM 0650 UTC SHOWS 20 KT 
TRADE WINDS BETWEEN THE MERGING HIGH PRES N OF THE AREA AND THE 
TROUGH. THESE WINDS WILL INCREASE TO 30 KT NEAR THE TROUGH 
THROUGH 24 HOURS. THE SURFACE TROUGH WILL INTERACT WITH AN UPPER 
TROUGH TO THE NW AND AMPLIFY AS IT GRADUALLY SHIFTS W OF 140W 
THROUGH 72 HOURS. THIS WILL TIGHTEN THE PRES GRADIENT AND ALLOW 
TRADE WINDS TO INCREASE TO 20 TO 25 KT W OF 130W...REACHING 30 
KT NEAR THE SURFACE TROUGH AXIS BY 24 HOURS. NE FLOW TO 20 KT 
CONTINUE TO BREACH GAPS OVER THE BAJA CALIFORNIA PENINSULA AN 
INTO ADJACENT PACIFIC WATERS. THIS LOCALIZED GAP FLOW WILL 
DIMINISH THROUGH MON AS WINDS OVER THE THE GULF OF CALIFORNIA 
DIMINISH.

MEANWHILE...NW SWELL WITH PERIODS TO 15 SECONDS WILL INTERACT 
WITH THE FRESH TO STRONG NE TRADE WIND FLOW AND ALLOW SEAS TO 
BUILD TO AS HIGH AS 16 FT NEAR THE SURFACE TROUGH AXIS. THE NW 
SWELL WILL BRING SEAS TO 8 FT OVER MUCH OF THE AREA W OF 115W BY 
LATE TUE. 

$$
CHRISTENSEN