000
AXPZ20 KNHC 222133
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI MAY 22 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.

...TROPICAL WAVES...
TROPICAL WAVE EXTEND S FROM W PANAMA ALONG 82W TO 02N.  MOST 
CONVECTION REMAINS OVER WATER FROM 02N-07N BETWEEN 78W-84W.  
WAVE UNDER AREA OF DIFFLUENT FLOW ALOFT LIKELY TO DEVELOP MORE 
DEEP CONVECTION NEXT 18-24 HRS...BUT SHOULD ENCOUNTER ADVERSE 
UPPER CONDITIONS AFTER THAT.  NO ORGANIZATION NOTED AT THIS TIME.

...ITCZ...
AXIS ALONG 07N78W TO 10NW TO 06N126W TO 06N137W TO 06N140W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 240 NM S OF 
AXIS E OF 98W AND WITHIN 75 NM OF AXIS FROM 129W-132W.

.DISCUSSION...
UPPER LEVEL RIDGE SPREADS ACROSS E PAC ALONG 10N-12N E OF 130W 
SUPPORTED BY SEVERAL ANTICYCLONES.  RIDGE ADVECTING ABUNDANT 
TROPICAL CONVECTION DEBRIS EASTWARD JUST ALONG ITCZ MAKING 
MOISTURE AVAILABLE TO ENHANCE MORE CONVECTION WHERE LOW LEVEL 
UPLIFTING IS FOUND.  THERE ARE TWO MAIN SOURCES OF UPLIFT...ONE 
IS LOW PRES CENTER 1008 MB AT 14N111W WITH SCATTERED MODERATE TO 
STRONG CONVECTION AND ANOTHER IS WITH TROPICAL WAVE AS DESCRIBED 
IN ITS SECTION ABOVE.  SOME MOISTURE SEEPS INTO WESTERN 
CARIBBEAN FEEDING LARGE BUT DECREASING AREA OF DEEP CONVECTION S 
OF HISPANIOLA.

MOST OF E PAC UPPER LEVEL WINDS REMAIN QUASI-ZONAL N OF 19N 
WHERE 85 KT JET CORE KEEPS A DRY AIR MASS UMBRELLA OVER REGION 
EXCEPT NEW SWATH OF MOISTURE ENTERING W SIDE OF BASIN AHEAD OF 
UPPER LEVEL TROUGH STILL W OF 140W.

.AT THE SURFACE...HIGH PRES CENTER 1032 MB WELL N OF REGION HAS 
RIDGE EXTEND SE TO 20N110W.  SYSTEM COMBINES WITH 1012 LOW PRES 
CENTER OVER CALIFORNIA TO PRODUCE N GALE FORCE WINDS ALONG COAST 
OF CALIFORNIA.  SWELL TRAINS BUILT BY GALE EVENTUALLY FIND THEIR 
WAY INTO E PAC N OF 27N FROM 120W-135W.

WEAK LOW PRES AT 12N122W ENHANCES FRESH NE TRADES WITH 8 FT SEAS 
FROM 11N-19N BETWEEN 125W-135W.  LOW PRES WEAKENS WITHIN 24 HRS 
AND TRADES DIMINISH BELOW 20 KT.  SECOND LOW PRES CENTER AT 
14N111W SITS UNDER ONE OF ANTICYCLONES WITH GOOD DIFFLUENT FLOW 
ALOFT ENHANCING DEEP CONVECTION FROM 09N-14N BETWEEN 110W-117W.
MODEL GUIDANCE STRENGTHENS THIS SYSTEM AS IT MOVES AWAY FROM 
ITCZ INFLUENCE WITH FRESH WINDS RESTRICTED MAINLY TO SE 
SEMICIRCLE DURING NEXT 48 HRS. 

$$
WALLY BARNES