000
AXPZ20 KNHC 280311
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC TUE JUL 28 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 EXTENDS FROM 04N TO 13N ALONG 108W AND HAS BEEN 
MOVING W AT 15 KT. SCATTERED MODERATE AND ISOLATED STRONG 
CONVECTION IS CURRENTLY ENHANCED FROM 08N TO 14N BETWEEN 105W 
AND 111W. 

A TROPICAL WAVE FROM 04N TO 17N ALONG 126W HAS MOVED W AROUND 15 
KT. THE WAVE IS MOVING UNDER AN UPPER RIDGE WITH THE ASSOCIATED 
DIFFLUENCE ENHANCING A LARGE AREA OF SCATTERED MODERATE AND 
ISOLATED STRONG CONVECTION OVER THE PACIFIC FROM 07N TO 15N 
BETWEEN 121W AND 128W. 

A TROPICAL WAVE EXTENDS FROM 04N TO 12N ALONG 134W AND HAS MOVED 
W AT ABOUT 15 KT OVER THE PAST 24 HOURS. THE WAVE IS MOVING 
THROUGH AN AREA THAT HAS SOMEWHAT UNFAVORABLE UPPER SUPPORT WITH 
CONVECTION SUPPRESSED N OF 10N BUT ENHANCED BUT SHEARED FROM 06N 
TO 10N BETWEEN 131W AND 135W. 

...ITCZ...
THE AXIS EXTENDS ALONG POINTS 07N77W TO 06N81W TO 12N118W T0 
07N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED 
FROM 04N TO 08N E OF 85W AND ALSO WITHIN 150 NM OF A LINE FROM 
16N101W TO 10N118W AND FROM 07N TO 14N BETWEEN 121W TO 131W AND 
WITHIN 150 NM OF 08N134W.

...DISCUSSION...
AN UPPER LEVEL RIDGE POKES E INTO THE SW CORNER ALONG 09N W OF 
138W. A MID TO UPPER LEVEL CYCLONE N OF THE AREA IS NEAR 36N138W 
WITH A TROUGH S ALONG TO A BASE AT 14N139W. CYCLONIC FLOW 
DOMINATES THE UPPER LEVELS N OF 16N W OF 125W WITH DEBRIS 
MOISTURE EVAPORATING N OF 27N W OF 131W...WHILE DRY AIR IS 
OBSERVED ELSEWHERE WITHIN THE TROUGH. 

AN UPPER ANTICYCLONE IS CENTERED OVER NORTHWESTERN OLD MEXICO AT 
29N110W WITH ITS ANTICYCLONIC CIRCULATION DOMINATING THE AREA N 
OF 22N BETWEEN 98W AND 120W. AN UPPER TROUGH EXTENDS SW ACROSS 
CENTRAL AMERICA INTO THE PACIFIC ALONG 18N104W TO 16N108W TO 
01N113W. CONVECTION IS ENHANCED OVER THE AREA FROM 10N TO 18N 
BETWEEN 98W AND 111W WITH THE DEBRIS MOISTURE ADVECTED NE ACROSS 
THE GULF OF MEXICO AND FLORIDA. 

AN UPPER ANTICYCLONE HAS FORMED NEAR 15N121W AND IS ENHANCING 
CONVECTION BETWEEN 120W AND 132W WITH THE DEBRIS MOISTURE 
ADVECTED N TO NEAR 20N123W. AN UPPER CYCLONE IS OVER THE DEEP 
TROPICS AT 07N87W AND IS MOVING W WITH TIME AND IS NOW BEGINNING 
TO KICK OFF TSTMS NEAR THE CENTER. 
   
GAP WINDS...NE TO E WINDS IN AND DOWNSTREAM OF THE GULF OF 
PAPAGAYO ARE EXPECTED TO CONTINUE FOR AT LEAST A COUPLE MORE 
DAYS. 

$$
NELSON