000
AXPZ20 KNHC 271549
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON APR 27 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 
1300 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG A LINE FROM...07N77W 
TO 04N82W TO 05N95W TO 03N115W TO 04N137W. SCATTERED MODERATE 
CONVECTION CAN BE FOUND WITHIN 90 NM S AND 150 NM N OF THE ITCZ 
AXIS FROM 92W TO 104W AND SCATTERED MODERATE WITH ISOLATED 
STRONG CONVECTION LIES WITHIN 330 NM N OF THE ITCZ AXIS FROM 
128W TO 137W.

...DISCUSSION...

AN AMPLIFIED PATTERN IS IN PLAY OVER MUCH OF THE FORECAST AREA 
WITH A DEEP TROUGH CENTERED ALONG 150W...AN UPPER LEVEL 
ANTICYCLONE CENTERED NEAR 10N120W...AND A MEAN TROUGH OVER 
NORTHERN MEXICO.  THE PATTERN W OF 115W SHOULD BECOME MORE 
AMPLIFIED OVER THE NEXT FEW DAYS AS NORTHERN STREAM ENERGY 
RELOADS THE TROUGH AXIS NEAR 150W AND NUDGES IT EASTWARD INTO 
WESTERN FORECAST WATERS THE SECOND HALF OF THE WEEK.  THIS WILL 
CAUSE THE ANTICYCLONE TO ITS SE TO STRENGTHEN AND SHIFT SLIGHTLY 
NORTHWARD.  IN TURN...THE ENHANCED NORTHERLY UPPER LEVEL FLOW ON 
THE EASTERN EDGE OF THE ANTICYCLONE WILL ALLOW THE TROUGHING 
OVER MEXICO TO DIG SOUTHWARD...WITH A CUT OFF UPPER LOW EXPECTED 
NEAR 10N100W LATE TUE/EARLY WED.  

THE ASCAT PASS FROM 0706 UTC SHOWS SE WINDS TO 25 KT OVER FAR NW 
WATERS ON THE EASTERN SIDE OF THE DEEP LAYER TROUGH ALONG 150W.  
THESE WINDS ARE EXPECTED TO ABATE SOMEWHAT TOMORROW...BUT LOOK 
FOR THE SOUTHEASTERLY FLOW TO EXPAND ON WED AS THE UPPER TROUGH 
IS RELOADED WITH NORTHERN STREAM ENERGY.

THE ASCAT PASS FROM 0524 UTC SHOWED WINDS TO 25 KT ALONG THE 
COAST OF BAJA CALIFORNIA...INDUCED BY THE PRES GRADIENT BETWEEN 
SURFACE TROUGHING OVER NE MEXICO AND THE SFC RIDGE OVER N WATERS 
ALONG 130W.  THIS OBSERVATION IS CONFIRMED BY SHIP V20V6.  BOTH 
THE TROUGHING OVER NE MEXICO AND THE RIDGE ARE EXPECTED TO 
WEAKEN THROUGH TUE. ON WED...LOOK FOR THE RIDGE AXIS TO SHIFT 
EASTWARD OFF BAJA CALIFORNIA AS TROUGHING BUILDS IN THE LEE OF 
THE ROCKIES...ALLOWING STRONG WINDS TO RETURN OFF THE W COAST OF 
BAJA CALIFORNIA.

GAP WINDS...
STRONG CARIBBEAN TRADE WINDS CONTINUE TO SEEP THROUGH COSTA RICA 
AND NICARAGUA THROUGH THE GULF OF PAPAGAYO WHERE THE 0338 UTC 
ASCAT PASS SHOWED WINDS TO 25 KT. THE RIDGE OFF THE MID ATLC 
U.S. COAST IS EXPECTED TO GRADUALLY WEAKEN AND LIFT NORTHWARD 
LATER IN THE WEEK.  FOR NOW...LITTLE CHANGE IN CONDITIONS IS 
EXPECTED.

CONVECTION...
IN ADDITION TO THE CONVECTION ALONG THE ITCZ....SCATTERED 
MODERATE CONVECTION CAN BE FOUND WITHIN 150 NM OF 06N108W AND 
FROM 04N TO 07N BETWEEN 116W AND 121W.  THIS CONVECTION LIES IN 
A REGION OF BROAD UPPER LEVEL DIFFLUENCE BETWEEN THE 
AFOREMENTIONED ANTICYCLONE NEAR 10N120W AND THE UPPER LEVEL 
TROUGH EXTENDING FROM NORTHERN MEXICO SOUTHWARD ALONG 100W.  

STRONGER CONVECTION AND UPPER LEVEL DIFFLUENCE CAN BE FOUND E OF 
THE TROUGH AXIS ALONG 140W FROM 03N TO 09N...WITH SCATTERED 
MODERATE WITH ISOLATED STRONG CONVECTION WITHIN 330 NM N OF THE 
ITCZ AXIS FROM 128W TO 137W. THIS CONVECTION LIES IN THE REAR 
RIGHT QUADRANT OF THE UPPER JET ON THE EASTERN EDGE OF THE DEEP 
LAYER TROUGH ALONG 150W AND COINCIDES WITH THE SPLIT IN UPPER 
LEVEL FLOW AROUND THE ANTICYCLONE NEAR 10N120W.  WITH THE 
PATTERN EXPECTED TO BE SLOW TO CHANGE HERE...THIS REGION SHOULD 
BE THE MOST LIKELY AREA FOR CONVECTION OVER FORECAST WATERS FOR 
THE NEXT DAY OR TWO.

$$
SCHAUER CLARK