000
AXPZ20 KNHC 281522
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE APR 28 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 
1430 UTC.

...ITCZ...

INTERTROPICAL CONVERGENCE ZONE LIES ALONG A LINE FROM...03N77W 
TO 05N86W TO 01N100W TO 03N115W TO 03N140W. SCATTERED MODERATE 
CONVECTION CAN BE FOUND WITHIN 120 NM S OF THE ITCZ AXIS E OF 
81W. 
 
...DISCUSSION...

N OF 20N...
THE UPPER PATTERN OVER THE FORECAST AREA N OF 20N WILL GRADUALLY 
BECOME MORE PROGRESSIVE OVER THE NEXT FEW DAYS AS THE DEEP LAYER 
TROUGH E OF HAWAII IS RELOADED WITH NORTHERN STREAM ENERGY AND 
SHOVED EASTWARD INTO NW WATERS...DISLODGING THE RIDGE DOWNSTREAM 
OF THIS TROUGH EASTWARD AS WELL.  AT THE SURFACE...THE TROUGH IS 
EXPECTED TO MOVE INTO NW WATERS WED.  SOUTHERLY WINDS AHEAD OF 
THE TROUGH ARE EXPECTED TO APPROACH 25 KT AND TOTAL PRECIPITABLE 
WATER IMAGERY REVEALS THE TROUGH IS TAPPED INTO TROPICAL 
MOISTURE.  THERE IS AN INCREASING CHANCE FOR CONVECTION OVER NW 
WATERS AHEAD OF THE LOW LEVEL BOUNDARY.  THE ADVANCEMENT OF THIS 
SURFACE SYSTEM WILL FORCE THE RIDGE AXIS EASTWARD...INCREASING 
THE PRES GRADIENT OFF THE BAJA CALIFORNIA COAST AS SURFACE 
TROUGHING SIMULTANEOUSLY BUILDS OVER THE HIGH PLAINS AND N 
CENTRAL MEXICO.

S OF 20N...
THE HIGHLY AMPLIFIED UPPER PATTERN OVER FORECAST WATERS S OF 20N 
WILL PERSIST FOR THE NEXT FEW DAYS WITH A TROUGH AXIS ALONG 98W 
AND AN ANTICYCLONE CENTERED NEAR 10N120W. STRONG SOUTHERLY FLOW 
ON THE EASTERN EDGE OF THE TROUGH IS TRANSPORTING MID TO UPPER 
LEVEL MOISTURE INTO GUATEMALA...EL SALVADOR...AND HONDURAS.  
THIS AREA IS MARKED BY MULTI-LAYERED CLOUDINESS.  THE REAR RIGHT 
QUADRANT OF THIS BROAD SOUTHERLY JET LIES NEAR THE COAST OF 
COLOMBIA WHERE SCATTERED MODERATE WITH ISOLATED STRONG 
CONVECTION CURRENTLY LIES IN THIS REGION OF STRONG UPPER LEVEL 
DIFFLUENCE.  THE DRY...STRONG NORTHERLY FLOW ON THE WESTERN EDGE 
OF THIS TROUGH SHOULD INHIBIT DEEP CONVECTION BETWEEN 100W AND 
110W THE NEXT DAY OR TWO.  FARTHER W...A WEAK LOW TO MID LEVEL 
INVERTED TROUGH NEAR 120W WILL BE A LIKELY FOCUS FOR CONVECTION 
AS IT PASSES W UNDER THE UPPER LEVEL DIFFLUENT REGION ASSOCIATED 
WITH THE SW SIDE OF THE ANTICYCLONE.

GAP WINDS...
THE 1226 UTC QUIKSCAT PASS SHOWS WINDS DOWNSTREAM OF THE GULF OF 
PAPAGAYO IN THE 20 TO 25 KT RANGE.  THESE NE TO E GAP WINDS WILL 
CONTINUE INTO THU.  WINDS WILL DIMINISH AS THE IMPETUS HIGH 
PRESSURE OFF THE MID ATLC U.S. COAST WEAKENS AND SHIFTS 
EASTWARD...WEAKENING THE TRADE WINDS OVER THE SW CARIBBEAN.

$$
SCHAUER CLARK