000
AXPZ20 KNHC 202158
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE APR 20 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 
2000 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE WAS ANALYZED FROM 06N77W TO 
08N100W TO 07N115W TO 05N122W TO 04N140W. SCATTERED MODERATE TO 
STRONG CONVECTION WAS WITHIN 45 NM EITHER SIDE OF THE ITCZ AXIS 
BETWEEN 83W AND 85W. SCATTERED MODERATE CONVECTION WAS FROM 90 
NM TO 240 NM S OF THE ITCZ AXIS BETWEEN 120W AND 127W. ISOLATED 
MODERATE CONVECTION WAS N OF ITCZ TO THE COAST E OF 85W. A 
TROUGH IS EMBEDDED IN THE ITCZ FROM 10N115W TO 02N117W AND 
SCATTERED MODERATE CONVECTION WAS WITHIN 120 NM E AND 210 NM W 
OF THE TROUGH S OF 07N.

...DISCUSSION...

AN AMPLIFIED 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 1434 UTC 
WINDSAT PASS SHOWED A SOLID AREA OF 20 TO 25 KT NW TO N WINDS 
BEHIND THE DISSIPATING COLD FRONT FROM 30N122W TO 23N130W. THE 
STRONG PRES GRADIENT BETWEEN THIS TROUGH AND THE HIGH PRES WILL 
CONTINUE TO GENERATE STRONG N WINDS OVER N CENTRAL WATERS WED 
AND WEAKEN A NOTCH AS THE STRONGEST GRADIENT MOVES THE NE TO N 
WINDS INTO NE WATERS N OF 25N 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 SOUTH OF THE BUILDING HIGH PRES LIED 
AN AREA OF FRESH TRADE WINDS W OF 132W. THE TRADES WILL EXPAND 
EASTWARD AND INCREASE TO 25 KT THROUGH THU. 

THE MOST CONVECTIVELY ACTIVE AREA LIED S OF THE ITCZ ROUGHLY 
BETWEEN TWO SURFACE TROUGHS EMBEDDED IN THE ITCZ. THE EASTERN 
TROUGH WAS MENTIONED IN THE ITCZ SECTION AND HAD CONVECTION 
CONCENTRATED ALONG ITS AXIS. THE WESTERN TROUGH WAS FROM 09N126W 
TO 02N128W. THIS CONVECTIVE AREA 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 122W S OF 12N. 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 
85W. 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 WILL 
DIMINISH THE CONVECTION CURRENTLY IN PLACE.

SOUTHERLY SWELLS WITH SEAS TO 8 FT WILL CROSS THE EQUATOR 
BETWEEN 100W AND 123W FOR THE NEXT COUPLE OF DAYS.

$$
SCHAUER