000
AXPZ20 KNHC 182141
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE AUG 18 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 
2100 UTC.

...TROPICAL WAVES...
TROPICAL WAVE N OF 08N ALONG 100W MOVE W AT 15 KT APPROACHES 
SLIGHTLY LESS ADVERSE UPPER CONDITIONS WITH MODERATE DIFFLUENT 
FLOW JUST N OF 13N WHICH IS EXPECTED TO ENHANCE ITS CONVECTION 
WITHIN NEXT 18-24 HRS.  ALTHOUGH SOME CYCLONIC ROTATION NOTED IN 
SYSTEM...ENVIRONMENT TURNS MORE ADVERSE W OF 105W AND MODEL 
GUIDANCE DOES NOT SEE SIGNIFICANT INTENSIFICATION FOR SYSTEM. 
 
TROPICAL WAVE FROM 08N TO 16N ALONG 113W MOVE W AT 15 KT WITH  
ISOLATED MODERATE CONVECTION W OF AXIS NEAR ITCZ INTERSECTION.  
ADVERSE NE WIND SHEAR MAKES ANY SIGNIFICANT ORGANIZATION OF WAVE 
UNLIKELY.

TROPICAL WAVE FROM 07N TO 15N ALONG 126W MOVE W AT 15 KT WITH 
SCATTERED MODERATE ISOLATED STRONG CONVECTION FLARING WITHIN 240 
NM E OF AXIS.  THERE IS MODERATELY FAVORABLE CONDITION ALOFT S 
OF 12N NEAR ITCZ...BUT DRY STRONG SW SHEAR JUST NW OF AXIS WILL 
INHIBIT CONVECTION N OF 12N-13N.  MODEL GUIDANCE SOLUTION FAVOR 
DEVELOPMENT OF CYCLONIC CIRCULATION S OF 10N AS AXIS CROSSES 
140W.

...ITCZ...
AXIS ALONG 07N78W TO 11N98W TO 09N108W TO 12N115W TO 08N134W TO 
09N140W.  SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 
180 NM S OF AXIS E OF 108W.  ISOLATED MODERATE WITHIN 60 NM N OF 
AXIS W OF 137W.  REMAINDER CONVECTION ASSOCIATED WITH TROPICAL 
WAVES. 

...DISCUSSION...
UPPER LEVEL RIDGE CREST CROSS NW CORNER OF BASIN FROM 25N140W TO 
32N129W FEEDS STRONG DRY AIR MASS TO DOWNSTREAM CYCLONE AT 
19N128W.  DRY AIR MASS REACH AS FAR S AS 12N INHIBITING 
CONVECTION AHEAD OF TROPICAL WAVE ALONG 126W.  CYCLONE ALSO 
ADVECTS ABUNDANT MOISTURE FROM E SIDE OF WAVE AXIS NORTHWARD UP 
TO 20N.  

DOWNSTREAM ANTICYCLONE AT 22N116W BRINGING STRONG SHEAR TO N 
HALF OF WAVE AXIS ALONG 113W.  SHARP INVERTED TROUGH ALONG 104W 
INDUCING MODERATE UPPER LEVEL DIFFLUENCE TO N HALF OF TROPICAL 
WAVE ALONG 100W ENHANCING ITS CONVECTION N OF 14N E OF AXIS. 

ELSEWHERE AT THE SURFACE...
FRESH S BREEZE ACROSS EQUATOR BRING WARM MOIST WINDS S OF 08N   
E OF 115W WITH LONG PERIOD SWELLS NEAR 8 FT.

FRESH E BREEZE CROSSING COSTA RICA FROM WRN CARIBBEAN EXPECTED 
TO INCREASE GULF OF PAPAGAYO WINDS WITHIN 24-36 HRS WITH SEAS 
BELOW 8 FT.  

$$
WALLY BARNES