000
AXPZ20 KNHC 212150
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC THU MAY 21 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 
2100 UTC.

...ITCZ...
AXIS ALONG 06N77W TO 13N116W TO 13N120W TO 07N130W TO 06N140W.  
SCATTERED MODERATE TO STRONG CONVECTION WITHIN 150 NM OF AXIS E 
OF 88W...WITHIN 180 NM OF 11N110W...AND WITHIN 75 NM OF 09N121W.

.DISCUSSION...
MID/UPPER E-W RIDGE WITH AXIS BETWEEN 10N-12N STRETCHES E OF 
128W MAINTAINING GOOD OUTFLOW OVER ITCZ AND ENHANCING CONVECTION 
CAUSED BY TWO SURFACE LOW PRES CENTERS...ONE AT 12N121W WITH 
1008 MB AND A SECOND ONE AT 11N110W...ALSO 1008 MB.  VERY DRY 
QUASI-ZONAL JET CORE OF 80 KT FLOW ALOFT N OF 20N W OF 105W NOT 
ALLOWING ANY MOISTURE INTO ITS BOUNDARIES.  ITCZ CONVECTION 
DEBRIS FOLLOW RIDGE NORTHERN PERIPHERY S OF 20N FLOWING E INTO 
NORTHWESTERN CARIBBEAN FEEDING AREA OF STRONG UPPER DIFFLUENCE 
...HENCE ABUNDANT DEEP CONVECTION IN THAT BASIN.

WESTERNMOST LOW PRES MENTIONED ABOVE UNDER INCREASINGLY 
UNFAVORABLE UPPER ENVIRON SHOULD WEAKEN AND DISSIPATE BY FRI. 
EASTERNMOST LOW PRES CENTER REMAINS CLOSE TO ANTICYCLONE ALOFT 
AT 10N106W AND IS EXPECTED TO PRODUCE FRESH TO STRONG BREEZE BY 
END OF FORECAST PERIOD. 

ELSEWHERE AT THE SURFACE...
HIGH PRES CENTER 1030 MB WELL N OF BASIN HAS RIDGE EXTEND SE TO 
15N09W PRODUCING FRESH TRADES WITH 8 FT SEAS W OD 122W.  SYSTEM 
COMBINES WITH LOW PRES CENTER 1011 MB OVER NORTHERN CALIFORNIA 
TO PRODUCE GALE FORCE WINDS ALONG COAST OF CALIFORNIA SPILLING 
INTO E PAC N OF 28N WITHIN 36 HRS.  

$$
WALLY BARNES