000
AXPZ20 KNHC 220908
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN MAY 22 2011

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0745 UTC.
 
...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE AXIS WAS ANALYZED ALONG 
14N90W TO 10N105W TO 04N120W TO 01N140W. SCATTERED MODERATE TO 
STRONG CONVECTION LIES ON THE EASTERN SIDE OF THE ITCZ FROM 11N 
TO 14N BETWEEN E OF 94W TO THE COAST AND INLAND INTO EL SALVADOR 
AND WESTERN PORTIONS OF HONDURAS AND NICARAGUA. SCATTERED 
MODERATE CONVECTION LIES WITHIN 360 NM S OF THE ITCZ AXIS 
BETWEEN 93W AND 103W AND WITHIN 150 NM N OF THE ITCZ AXIS 
BETWEEN 126W AND 131W. 

...DISCUSSION...
A TROUGH ALOFT EXTENDS FROM AN UPPER LOW NEAR 15N142W THROUGH 
24N136W TO POINT CONCEPTION CALIFORNIA AND INTO THE WESTERN 
UNITED STATES WHERE SURFACE TROUGHING IS ALSO IN PLACE. 
MEANWHILE...A 1031 MB SURFACE HIGH PRES SYSTEM NEAR 35N145W 
EXTENDS A RIDGE INTO THE FORECAST AREA FROM 30N129W TO 14N106W. 
A MODERATE PRESSURE GRADIENT EXISTS BETWEEN THIS RIDGE AND THE 
TROUGHING OVER THE INTERIOR WESTERN UNITED STATES. FRESH NW TO N 
WINDS...AS INDICATED BY SHIP WDC6698 AND THE 0540 UTC ASCAT 
PASS...LIE OVER NE WATERS AS A RESULT. STRONG NW WINDS LIE OVER 
A BROAD AREA NEAR THE CALIFORNIA COAST AS WELL. THESE WINDS N OF 
THE AREA ARE EXPECTED TO REMAIN STRONG THROUGH THE END OF THE 
PERIOD ON EARLY TUE AND NW SWELL WILL KEEP SEAS IN THE ADVISORY 
RANGE OVER NE WATERS. THE MWW3 MODEL IS OVERDONE WITH THE AREAL 
EXTENT OF THE SEAS ABOVE 8 FT ACCORDING TO THE 2010 UTC JASON1 
PASS.

FRESH TRADE WINDS LIE SE OF THE RIDGE AXIS AS INDICATED BY THE 
0220 UTC WINDSAT PASS. LITTLE CHANGE IS EXPECTED IN THESE 
CONDITIONS THROUGH MID DAY MON. HIGH PRES TO THE N WILL BEGIN TO 
WEAKEN AS A COLD FRONT ENCROACHES UPON IT BY MON NIGHT...AND THE 
FRESH TRADES WILL BEGIN TO SHRINK SOUTHWARD. 

A SURFACE TROUGH LIES FROM 09N108W TO 02N111W. NO SIGNIFICANT 
DEEP CONVECTION IS OBSERVED WITH THIS FEATURE. IT APPEARS TO BE 
THE SURFACE REFLECTION OF ENERGY ALOFT THAT IS EXPECTED TO 
GRADUALLY WEAKEN THROUGH MON AS IT MOVES NE. THERE IS A REGION 
OF FRESH SW WINDS JUST SOUTH OF THE ITCZ E OF THIS TROUGH TO 94W 
AS SHOWN BY THE 0314 UTC AND 0454 UTC ASCAT PASSES. THESE WINDS 
ARE EXPECTED TO DIMINISH MON AS THE FORCING ALOFT WEAKENS.

THE 0312 UTC ASCAT PASS CONTINUES TO SHOW FRESH S TO SW WINDS 
LIE S OF 04N TO THE COAST OF ECUADOR. ISOLATED MODERATE 
CONVECTION LIES JUST N OF THE AREA...PRIMARILY N OF 03N E OF 
85W. CURRENTLY...DIFFLUENT FLOW ALOFT LIES OVER FAR SE WATERS 
AND IS ENHANCING CONVECTION. IT IS ANTICIPATED THAT THESE WINDS 
AND CONVECTION WILL DIMINISH BY MON MORNING WITH FLOW ALOFT 
EXPECTED TO BECOME WEAKER AND MORE UNIFORMLY EASTERLY.

$$
SCHAUER