000
AXPZ20 KNHC 210310
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED APR 21 2010

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 
0200 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE WAS ANALYZED FROM 06N77W TO 
08N98W TO 07N115W TO 05N121W TO 04N140W. ISOLATED MODERATE 
CONVECTION WAS WITHIN 45 NM S AND N OF THE ITCZ AXIS TO THE 
COAST W OF 86W. SCATTERED MODERATE CONVECTION WAS WITHIN 120 NM 
S AND 45 NM N OF THE ITCZ AXIS BETWEEN 127W AND 134W. A TROUGH 
IS EMBEDDED IN THE ITCZ FROM 12N114W TO 02N118W. IT HAD 
SCATTERED MODERATE TO STRONG CONVECTION WITHIN 120 NM E AND 210 
NM W OF THE TROUGH FROM 05N TO 08N AS WELL AS SCATTERED MODERATE 
CONVECTION WITHIN 390 NM W OF THE TROUGH S OF 05N.

...DISCUSSION...

AN AMPLIFIED MID TO UPPER LEVEL TROUGH OVER THE AREA N OF 23N 
AND EXTENDING ALONG THE W COAST OF THE U.S. WILL CUT OFF FROM 
THE NORTHERN STREAM AND DRIFT SE INTO THE DESERT SW OVER THE 
NEXT TWO DAYS. AT THE SAME TIME...HIGH PRES WILL BUILD NW OF THE 
AREA. THE 1742 AND 1922 UTC ASCAT PASSES SHOWED 20 TO 25 KT NW 
TO N WINDS BEHIND THE WEAKENING COLD FRONT FROM 30N120W TO NEAR 
23N130W. THE STRONG PRES GRADIENT BETWEEN THIS TROUGH AND THE 
AFOREMENTIONED HIGH PRES WILL CONTINUE TO GENERATE STRONG NW TO 
N WINDS OVER N CENTRAL AND NE WATERS WED AND THU. THIS STRONG 
PRES GRADIENT MAY EXTEND INTO THE GULF OF CALIFORNIA WHERE 
WESTERLY WINDS WILL LIKELY EXCEED 20 KT WITHIN THE RELATIVELY 
SMALL AREAS DOWNWIND OF MOUNTAIN PASSES. TO THE S OF THE 
BUILDING HIGH PRES...THE 1924 UTC ASCAT PASS SHOWED AN AREA OF 
FRESH TO STRONG TRADE WINDS W OF 132W. THE AREA OF TRADE WINDS 
WILL EXPAND EASTWARD THROUGH THU.

THE MOST CONVECTIVELY ACTIVE AREA LIED ALONG A SURFACE TROUGH 
EMBEDDED IN THE ITCZ. THIS TROUGH WAS MENTIONED IN THE ITCZ 
SECTION. THE CONVECTIVE AREA ASSOCIATED WITH THIS TROUGH AS WELL 
AS ALONG THE ITCZ W OF ANOTHER TROUGH FROM 08N127W TO 02N128W 
CORRESPONDS TO A REGION OF UPPER LEVEL DIFFLUENCE BETWEEN THE 
40-70 KT W TO NW JET AND THE 30 TO 50 KT SW TO W JET SEPARATED 
BY A WEAK UPPER LEVEL TROUGH ALONG 120W S OF 15N. THE LOWER 
LEVEL TROUGHING HERE AS WELL AS THE POOL OF MOISTURE WITH 2.00 
INCH PRECIPITABLE WATER VALUES IS EXPECTED TO MIGRATE W OVER THE 
NEXT TWO DAYS. UPPER LEVEL DIFFLUENCE IS EXPECTED TO INCREASE 
HERE AS AN ANTICYCLONE MOVES INTO THE AREA. LOOK FOR CONVECTION 
TO CONTINUE OVER W WATERS ALONG THE ITCZ OVER THE NEXT FEW DAYS 
IN RESPONSE TO THE LOW LEVEL MOISTURE CONVERGENCE COUPLED WITH 
THE DIFFLUENCE ALOFT. FARTHER E...CONVECTION IS NOTED ALONG AND 
N OF THE ITCZ E OF 86W. THIS CONVECTION LIES UNDER THE W EDGE OF 
AN UPPER RIDGE AXIS THAN EXTENDS INTO NORTHERN SOUTH AMERICA. 
THIS RIDGE AXIS WILL BE CONTRACTING E AND WILL BE REPLACED BY 20 
TO 30 KT SOUTHERLY FLOW ALOFT BY THE END OF THE PERIOD ON THE 
EASTERN SIDE OF AN UPPER TROUGH BUILDING ALONG 90-95W THU. THIS 
PATTERN ALOFT WILL DIMINISH THE DEEP CONVECTION CURRENTLY IN 
PLACE.

SOUTHERLY SWELLS WITH SEAS TO 8 FT WILL CROSS THE EQUATOR 
BETWEEN 100W AND 120W FOR THE NEXT COUPLE OF DAYS.

$$
SCHAUER