000
AXPZ20 KNHC 130343
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED MAY 13 2009

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0315 UTC.

...ITCZ...

THE ITCZ AXIS IS ALONG POINTS 09N82W TO 07N92W TO 09N112W TO 
03N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED 
WITHIN 120 NM EITHER SIDE OF LINE 07N77W TO 07N90W TO 
09N97W...AND WITHIN 150 NM OF 11N112W AND 5N137W.

...DISCUSSION...

ALOFT...AN UPPER TROUGH IS ALONG THE W BOUNDARY OF THE 
DISCUSSION AREA FROM 32N140W TO 24N138W INTO A DEVELOPING UPPER 
CYCLONE AT 24N136W WITH THE TROUGH CONTINUING E TO ANOTHER 
CYCLONE AT 19N127W. THIS SYSTEM IS NEARLY STATIONARY WITH ITS 
EASTWARD PROGRESS BLOCKED BY AN ANTICYCLONIC FLOW ASSOCIATED 
WITH UPPER ANTICYCLONE CENTERED NEAR 24N127W. UPPER MOISTURE IS 
NOTED OVER THE AREA FROM 24N TO 33N BETWEEN 139W AND 130W... 
OTHERWISE DRY UPPER AIR IS INDICATED WITHIN 120 NM W OF THE 
TROUGH AXIS ALONG 140W AND OVER THE ENTIRE DISCUSSION AREA FROM 
10N TO 22N BETWEEN 142W AND 120W. A SECOND UPPER TROUGH HAS 
SWUNG SE OVER THE NORTHERN PORTION ALONG 32N115W TO 28N125W AND 
ABOUT TO MERGE WITH YET ANOTHER UPPER TROUGH FROM 32N103W TO 
27N122W. DRY UPPER AIR IS NOTED FROM 26N TO 32N BETWEEN 108W AND 
122W. 

A SECOND UPPER ANTICYCLONE IS NEAR 14N98W WITH A RIDGE EXTENDING 
N TO OVER CENTRAL TEXAS. A THIRD UPPER ANTICYCLONE IS OVER 
VENEZUELA WITH A RIDGE EXTENDING W OVER THE TROPICAL E PACIFIC 
TO A SHARP CREST AT 09N88W. AN UPPER TROUGH EXTENDS SW ACROSS 
THE NW CARIBBEAN ALONG 20N80W TO 16N88W TO 09N93W SEPARATING THE 
TWO ANTICYCLONES. UPPER DIFFLUENCE IS ENHANCING CONVECTION ALONG 
THE ITCZ BETWEEN 93W AND 115W WITH THE DEBRIS MOISTURE ADVECTED 
N OVER OLD MEXICO BETWEEN 97W AND 112W. CONVECTION ALONG THE 
ITCZ IS ALSO ENHANCED BETWEEN 91W AND 80W WITH SOME OF THE 
DEBRIS MOISTURE SPREADING NE ACROSS CENTRAL AMERICA AND THE SW 
CARIBBEAN TURNING E AND CONTINUING E ACROSS THE NE CARIBBEAN 
ISLANDS.
       
AT THE LOW LEVELS...A RIDGE EXTENDS SE ALONG 32N133W 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 
ABOUT 24 HOURS THEN THE N WINDS WILL INCREASE TO 20 TO 25 KT 
WITH SEAS BUILDING TO 13 FT. 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