000
AXPZ20 KNHC 261559
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE MAY 26 2009

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1515 UTC.

...TROPICAL WAVES...

THE TROPICAL WAVE BETWEEN 105W AND 115W IS VERY DIFFICULT TO 
LOCATE AND HAS BEEN DROPPED FROM THE SURFACE ANALYSIS. 

...ITCZ...

THE ITCZ AXIS EXTENDS ALONG 09N78W TO 12N98W TO 05N122W TO 
09N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED 
WITHIN 150 NM EITHER SIDE OF A LINE FROM 07N78W TO 06N93W TO 
07N108W TO 12N114W AND WITHIN 120 NM OF 14N125W...AND ALSO 
WITHIN 30 NM OF A LINE FROM 13N130W TO 06N138W. 

.DISCUSSION...

ALOFT...AN UPPER LEVEL SHORTWAVE TROUGH EXTENDS SW ALONG 32N108W 
TO 24N125W AND IS ACCOMPANIED BY DRY AIR WITHIN 150 NM EITHER 
SIDE OF ITS AXIS. A SECOND UPPER TROUGH IS LOSING IDENTITY ALONG 
24N107W TO 17N119W THEN CONTINUING S ALONG 124W INTO A SMALL 
UPPER CYCLONE AT02S125W. AN UPPER ANTICYCLONE IS AT 08N134W WITH 
A SHORTWAVE RIDGE EXTENDING N ALONG 20N137W TO AN AMPLIFYING 
CREST NEAR 36N137W. UPPER MOISTURE IS TRAPPED UNDER THE 
RIDGE...ROUGHLY N OF 17N BETWEEN 130W AND 142W. 

A TROPICAL MID TO UPPER LEVEL ANTICYCLONE IS ESTIMATED NEAR 
09N97W WITH A RIDGE W TO A SHARP CREST AT 11N116W. UPPER 
DIFFLUENCE HAS ENHANCED CONVECTION ALONG THE ITCZ UNDER THIS 
RIDGE WITH SOME OF THE MOISTURE SPREADING NE TO ALONG 20N 
BETWEEN 118W AND 92W WHERE IT EVAPORATES. THE SOUTH AMERICAN 
UPPER RIDGE IS CRESTING OVER PANAMA TODAY. E PACIFIC ITCZ 
CONVECTION IS ENHANCED BETWEEN 93W AND 73W WITH THE DEBRIS 
MOISTURE SPREADING NE OVER THE SW CARIBBEAN.
 
AT THE LOW LEVELS...A RIDGE EXTENDS SE ALONG 32N134W TO 16N105W. 
NE TRADES S OF THE RIDGE...FROM 12N TO 20N W OF 125W...ARE IN 
THE 15 TO 20 KT RANGE WITH SEAS TO 8 FT...BUT EXPECTED TO 
DIMINISH BELOW 20 KT TONIGHT. THE GRADIENT HAS TIGHTENED NE OF 
THE RIDGE ALONG THE BAJA PENINSULA SUPPORTING NW WINDS TO 20 KT. 
THIS GRADIENT SHOULD WEAKEN WED NIGHT LEAVING JUST A SMALL AREA 
OF NW WINDS TO 20 KT ALONG THE MEXICAN COAST FROM 16N TO 19N ON 
THU. 

$$
NELSON