000
AXPZ20 KNHC 200950
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC MON JUL 20 2009

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...TROPICAL WAVES...
TROPICAL WAVE ALONG 112W FROM 04N TO 15N MOVING W 15 KT ENTERS 
SMALL REGION OF UPPER LEVEL DIFFLUENCE AND HAS SCATTERED 
MODERATE ISOLATED STRONG CONVECTION WITHIN 180 NM AHEAD OF 
AXIS.  MODEL GUIDANCE DEVELOP WEAK LOW PRES ALONG WAVE AXIS BUT 
LIMITS ITS GROWTH SINCE UNFAVORABLE AIR MASS LIES NOT TO FAR 
AHEAD.
 
TROPICAL WAVE ALONG 135W FROM 05N TO 13N MOVING W 15 KT.  
ISOLATED CONVECTION REMAINS MODERATE NEAR WAVE AXIS AS DRY AIR 
ENVIRONMENT AND NE SHEAR TAKES ITS TOLL ON SYSTEM.

...ITCZ...
AXIS ALONG 07N77W TO 09N134W TO 09N140W.  SCATTERED MODERATE TO 
STRONG CONVECTION E OF 80W.  ISOLATED MODERATE CONVECTION WITHIN 
180 NM N OF AXIS W OF 100W.

...DISCUSSION...
CYCLONIC CIRCULATION NW OF BASIN HAS TROUGH EXTEND THROUGH 
32N140W TO CUT OFF CYCLONIC VORTEX AT 19N126W.  AREA WEST OF 
VORTEX REMAINS VERY DRY UNDER UPPER LEVEL RIDGE WHICH COVERS 
AREA W OF 130W.  SWATH OF MID/UPPER LEVEL MOISTURE DEBRIS FROM  
ITCZ ADVECTS NE INTO WESTERN MEXICO AND SOUTHERN BAJA ON E SIDE 
OF CIRCULATION.  

MID/UPPER LEVEL RIDGE OVER CENTRAL CARIBBEAN COMBINES WITH 
SURFACE UPLIFT OF MOIST WARM TROPICAL AIR AND APPROACHING 
TROPICAL WAVE AXIS ALONG 74W TO ENHANCE SCATTERED MODERATE TO 
STRONG CONVECTION IN GULF OF PANAMA.   

FRESH NE TO E GAP WINDS IN GULF OF PAPAGAYO AND DOWNSTREAM 
CONTINUE THROUGH TODAY THEN DIMINISH THROUGH DAY TUE.  LONG 
DURATION OF THESE WINDS HAVE BUILT DOWNCURRENT SWELLS AS FAR AS
100W.  CROSS EQUATORIAL SWELLS ALSO ADD TO BUILDING SEAS S OF 
12N W OF 90W.

$$
WALLY BARNES