000
AXPZ20 KNHC 242152
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SAT APR 24 2010

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 
2015 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE WAS ANALYZED ALONG 07N77W TO 
05N86W TO 07N120W TO 05N134W TO 04N140W. .NUMEROUS MODERATE TO 
STRONG CONVECTION WAS WITHIN 390 NM NE QUADRANT OF 1008 MB LOW 
PRES NEAR 05N86W ON THE E EDGE OF THE ITCZ. SCATTERED MODERATE 
WITH ISOLATED STRONG CONVECTION WAS ELSEWHERE WITHIN 120 NM 
EITHER SIDE OF ITCZ AXIS E OF 83W AS WELL AS WITHIN 330 NM N OF 
THE ITCZ AXIS BETWEEN 88W AND 95W. A TROUGH IS EMBEDDED IN THE 
ITCZ FROM 08N133W TO 02N138W. SCATTERED MODERATE CONVECTION WAS 
WITHIN 330 NM E OF THE TROUGH AND 150 NM W OF THE TROUGH N OF 
04N.

...DISCUSSION...
THE PRES GRADIENT BETWEEN 1003 MB LOW PRES OVER CENTRAL MEXICO 
NEAR 21N100W ON THE TAIL END OF A COLD FRONT THAT REACHES N INTO 
THE MISSISSIPPI VALLEY AND A RIDGE AXIS THAT EXTENDS SW TO NEAR 
10N107W FROM A 1032 MB HIGH CENTERED AT 32N134W IS PRODUCING 20 
TO 25 KT WINDS ALONG THE MEXICAN COAST NEAR MANZANILLO. SHIP 
A8PQ7 REPORTED 23 KT NE TO N WINDS AT 1500 UTC NEAR 19N105W. 
WINDS HERE ARE EXPECTED TO DIMINISH BELOW 20 KT SAT NIGHT AS THE 
COLD FRONT PULLS AWAY. IN ADDITION...THE AFOREMENTIONED HIGH 
PRES SYSTEM WILL WEAKEN AS AN UPPER LEVEL TROUGH PASSES THROUGH 
N WATERS OVER IT AND A STRONG COLD FRONT IMPINGES UPON IT FROM 
THE W. THIS WILL SEND THE DISSIPATING HIGH CENTER S INTO 
FORECAST WATERS SUN NIGHT. WHAT REMAINS OF THE HIGH WILL MERGE 
WITH STRONGER HIGH PRES TO THE W ON MON. THE 1802 UTC ASCAT AND 
1512 UTC WINDSAT PASSES SHOW FRESH TO STRONG TRADES OVER W 
WATERS PRIMARILY BETWEEN 07N AND 21N. THE TRADES WILL SHRINK IN 
AREA SIGNIFICANTLY SUN AS THE HIGH PRES TO THE N WEAKENS AND 
WILL REMAIN W OF 135W MON. MEANWHILE...A 100 KT SOUTHWESTERLY 
UPPER JET ON THE LEADING EDGE OF THE TROUGH OVER N WATERS IS 
TRANSPORTING UPPER LEVEL MOISTURE MANIFESTED AS CIRRUS 
NORTHEASTWARD THROUGH NW WATERS. LOOK FOR THE CIRRUS SHIELD TO 
SHIFT E WITH THE UPPER TROUGH AND ITS ASSOCIATED JET THROUGH MON.

THE LOW LEVEL CYCLONIC GYRE OVER SE WATERS CONTINUES TO SUPPORT 
A 1008 MB SURFACE LOW PRES SYSTEM NEAR 05N86W. THE 1442 ASCAT 
PASS SHOWED 20 TO 25 KT S TO SW WINDS FEEDING INTO THE GYRE. 
SATELLITE PRECIPITABLE WATER VALUES ARE AT OR ABOVE 2.5 INCHES 
IN MUCH OF THE AREA E OF 90W...ALLOWING FOR PLENTY OF LOW LEVEL 
MOSITURE TO CONVERGE ALONG THE ITCZ. WHILE THIS LOW IS QUICKLY 
BECOMING SHEARED BY STRONG E TO SE WINDS ALOFT...STRONG 
CONVECTION IS EXPECTED TO REMAIN OVER THE AREA E OF 85W. AN 
UPPER LEVEL ANTICYCLONE THAT CURRENTLY RESIDES OVER EASTERN 
HONDURAS WILL SLOWLY MOVE EASTWARD...MAKING WAY FOR UPPER LEVEL 
FLOW TO BECOME INCREASINGLY DIFFLUENT OVER SE WATERS BETWEEN IT 
AND ANOTHER ANTICYCLONE S OF THE EQUATOR SUN AND MON.

THERE WERE TWO TROUGHS EMBEDDED IN THE ITCZ AT 1800 UTC. THE 
EASTERN TROUGH WAS ALONG 123W FROM 04N TO 11N WHILE THE WESTERN 
TROUGH WAS FROM 08N133N TO 02N138W. THE WESTERN TROUGH LIES 
UNDER AN UPPER LEVEL RIDGE AXIS AND HAS SOME SCATTERED MODERATE 
CONVECTION ASSOCIATED WITH IT. IT ALSO LIES ON THE EASTERN EDGE 
OF A POOL OF LOW LEVEL MOSITURE THAT IS EXPECTED TO MOVE W ALONG 
THE ITCZ. THE UPPER RIDGE AXIS WILL PINCH OFF AN ANTICYCLONE AND 
CARRY IT NE TO NEAR 12N110W BY SUN AFTERNOON INTO A REGION OF 
LESS LOW LEVEL MOISTURE. THEREFORE...LOOK FOR CONVECTION OVER 
THE CENTRAL AND WESTERN ITCZ TO REMAIN MEAGER THROUGH 
MON...ESPECIALLY COMPARED TO SE WATERS.

$$
SCHAUER