000
AXPZ20 KNHC 222143
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC THU APR 22 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 
2030 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS WAS ANALYZED FROM 06N77W 
TO 05N102W TO 10N120W TO 06N123W TO 05N140W. SCATTERED MODERATE 
TO STRONG CONVECTION WAS WITHIN 180 NM N AND 120 NM S OF THE 
ITCZ AXIS BETWEEN 110W AND 118W. SCATTERED MODERATE CONVECTION 
WAS WITHIN 150 NM N OF THE ITCZ AXIS BETWEEN 95W AND 100W. 
SCATTERED MODERATE CONVECTION WAS ALSO WITHIN 210 NM S AND 90 NM 
N SEMICIRCLE OF 1008 MB LOW PRES EMBEDDED IN THE ITCZ NEAR 
10N120W.
 
...DISCUSSION...

AN AMPLIFIED MID TO UPPER LEVEL LOW OVER THE U.S. DESERT SW WILL 
DRIFT E THROUGH THE FOUR CORNERS REGION FRI. THE 1840 AND 1700 
UTC ASCAT PASSES SHOWED 20 TO 25 KT NW TO N WINDS OVER NE WATERS 
ASSOCIATED WITH THE PRES GRADIENT BETWEEN THIS TROUGH AND 1031 
MB HIGH PRES NW OF THE AREA NEAR 36N144W. THIS PRES GRADIENT HAS 
ALSO BROUGHT W TO NW WINDS TO 20 KT IN THE NORTHERN GULF OF 
CALIFORNIA...WITH HIGHER WINDS POSSIBLE IN THE RELATIVELY SMALL 
AREAS DOWNWIND OF MOUNTAIN PASSES. SIMILARLY...THE PRES GRADIENT 
S OF THE HIGH BETWEEN IT AND THE ITCZ HAS BROUGHT STRONG 
EASTERLY TRADE WINDS TO W WATERS ACCORDING TO THE 1942 UTC ASCAT 
PASS. THE HIGH PRES SYSTEM IS FORECAST TO CONTINUE TO WEAKEN AS 
IT IS NUDGED EASTWARD OVER THE NEXT TWO DAYS BY A COLD FRONT 
PASSING OVER ITS NW EDGE. AS THE TROUGH OVER THE SW U.S. 
MOVES EAST FRI...LOOK FOR THE PRES GRADIENT TO WEAKEN ENOUGH TO 
BRING WINDS BELOW 20 KT OVER NE WATERS AND THE GULF OF 
CALIFORNIA BY AFTERNOON. TRADE WINDS WILL SHRINK IN AREA FRI IN 
RESPONSE TO THE WEAKENING HIGH PRES TO THE N.

STRONG MOISTURE CONVERGENCE ALONG THE ITCZ BETWEEN THE NE TRADES 
AND STRONG SE TRADES S OF THE EQUATOR HAS PROVIDED FUEL FOR 
CONVECTION BETWEEN 110W AND 125W. A 1008 MB SURFACE LOW EMBEDDED 
IN THE ITCZ NEAR 10N120W HAS FURTHER HELPED POOL LOW LEVEL 
MOISTURE. THE ASCAT PASS FROM 1704 UTC SHOWS TO 20 T0 25 KT 
SOUTHERLY INFLOW IN THE SE QUADRANT OF THE LOW. AN UPPER JET 
WITH WEST-SOUTHWESTERLY WINDS OF 60 KT OR GREATER JUST N OF THE 
SURFACE LOW IS CURRENTLY TRANSPORTING MID TO UPPER LEVEL 
MOISTURE INTO CENTRAL MEXICO. THE PROXIMITY OF THIS JET WILL 
LIKELY INHIBIT ANY DEVELOPMENT OF THE LOW...WITH MOST OF THE 
GUIDANCE CARRYING A SLOW W MOVING TROUGH FRI AND SAT. 
CURRENTLY...A WEAK UPPER RIDGE AXIS LIES S OF THE SURFACE LOW 
AND THE DIFFLUENCE ASSOCIATED WITH IT IS SUPPORTING THE DEEP 
CONVECTION NEAR THE LOW. THE UPPER RIDGE WILL SHIFT E OVER THE 
NEXT TWO DAYS...AWAY FROM THE LOW LEVEL SYSTEM. AS A 
RESULT...CONVECTION IS EXPECTED TO BECOME LESS PREVALENT OVER W 
WATERS THROUGH SAT. 

FARTHER E...AN ANTICYCLONE IS DEVELOPING ALOFT NEAR 07N102W. 
THIS AREA IS CURRENTLY IN A RELATIVE MINIMUM FOR AVAILABLE LOW 
TO MID LEVEL MOISTURE ACCORDING TO SATELLITE PRECIPITABLE WATER 
IMAGERY. A NEW POOL OF MOISTURE HAS MOVED W INTO THE EASTERN 
PACIFIC ALONG THE ITCZ E OF 90W AND WILL SUPPLY SOME FUEL FOR 
INCREASED CONVECTION OVER THE NEXT TWO DAYS TO THE DIFFLUENT 
REGION ASSOCIATED WITH THE DEVELOPING ANTICYCLONE.

FINALLY...THE STRONG SE TRADES SOUTH OF THE EQUATOR ARE HELPING 
THE CAUSE FOR CROSS-EQUATORIAL SWELL WITH WAVES AROUND 8 FT OVER 
S CENTRAL WATERS THROUGH SAT.

$$
SCHAUER