000
AXPZ20 KNHC 182210
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SUN DEC 18 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 08N83W TO 06N98W THEN ITCZ TO 06N110W 
TO 10N121W TO 07N134W TO BEYOND 07N140W.  ISOLATED MODERATE 
CONVECTION WITHIN 90 NM OF AXIS FROM 114W TO 131W. 

...DISCUSSION...

DEEP LAYERED UPPER CYCLONE OVER FAR SOUTHERN ARIZONA DRIFTING E 
SHOULD EXIT AREA TONIGHT TAKING ITS ATTENDANT SURFACE LOW PRES 
1015 MB WITH IT.  SECOND AND DEEPER CYCLONE MOVES INTO SAME LATE 
MON WITH SIMILAR STRUCTURAL CONFIGURATION.  UPPER LEVEL TROUGH 
AXIS FROM CYCLONE MAINTAIN DRY AIR MASS N OF 22N FROM 110W TO 
130W WHILE ABUNDANT MOISTURE SURROUNDS DEEP CYCLONE WITHIN 240 
NM OF CENTER.  CONVECTION ASSOCIATED WITH CYCLONE CONTINUE TO 
IMPACT FORECAST AREA JUST N OF 30N THROUGH FORECAST PERIOD.  
SECOND CYCLONE WHILE MORE INTENSE IS EXPECTED TO REMAIN ON A 
SLIGHTLY MORE NORTHERLY TRACK THAN THE FIRST SO ITS FRONTAL 
BOUNDARY WINDS MIGHT NOT REACH S OF 30N...BUT ITS LONG PERIOD  
NW SWELL COULD REACH AS FAR S AS 20N.    

HIGH PRES CENTER 1027 MB ALLOWS FRESH TRADES TO EXPAND EASTWARD 
TO 110W MON AS RIDGE EXTENDS FURTHER E.  FRESH NW BREEZE FROM 
18N TO 22N E OF 108W EXPECTED TO DIMINISH AS RIDGE SLIDE E. 

GAP WINDS...
GULF OF TEHUANTEPEC...PRESENT GALE EVENT EXPECTED TO DIMINISH 
LATE TONIGHT AS HIGH PRES OVER SE CONUS SHIFTS EASTWARD REDUCING 
PRES GRADIENT BY EARLY MON.   

GULF OF PAPAGAYO...SAME PRES GRADIENT FORCING GALE WINDS IN GULF 
OF TEHUANTEPEC ALSO PUSHING FRESH TO STRONG WINDS ACROSS 
NICARAGUA INTO GULF OF PAPAGAYO WITH SPEEDS REACHING NEAR GALE 
FORCE EARLIER TODAY.  WINDS BEGIN TO DIMINISH TONIGHT AS HIGH 
PRES SHIFTS EASTWARD...BUT REMAIN FRESH THROUGH AT LEAST EARLY 
TUE...BEFORE DIMINISHING BELOW 20 KT LATE TUE.

$$
WALLY BARNES