000
AXPZ20 KNHC 090953
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SAT MAY 09 2009

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...ITCZ...
AXIS ALONG 08N83W TO 06N95W TO 07N111W TO 05N140W.  SCATTERED 
MODERATE ISOLATED STRONG CONVECTION WITHIN 120 NM S OF AXIS FROM 
86W TO 98W.  SCATTERED MODERATE CONVECTION WITHIN 90 NM OF AXIS  
W OF 134W.

...DISCUSSION...
LARGE CUTOFF CYCLONIC CIRCULATION CENTERED AT 21N118W KEEPS VERY 
DRY AIR MASS TO ITS N AND W WHILE ADVECTING LARGE AMOUNTS OF 
TROPICAL MOISTURE ON ITS SE QUADRANT ADVECTED BY 50 KT JET CORE. 
UPPER DIFFLUENT FLOW ENHANCES MINOR CONVECTION ALONG AXIS OF 
WEAK SURFACE TROUGH ALONG 109W.  MOISTURE HEADS NE INTO MEXICO 
MAKING IT AVAILABLE TO THERMAL LOW PRES TROUGH ALONG CENTRAL 
MEXICO AND CONTINUE INTO CENTRAL TEXAS WHERE HEALTHY COLD FRONT 
GENERATES STRONG CONVECTION.  

ANTICYCLONIC CIRCULATION AT 12N100W IS WESTERN EXTENSION OF 
RIDGE OVER CENTRAL AMERICA WHICH MAINTAINS DRY CONDITIONS E OF 
105W S OF ITCZ.  

SURFACE HIGH PRES 1034 MB WELL N OF AREA COMBINES WITH LOW PRES 
1002 MB OVER SOUTHERN CALIFORNIA TO FORCE GALE FORCE WINDS ALONG 
COAST OF CALIFORNIA JUST N OF E PAC BASIN...BUT NORTHERLY 20-25 
KT WINDS STILL ENCROACH S INTO FORECAST WATERS CYCLONIC TO REACH 
25N  AND GENERATING SWELL TRAINS THAT REACH TO 20N.  

WEAK NE TRADES DIMINISH FURTHER BELOW 20 KT WITHIN NEXT 24 HRS 
AS HIGH PRES IS FORCED E BY INCOMING COLD FRONT NOW ALONG 150W.  

$$
WALLY BARNES