000
AXPZ20 KNHC 281603
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU MAY 28 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...
TROPICAL WAVE ALONG 88W FROM 04N-12N MOVING W AT 15 KT. 
ASSOCIATED SCATTERED DEEP CONVECTION N OF ITCZ HAS BEEN UNDER 
INCREASING NORTHERLY SHEAR WHICH HAS DAMPEN ITS DEVELOPMENT. 
S OF ITCZ...LESSER SHEAR AND APPROACHING MORE FAVORABLE UPPER 
LEVEL CONDITIONS POINT TO AN INCREASE IN DEEP CONVECTION.  
ALTHOUGH NO CYCLONIC ORGANIZATION IS EXPECTED NEXT 48 HRS... 
SYSTEM MERITS MONITORING. 

...ITCZ...
ITCZ ALONG 07N78W TO 07N82W TO 11N97W TO 09N111W TO 08N120W TO 
03N136W TO 03N140W.  SCATTERED MODERATE TO STRONG CONVECTION 
WITHIN 150 NM N AND 210 NM S OF AXIS E OF 90W.  SCATTERED 
MODERATE TO STRONG CONVECTION WITHIN 150 NM S OF AXIS FROM 
99W-108W.  SCATTERED MODERATE TO STRONG CONVECTION WITHIN 180 NM 
S OF AXIS FROM 112W-122W.

...DISCUSSION...
UPPER LEVEL CYCLONIC VORTEX AT 32N125W HAS WEAK TROUGH EXTEND SE 
TO 13N118W WITH DOWNSTREAM MID TO UPPER LEVEL BROAD RIDGE 
CENTERED AROUND ANTICYCLONE AT 10N92W.  SECOND ANTICYCLONE AT 
07N109W AND A THIRD ONE AT 06N139W PREVIEWS INCOMING UPSTREAM 
RIDGE APPROACHING 140W.  PLENTY OF TROPICAL MOISTURE AVAILABLE 
FOR ITCZ CONVECTION WITH E-W ELONGATED RIDGE ASSISTING DEBRIS 
OUTFLOW ALONG ITS NORTHERN PERIPHERY.  GOOD UPPER LEVEL 
DIFFLUENT FLOW NEAR 10N103W ENHANCING DEEP CONVECTION ALONG ITCZ.

WEAKENING SURFACE TROUGH ALONG 122W FROM 06N-10N HAS DIFFLUENT 
FLOW ALOFT E OF AXIS ENHANCING DEEP CONVECTION MENTIONED UNDER 
ITCZ SECTION.

AT THE SURFACE...
HIGH PRES CENTER 1019 MB AT 28N134W EXTENDS RIDGE N OF ITCZ 
ACROSS ENTIRE E PAC.  RIDGE WEAKENS TO 1017 MB AND DRIFT S 
FORCED BY COLD FRONT ENTERING NW CORNER OF BASIN WITHIN 48 HR. 

$$
WALLY BARNES