000
AXPZ20 KNHC 121547
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE MAY 12 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 
1500 UTC.

...ITCZ...
AXIS ALONG A LINE FROM 08N78W TO 08N87W TO 12N102W TO 05N132W TO 
04N140W. SCATTERED MODERATE ISOLATED STRONG WITHIN 60 NM S OF 
AXIS BETWEEN 81W AND 84W. SCATTERED MODERATE ISOLATED STRONG 
WITHIN 180 NM S OF AXIS BETWEEN 87W AND 89W. SCATTERED MODERATE 
WITHIN 60 NM N OF AXIS BETWEEN 112W AND 115W.

...DISCUSSION...
AN AMPLIFIED UPPER PATTERN REMAINS IN PLACE WITH A BROAD UPPER 
TROUGH PERSISTING MAINLY N OF 15N AND W OF 120W...AN UPPER RIDGE 
OFF ACAPULCO MEXICO NEAR 14N100W...AND A WEAK UPPER TROUGH 
EXTENDING NE TO SW FROM HONDURAS TO ROUGHLY 08N90W. DIVERGENT 
FLOW ALOFT BETWEEN THE BROAD UPPER TROUGH AND THE UPPER 
ANTICYCLONE IS ENHANCING CONVECTION ALONG THE ITCZ BETWEEN 112W 
AND 115W. SIMILARLY DIVERGENT FLOW ON THE EAST SIDE OF THE UPPER 
TROUGH OVER CENTRAL AMERICA IS AIDING CONVECTIVE DEVELOPMENT 
ALONG THE ITCZ BETWEEN 81W AND 84W...AND 87W AND 89W. IN 
ADDITION...A RESIDUAL LINE OF CONVECTION IS EVIDENT OFF THE 
MEXICAN COAST FROM ACAPULCO TO THE GULF OF 
TEHUANTEPEC...ENHANCED BY NORTHERLY DIVERGENT FLOW BETWEEN THE 
UPPER ANTICYCLONE AND THE UPPER TROUGH TO THE EAST.

FURTHER SOUTH...A 12Z QUIKSCAT PASS SHOWED 20 TO 25 KT FLOW 
THROUGH THE GULF OF PAPAGAYO...THE RESULT OF FRESH TO STRONG 
TRADE WIND FLOW FILTERING THROUGH THE CARIBBEAN...WITH THE ADDED 
IMPACT OF DRAINAGE FLOW OFF THE COSTA RICAN MOUNTAINS. THESE 
WINDS WILL DIMINISH THIS AFTERNOON...BUT WILL LIKELY REAPPEAR 
WED MORNING. TRADE WIND FLOW OVER THE CARIBBEAN IS EXPECTED TO 
DIMINISH STARTING TOMORROW...ALLOWING THE PAPAGAYO WINDS TO 
DIMINISH AS WELL.

OFF THE NORTHERN BAJA COAST...SHIP AND SCATTEROMETER DATA SHOW 
20 KT NORTHERLY FLOW...BETWEEN THE COAST AND A 1026 MB SURFACE 
HIGH PRES AREA CENTERED NEAR 38N130W. THESE WINDS WILL SPREAD 
DOWN THE BAJA COAST THROUGH WEDNESDAY...ACCOMPANIED BY A RENEWED 
ROUND OF NORTHERLY SWELL TO 10 FT OFF THE FAR NORTHERN BAJA 
COAST.

$$
CHRISTENSEN