000
AXPZ20 KNHC 132202
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE DEC 13 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 FROM 09N84W TO 05N92W TO 06N96W THEN ITCZ TO 
08N113W AND FROM 10N125W TO 09N140W.  SCATTERED MODERATE 
CONVECTION WITHIN 90 NM S OF AXIS FROM 109W TO 113W.

...DISCUSSION...
DEEP LAYER LONGWAVE TROUGH CUTS THROUGH MID SECTION OF BASIN 
ALONG 115W TO UPPER LEVEL CYCLONE AT 04N116W.  VERY DRY AIR MASS 
S OF 20N FROM 90W TO 130W EXCEPT SMALL BATCH YIELDING SCATTERED 
MODERATE CONVECTION ASSOCIATED WITH WEAK SURFACE TROUGH ALONG 
114W FROM 05N TO 14N.  WEAK SHORTWAVE TROUGH SLIDING ON W SIDE 
OF DEEP LAYER TROUGH PACKS ENOUGH ENERGY TO KICK WINDS UP JUST N 
OF 30N E OF 125W. ILL-DEFINED UPPER LEVEL ANTICYCLONE AT 08N130W 
EXTEND RIDGE N TO 32N136W.  MOISTURE FLOW ALONG RIDGE CREST N OF 
16N BUT EVAPORATES AS IT APPROACHES DEEP TROUGH AXIS.  SECOND 
RIDGE OVER SOUTH AMERICA ADVECTS LOW LEVEL MOISTURE INTO MONSOON 
TROUGH AXIS PROMPTING MINOR ISOLATED MODERATE CONVECTION WITHIN 
120 NM N OF AXIS.  

ELSEWHERE AT THE LOW LEVELS...
SURFACE LOW PRES 1013 MB AT 33N118W WITH WEAK TROUGH TO ITS NW 
PROMPTING FRESH NW BREEZE WHICH ENCROACHES INTO BASIN WITH SEAS 
BUILDING TO 12-14 FT N OF 27N.  LOW PRES MOVES E AND BRING 
SIMILAR WINDS INTO GULF OF CALIFORNIA BY LATE WED AND THU.  

STRONG N BREEZE CONTINUE ACROSS GULF OF TEHUANTEPEC BUT EXPECTED 
TO DIMINISH BELOW 20 KT BY LATE THU...ALTHOUGH SEAS LINGER AT 
8-9 FT BEYOND FORECAST PERIOD.  

$$
WALLY BARNES