000
AXPZ20 KNHC 122204
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC THU MAR 12 2009

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2145 UTC.

...ITCZ...
AXIS ALONG 08N83W TO 02N102W TO 05N140W. 
ISOLATED MODERATE WITHIN 30 NM OF AXIS E OF 91W. 

...DISCUSSION...
BROAD RIDGE MAINTAINS ANTICYCLONIC FLOW ALOFT W OF 110W BRINGING 
ABUNDANT MOISTURE RIDING A 140 KT JET CORE N OF 13N INTO BAJA 
CALIFORNIA AND MEXICO.  REST OF AREA W OF 110W REMAIN DRY UNDER 
RIDGE SUBSIDENCE.  CREST OF RIDGE FLATTENED BY QUICK MOVING 
SHORT WAVE NOW AT 32N114W.  WEAK UPPER LEVEL TROUGH FROM TEXAS 
ACROSS CENTRAL MEXICO INTO 14N110W EXTEND DRY AREA E TO CENTRAL 
AMERICA AND BEYOND EXCEPT SMALL ARA OF CLOUDINESS ALONG ITCZ E 
OF 91W.
  
MAIN FEATURE TO DISCUSS IS DEEP LAYER LARGE AMPLITUDE TROUGH 
APPROACHING THE WRN BOUNDARY OF BASIN.  EXPECT CUT OFF CYCLONIC 
VORTEX TO SPIN OFF TROUGH WITH SURFACE LOW PRES DEVELOPING JUST 
W OF 140W AND ASSOCIATED COLD FRONT JUST ALONG 140W.  LOW PRES 
EXPECTED TO PRODUCE STORM FORCE WINDS JUST N AND W OF FORECAST 
AREA WITH BUILDING SEAS ENCROACHING INTO E PAC LATE IN FORECAST 
PERIOD AND BEYOND.  

ELSEWHERE AT THE SURFACE...
HIGH PRES CENTER WELL N OF AREA HAS RIDGE EXTEND TO 12N102W.
WHILE TRADE WINDS DIMINISH WITH WEAKENING RIDGE...WATERS NEAR NW 
CORNER WILL FEEL IMPACT OF DEVELOPING LOW PRES NEARBY.  
ASSOCIATED NW SWELLS PROPAGATE SE THROUGH WATERS N OF 20N W OF 
110W.  ADDITIONALLY...LONG PERIOD SW SWELLS MOVING NE OVER SRN 
WATERS EVENTUALLY DOMINATE SE PART OF E PAC ALONG CENTRAL 
AMERICA COAST.

NE WINDS CONTINUE TO BRIDGE ACROSS GULF OF PAPAGAYO EXPECTED TO 
DIMINISH SAT.  SIMILARLY...GULF OF PANAMA N WINDS SHOULD BECOME 
BELOW 20 KT SAT.  

$$
WALLY BARNES