000
AXPZ20 KNHC 280317
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC TUE APR 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.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS ALONG 08N83W TO 
05N90W TO 03N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION 
IS NOTED WITHIN 120 NM EITHER SIDE OF LINE FROM 07N88W TO 
04N105W TO 05N125W. SCATTERED MODERATE IS DISSIPATING WITHIN 90 
NM OF 09N134W.
 
...DISCUSSION...

A DEEP LAYERED TROUGH LIES OVER THE SUBTROPICAL PACIFIC ALONG 
154W WITH AN EMBEDDED CYCLONE AT 35N146W WITH A SHORTWAVE TROUGH 
EXTENDING SE INTO THE AREA TO NEAR 31N137W. UPPER MOISTURE IS 
INDICATED N OF 25N W OF 137W AND SPREADING N IN THE CYCLONIC 
UPPER FLOW.

AN UPPER LEVEL ANTICYCLONE IS CENTERED NEAR 08N122W WITH AN 
UPPER RIDGE EXTENDING N ALONG 28N115W AND CRESTING OVER NEW 
MEXICO ATTM. CONVECTION WAS PREVIOUSLY ENHANCED ALONG THE ITCZ 
BETWEEN 120W AND 138W AND THE DEBRIS MOISTURE IS SPREADING N 
UNDER THE RIDGE BETWEEN 115W AND 130W AND 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 30N98W TO A SMALL UPPER 
CYCLONE AT 10N103W TO A TROUGH BASE AT 06N103W. FOR THE MOST 
PART THE UPPER LEVELS APPEAR VERY DRY EITHER SIDE OF THE TROUGH 
AXIS...ROUGHLY N OF 07N BETWEEN 116W AND 92W. AN UPPER 
ANTICYCLONE IS OVER S AMERICA NEAR 05N70W WITH A RIDGE EXTENDING 
NW OVER THE W CARIBBEAN. UPPER DIFFLUENCE OVER THE PACIFIC ITCZ 
IS ENHANCING CONVECTION BETWEEN 90W AND 118W...WITH SOME OF THE 
DEBRIS MOISTURE ADVECTED NE ACROSS CENTRAL AMERICA BETWEEN 84W 
AND 90W 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 
18N106W. NORTHERLY WINDS ALONG THE PACIFIC COAST OF NORTHERN 
BAJA ARE IN THE 20 KT RANGE AND EXPECTED SPREAD S 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