000
AXPZ20 KNHC 190953
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC WED AUG 19 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 
0930 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS N OF 04N ALONG 81W AND IS MOVING W AT AN 
ESTIMATED 22 KT. ISOLATED TSTMS ARE CURRENTLY FLARING OVER 
CENTRAL AMERICA AND THE CARIBBEAN FROM 07N TO 13N.
 
A TROPICAL WAVE IS ANALYZED N OF 06N ALONG 103W WITH WESTWARD 
MOTION OF 15 KT OVER THE PAST 72 HOURS. SLIGHT CYCLONIC TURNING 
IS NOTED ALONG THE WAVE AXIS AT 09N. A COUPLE OF TSTMS VERIFIED 
BY LIGHTNING DATA IS NOTED AT THE MEXICAN COAST AT 18N.

A TROPICAL WAVE IS ANALYZED N OF 06N ALONG 115W AND HAS BEEN 
MOVING W AT 15 KT OVER THE PAST 96 HOURS. ISOLATED MODERATE AND 
STRONG CONVECTION IS NOTED WITHIN 120 NM E OF THE WAVE AXIS FROM 
08N TO 12N.

A TROPICAL WAVE IS ANALYZED FROM 04N TO 16N ALONG 131W BASED ON 
THE CONTINUITY OF WESTWARD MOTION OF 15 KT OVER THE PAST SEVERAL 
DAYS. HOWEVER...CONVECTION APPEARS TO BE INCREASING WELL E OF 
THIS ESTIMATED WAVE POSITION WITH BROAD CYCLONIC ROTATION 
CENTERED ON 11N126W. UPPER LEVEL DIFFLUENCE IS ENHANCING 
CONVECTION AS FAR N OF THE ITCZ AS 14N125W.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE WAS ANALYZED ALONG 07N77W TO 
11N103W TO 10N120W TO 12N128W TO 09N140W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION IS NOTED WITHIN 90 NM EITHER SIDE OF 
A LINE FROM 05N88W TO 08N101W TO 11N121W AND ALSO WITHIN 150 NM 
EITHER SIDE OF A LINE FROM 15N125W TO 07N133W TO 08N140W.

SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED N OF THE 
ITCZ WITHIN 90 NM OF THE PACIFIC COAST OF CENTRAL AMERICA FROM 
80W TO 92W. 

...DISCUSSION...

AN UPPER LEVEL ANTICYCLONE IS CENTERED AT 28N136W WITH A RIDGE 
EXTENDING SW TO A SHARP CREST AT 16N147W AND A RIDGE EXTENDING 
NE TO 31N128W. A SECOND UPPER ANTICYCLONE IS CENTERED AT 22N117W 
WITH A RIDGE SW TO 13N127W AND A RIDGE NE TO OVER THE GULF OF 
CALIFORNIA AT 28N112W. SQUEEZED BETWEEN THE UPPER ANTICYCLONES 
IS AN UPPER TROUGH ALONG POINTS 31N120W TO 25N126W TO 17N129W TO 
A BASE AT 11N133W. DEBRIS MOISTURE FROM ITCZ CONVECTION BETWEEN 
120W AND 129W IS ADVECTED N UNDER THE EASTERN ANTICYCLONE TO 
NEAR 24N123W WHERE IT EVAPORATES. DEBRIS MOISTURE ORIGINATING 
FROM CONVECTION OVER NW OLD MEXICO AT 29N109W IS SPREADING S 
ALONG THE W COAST OF OLD MEXICO AND OVER THE TROPICAL PACIFIC 
FROM 23N TO 10N BETWEEN 106W AND 114W. OTHERWISE...THE UPPER 
LEVELS ARE VERY DRY N OF 15N W OF 110W.

AN UPPER CYCLONE OVER THE NW CARIBBEAN HAS A TROUGH EXTENDING SW 
ACROSS CENTRAL AMERICA TO 10N90W. BROAD UPPER RIDGING IS NOTED 
ELSEWHERE OVER THE TROPICAL PACIFIC E OF 110W AND IS ENHANCING 
CONVECTION ALONG THE ITCZ BETWEEN 86W AND 103W. THE DEBRIS 
MOISTURE IS ADVECTED SW BUT EVAPORATES ALONG 02N BEFORE CROSSING 
THE EQUATOR.   

AT LOW LEVELS A SURFACE RIDGE EXTENDS INTO THE AREA ALONG 
31N140W TO 11N112W. NW WINDS ARE EXPECTED TO PULSE AT MOSTLY 15 
KT...BUT OCCASIONALLY 20 KT ALONG THE W COAST OF THE BAJA 
PENINSULA FOR THE NEXT FEW DAYS. NE WINDS ARE EXPECTED TO 
INCREASE TO 15 TO 20 KT IN AND DOWNSTREAM OF THE GULF OF 
PAPAGAYO ON THU AND FRI. SOUTHERLY WINDS E OF 125W AND S OF THE 
ITCZ ARE IN THE 15 TO 20 KT RANGE WITH SEAS REACHING A MAX OF 9 
FT IN SW SWELL. 

LONG PERIOD SOUTHERLY SWELLS AT A PERIOD OF 18 SECONDS ARE 
EXPECTED TO REACH THE COAST OF CENTRAL AMERICA S OF THE BAJA 
PENINSULA THU NIGHT...WITH 20 PERIOD SWELLS REACHING SOUTHERN 
CALIFORNIA LATE FRI.

$$
NELSON