000
AXPZ20 KNHC 202125
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI MAY 20 2011

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 
2130 UTC.
 
...ITCZ...
AXIS ALONG 11N86W TO 13N95W TO 08N110W TO 06N135W TO 05N140W. 
SCATTERED MODERATE ISOLATED STRONG WITHIN 150 NM S OF AXIS 
BETWEEN 90W AND 102W AND WITHIN 120 NM EITHER SIDE OF AXIS W OF 
130W. SCATTERED MODERATE WITHIN 180 NM EITHER SIDE OF AXIS 
BETWEEN 106W AND 110W. 

...DISCUSSION...

AT THE UPPER LEVELS A FAIRLY EXTENSIVE BUT E-W ORIENTED 
ANTICYCLONE CENTERED NEAR 12N108W DOMINATES THE DISCUSSION AREA 
E OF 125W AND IS SEPARATED FROM ANOTHER ANTICYCLONE N OF THE 
HAWAIIAN ISLANDS NEAR 27N157W BY A SHARP UPPER LEVEL TROUGH 
WHICH EXTENDS FROM 30N129W SW TO A BASE NEAR 08N143W. DIFFLUENT 
UPPER LEVEL SW FLOW BETWEEN THE TROUGH AND THE EASTERN 
ANTICYCLONE WAS ENHANCING ITCZ CONVECTION BETWEEN 130W AND 142W 
AND ADVECTING MID TO UPPER LEVEL MOISTURE NORTHWARD TOWARD BAJA 
CALIFORNIA.  

AT THE SURFACE...HIGH PRESSURE 1027 MB IS CENTERED JUST N OF THE 
AREA NEAR 32N134W WITH RIDGE EXTENDING SE THROUGH 23N120W TO 
NEAR 14N107W. THE PRESSURE GRADIENT BETWEEN THE RIDGE AND LOW 
PRESSURE OVER THE SW UNITED STATES AND MEXICO IS SUPPORTING 20 
KT WINDS WITHIN 120 NM OF THE WEST COAST OF BAJA CALIFORNIA N OF 
22N. A 1344 UTC WINDSAT PASS CONFIRMED THE EXISTENCE OF THE NW 
WINDS. A SHIP WITH CALL SIGN WDC6698 NEAR THE SOUTHERN TIP OF 
BAJA CALIFORNIA AND ANOTHER WITH SHIP CALL SIGN DEHZ 25.5N114W 
BOTH REPORTED NW WINDS OF 20 KT AT 1800 UTC.

ADDITIONALLY THE PRESSURE GRADIENT BETWEEN THE RIDGE AND LOWER 
PRESSURE NEAR THE ITCZ IS SUPPORTING FRESH 20 KT TRADES FROM 
FROM 07N TO 16N W OF 130W. THIS WAS CONFIRMED BY A 1520 UTC 
WINDSAT PASS. WITH THE SURFACE RIDGE EXPECTED TO REMAIN OVER THE 
SAME GENERAL AREA OVER THE NEXT FEW DAYS...THE FRESH 20 KT WINDS 
ARE EXPECTED TO REMAIN OVER THESE AREAS OVER THE NEXT COUPLE OF 
DAYS. 

SUBSIDING CROSS-EQUATORIAL S TO SW SWELLS WILL CONTINUE TO MOVE 
THROUGH MOST OF EPAC BASIN THROUGH THIS EVENING BEFORE BEING 
REINFORCED BY ANOTHER PULSE OF MODERATE SW SWELL SAT AND SUN. 
NW SWELL TRAIN ENTERS THE FAR NW PORTION OF THE AREA LATE SAT 
AND COVERS THE AREA N OF 20N W OF 125W BY LATE SUN.

$$
COBB