000
AXPZ20 KNHC 222159
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC WED JUL 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 
2145 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE N OF 04N ALONG 83W HAS MOVED W AT 28 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 A CONVECTIVE 
BURST AT 06N ALONG THE WAVE AXIS THIS MORNING BUT CONVECTION IS 
CURRENTLY WEAKENING. THE DEBRIS MOISTURE COVERS THE DISCUSSION 
AREA N OF 02N E OF 85W INCLUDING CENTRAL AMERICA.      

A TROPICAL WAVE N OF 04N ALONG 95W HAS MOVED W AT ABOUT 20 KT 
OVER THE PAST 48 HOURS. CONVECTION IS FLARING WITHIN 120 NM OF 
THE WAVE FROM 04N TO 06N AND WITHIN 30 NM OF THE WAVE AXIS FROM 
06N TO 14N. THE WAVE IS WITHIN AN AREA OF WEAK UPPER LEVEL 
DIFFLUENCE BUT IS EXPECTED TO MOVE W INTO A LESS FAVORABLE UPPER 
SUPPORT THU AND FRI. 

A TROPICAL WAVE IS ANALYZED FROM 05N TO 14N BETWEEN 124W AND 
126W AND HAS BEEN MOVING W AT 15 KT. THIS WAVE IS MOVING INTO AN 
AREA OF SOUTHWESTERLY UPPER SHEAR AND CONVECTION IS NOW 
STRETCHING NE TO SW FROM 10N TO 14N. 
 
...ITCZ...
THE AXIS IS ALONG 10N83W TO 07N105W TO 11N125W TO 09N140W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED OVER THE 
ENTIRE AREA N OF 05N E OF 101W AND ALSO FROM 06N TO 14N BETWEEN 
117W AND 140W.   

...DISCUSSION...
THE UPPER LEVEL PATTERN IS SOMEWHAT COMPLEX OVER THE AREA W OF 
110W. A SMALL UPPER LEVEL ANTICYCLONE IS JUST W OF THE AREA AT 
15N145W WITH A NARROW RIDGE EXTENDING E INTO THE DISCUSSION AREA 
ALONG 15N140W TO 15N135W. AN UPPER LEVEL TROPICAL ANTICYCLONE IS 
CENTERED NEAR 13N119W. THE ASSOCIATED UPPER DIFFLUENCE HAS BEEN 
ENHANCING ITCZ CONVECTION W OF 117W. AN UPPER ANTICYCLONE 
CENTERED OVER NORTHERN OLD MEXICO AT 30N110W WITH ITS 
ANTICYCLONIC ENVELOPE EXTENDING S OVER THE AREA N OF 25N BETWEEN 
105W AND 115W. 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 09N96W. CONVECTION ALONG THE E PACIFIC ITCZ HAS 
BEEN ENHANCED E OF 100W 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 32N146W. 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 PINTS 23N144W TO 27N130W TO BEYOND 35N125W. A BAND OF 
DRY UPPER AIR IS NOTED WITHIN 120 NM EITHER SIDE OF POINTS 
15N140W TO 17N130W TO 25N118W. ANOTHER UPPER TROUGH EXTENDS S 
ALONG THE E COAST OF THE UNITED STATES TURNS SW DISSECTING THE 
GULF OF MEXICO INTO A SMALL UPPER CYCLONE AT 18N110W AND ANOTHER 
SMALLER CYCLONE AT 09N106W WITH THE UPPER TROUGH 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