000
AXPZ20 KNHC 122151
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE MAY 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...
THE ITCZ AXIS IS ALONG POINTS 09N82W TO 08N87W TO 12N104W TO 
05N130W TO 04N140W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION IS NOTED FROM 05N TO 10N BETWEEN 80W AND 90W AND 
WITHIN 120 NM EITHER SIDE OF A LINE FROM 15N94W TO 10N115W AND 
ALSO WITHIN 120 NM EITHER SIDE OF A LINE FROM 07N123W TO 05N140W.

...DISCUSSION...
ALOFT...AN UPPER TROUGH IS ALONG THE W BOUNDARY OF THE 
DISCUSSION AREA FROM 32N140W TO 16N130W WITH ITS EASTWARD 
PROGRESS BLOCKED BY AN ANTICYCLONIC FLOW ASSOCIATED WITH UPPER 
ANTICYCLONE CENTERED NEAR 23N131W. UPPER MOISTURE IS NOTED OVER 
THE AREA FROM 23N TO 34N BETWEEN 138W AND 132W...OTHERWISE DRY 
UPPER AIR IS INDICATED WITHIN 120 NM OF THE TROUGH AXIS ALONG 
140W AND CONTINUES SE OVER THE ENTIRE DISCUSSION AREA FROM 09N 
TO 22N BETWEEN 145W AND 120W. A SECOND UPPER TROUGH HAS SWUNG SE 
OVER THE NORTHERN PORTION ALONG 32N117W TO 28N127W ACCOMPANIED 
BY DRY UPPER AIR WITHIN 120 NM OF ITS AXIS. 

A SECOND UPPER ANTICYCLONE IS NEAR 15N100W WITH A RIDGE 
EXTENDING N TO OVER W TEXAS. A THIRD UPPER ANTICYCLONE IS OVER 
VENEZUELA WITH A RIDGE EXTENDING W OVER THE TROPICAL E PACIFIC 
TO A SHARP CREST AT 09N86W. AN UPPER TROUGH EXTENDS SW ACROSS 
THE NW CARIBBEAN ALONG 20N80W TO 11N92W SEPARATING THE TWO 
ANTICYCLONES. UPPER DIFFLUENCE IS ENHANCING CONVECTION ALONG THE 
ITCZ BETWEEN 95W AND 116W WITH THE DEBRIS MOISTURE ADVECTED N 
OVER OLD MEXICO BETWEEN 98W AND 118W. CONVECTION ALONG THE ITCZ 
IS ALSO ENHANCED BETWEEN 91W AND 78W WITH SOME OF THE DEBRIS 
MOISTURE SPREADING NE ACROSS CENTRAL AMERICA AND THE SW 
CARIBBEAN TURNING E NEAR 15N77W TO BEYOND THE VIRGIN ISLANDS.
       
AT THE LOW LEVELS...A RIDGE EXTENDS SE ALONG 32N131W TO 17N106W. 
NORTHERLY WINDS TO 20 KT ARE NE OF THE RIDGE OVER THE AREA N OF 
23N E OF 130W TO THE BAJA COAST WITH LITTLE CHANGE EXPECTED FOR 
A COUPLE OF DAYS. A SMALL AREA OF NE TRADES TO 20 KT ARE 
OBSERVED S OF THE RIDGE FROM 09N TO 15N W OF 127W AND EXPECTED 
TO DIMINISH THU.      

GULF OF PAPAGAYO GAP...NE WINDS IN THE W CARIBBEAN ARE 
OCCASIONALLY SURGING THROUGH THE GULF OF PAPAGAYO AT 20 
KT...ESPECIALLY BEGINNING LATE AT NIGHT TO MID MORNING. THESE 
CONDITIONS SHOULD DIMINISH THU.

$$
NELSON