000
AXPZ20 KNHC 230339
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU JUL 23 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.

...TROPICAL WAVES...
A TROPICAL WAVE N OF 04N ALONG 84W HAS MOVED W AT 25 KT OVER THE 
PAST 24 HOURS. THE WAVE IS MOVING UNDER AN AREA OF UPPER LEVEL 
DIFFLUENCE ASSOCIATED WITH ANTICYCLONE CENTERED N OF THE AREA 
OVER THE W CARIBBEAN. THIS DIFFLUENCE SUPPORTED CONVECTION 
EARLIER BUT MOST OF THE CONVECTIVE HAS SINCE DISSIPATED.
   
A TROPICAL WAVE N OF 04N ALONG 97W HAS MOVED W AT ABOUT 20 KT 
OVER THE PAST 48 HOURS. CONVECTION IS FLARING WITHIN 120 NM W OF 
THE WAVE FROM 07N TO 14N. THE WAVE IS WITHIN AN AREA OF WEAK 
UPPER LEVEL DIFFLUENCE BUT IS EXPECTED TO MOVE INTO A LESS 
FAVORABLE UPPER SUPPORT ON THU AND FRI. 

A TROPICAL WAVE IS ANALYZED FROM 05N TO 14N BETWEEN 122W AND 
128W AND HAS BEEN MOVING W AT ABOUT 15 KT. THIS WAVE IS MOVING 
INTO AN AREA OF SOUTHWESTERLY UPPER SHEAR AND CONVECTION 
CONTINUES TO STRETCH FROM NE TO SW FROM 10N TO 14N. 
 
...ITCZ...
THE AXIS IS ALONG 09N78W TO 09N96W TO 12N125W TO 09N140W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED OVER THE 
ENTIRE AREA N OF 04N E OF 102W AND ALSO FROM 06N TO 13N W OF 
121W. 

...DISCUSSION...
AN UPPER LEVEL TROPICAL ANTICYCLONE IS CENTERED NEAR 13N118W. 
THE ASSOCIATED UPPER DIFFLUENCE HAS BEEN ENHANCING ITCZ 
CONVECTION W OF 116W. AN UPPER ANTICYCLONE IS CENTERED OVER 
NORTHERN OLD MEXICO AT 31N107W WITH ITS ANTICYCLONIC ENVELOPE 
EXTENDING S OVER THE AREA N OF 26N BETWEEN 100W AND 114W. 
ANOTHER UPPER ANTICYCLONE CENTERED OVER THE SW CARIBBEAN... 
PREVIOUSLY MENTIONED...HAS A RIDGE EXTENDING SW ACROSS CENTRAL 
AMERICA AND OVER THE DEEP TROPICAL PACIFIC TO A RIDGE CREST AT 
10N97W. CONVECTION ALONG THE E PACIFIC ITCZ HAS BEEN ENHANCED E 
OF 101W WITH SOME OF THE DEBRIS CIRRUS ADVECTED NE ACROSS 
CENTRAL AMERICA AND THE NW CARIBBEAN...AND SOME OF THE MOISTURE 
IS ADVECTED S TO ALONG 03N...BETWEEN 100W AND 78W... WHERE IT 
EVAPORATES.  

AN UPPER LEVEL SHORTWAVE TROUGH EXTENDS FROM VANCOUVER CANADA TO 
A DEEP LAYERED CYCLONE AT 32N144W. A BROAD BAND OF UPPER LEVEL 
MOISTURE....THAT ORIGINATES FROM ITCZ CONVECTION IN THE CENTRAL 
PACIFIC...IS SWINGING CYCLONICALLY THROUGH THE PATTERN WITHIN 
300 NM OF LINE FROM 24N140W TO BEYOND 32N127W. A BAND OF DRY 
UPPER AIR IS NOTED WITHIN 120 NM EITHER SIDE OF POINTS 16N140W 
TO 16N131W TO 26N118W. ANOTHER UPPER TROUGH EXTENDING S ALONG 
THE E COAST OF THE UNITED STATES TURNS SW DISSECTING THE GULF OF 
MEXICO INTO AN UPPER CYCLONE AT 14N104W WITH THE TROUGH 
CONTINUING S AND CROSSING THE EQUATOR AT 102W.  

GAP WINDS...NE TO E WINDS IN AND JUST DOWNSTREAM OF THE GULF OF 
PAPAGAYO WILL PULSE TO 20 KT OVER THE NEXT FEW DAYS.

LONG PERIOD SOUTHERLY SWELLS RESULTING IN MAX SEAS OF 8 TO 13 FT 
ARE CROSSING THE EQUATOR AND ARE FORECAST TO MOVE THROUGH THE 
TROPICAL E PACIFIC REACHING THE PACIFIC COAST OF CENTRAL AMERICA 
LATE THU AND AS FAR N AS THE CENTRAL BAJA PENINSULA LATE FRI.

$$
NELSON