000
AXPZ20 KNHC 272157
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC MON APR 27 2009

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1300 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS ALONG 09N84W TO 
05N100W TO 02N120W TO 05N140W. SCATTERED MODERATE AND ISOLATED 
STRONG CONVECTION IS NOTED WITHIN 150 NM EITHER SIDE OF LINE 
FROM 05N92W TO 06N110W AND ALSO WITHIN 90 NM OF 06N116W AND 
WITHIN THE AREA BOUNDED BY 04N TO 08N BETWEEN 130W AND 136W.

...DISCUSSION...

A DEEP LAYERED TROUGH LIES OVER THE SUBTROPICAL PACIFIC ALONG 
150W WITH AN EMBEDDED CYCLONE AT 34N147W WITH A SHORTWAVE TROUGH 
EXTENDING SE INTO THE AREA TO NEAR 27N136W. UPPER MOISTURE IS 
INDICATED N OF 23N W OF 130W AND SPREADING N IN THE CYCLONIC 
UPPER FLOW.

AN UPPER LEVEL ANTICYCLONE IS CENTERED NEAR 08N120W WITH AN 
UPPER RIDGE EXTENDING N ALONG 30N120W AND CRESTING OVER SW 
ARIZONA ATTM. CONVECTION ALONG THE ITCZ BETWEEN 120W AND 135W IS 
ENHANCED BY THE UPPER DIFFLUENCE AND THE DEBRIS MOISTURE IS 
SPREADING N UNDER THE RIDGE BETWEEN 120W AND 130W EVENTUALLY 
FANNING OUT OVER THE SW CONUS.

THE CENTRAL PORTION OF THE DISCUSSION AREA IS DOMINATED BY A MID 
TO UPPER TROUGH WITH ITS MEAN AXIS FROM 30N102W TO A SMALL UPPER 
CYCLONE AT 10N102W TO A TROUGH BASE AT 07N102W. FOR THE MOST 
PART THE UPPER LEVELS APPEAR VERY DRY EITHER SIDE OF THE TROUGH 
AXIS...ROUGHLY N OF 07N BETWEEN 116W AND 87W. AN UPPER 
ANTICYCLONE IS OVER S AMERICA AT 06N65W WITH A RIDGE EXTENDING 
NW OVER THE W CARIBBEAN. UPPER DIFFLUENCE OVER THE PACIFIC ITCZ 
IS ENHANCING CONVECTION BETWEEN 90W AND 112W...WITH SOME OF THE 
DEBRIS MOISTURE ADVECTED NE ACROSS CENTRAL AMERICA BETWEEN 84W 
AND 94W AND ACROSS THE W PERIPHERY OF THIS UPPER RIDGE WITH THE 
MOISTURE NOW SPREADING E ACROSS THE SOUTHERN BAHAMAS. 

AT THE LOW LEVELS A RIDGE EXTENDS INTO THE AREA FROM 32N131W TO 
12N97W. NORTHERLY WINDS ALONG THE PACIFIC COAST OF BAJA ARE IN 
THE 20 KT RANGE AND EXPECTED TO CHANGE LITTLE THROUGH 48 HOURS. 
TRADE WINDS SW OF THE SURFACE RIDGE ARE ABOUT 20 KT BUT THE 
OVERALL AREA IS EXPECTED TO DIMINISH OVER THE NEXT FEW DAYS.  
SOUTHERLY WINDS OVER THE EXTREME NW PORTION ARE EXPECTED TO 
CONTINUE FOR ANOTHER 48 HOURS IN ASSOCIATION WITH THE DEEP 
LAYERED CYCLONE NEAR 34N147W.      

GAP WINDS...
NE WINDS ARE EXPECTED PULSE AT 20-25 KT IN AND DOWNSTREAM OF THE 
GULF OF PAPAGAYO THROUGH 48 HOURS.

$$
NELSON