000
AXPZ20 KNHC 201522
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI MAY 20 2011

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1530 UTC.
 
...ITCZ...
AXIS ALONG 13N88W TO 13N97W TO 06N110W TO 04N140W. SCATTERED 
MODERATE ISOLATED STRONG WITHIN 150 NM S OF AXIS BETWEEN 90W AND 
102W...WITHIN 150 NM EITHER SIDE OF AXIS BETWEEN 110W AND 
120W...AND WITHIN 90-120 NM EITHER SIDE OF AXIS W OF 130W.  

...DISCUSSION...

AT THE UPPER LEVELS A FAIRLY EXTENSIVE ANTICYCLONE CENTERED NEAR 
12N110W DOMINATES THE DISCUSSION AREA E OF 125W AND IS SEPARATED 
FROM ANOTHER ANTICYCLONE N OF THE HAWAIIAN ISLANDS NEAR 28N158W 
BY A SHARP UPPER LEVEL TROUGH WHICH EXTENDS FROM 30N130W SW TO A 
BASE NEAR 08N145W. DIFFLUENT UPPER LEVEL S TO 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 1025 MB IS CENTERED JUST N OF THE 
AREA NEAR 33N134W 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 SHIP WITH CALL SIGN WDC6698 REPORTED NW WINDS OF 20 KT 
AND SEAS OF 9 FT NEAR THE SOUTHERN TIP OF BAJA AT 1200 UTC.

ADDITIONALLY THE PRESSURE GRADIENT BETWEEN THE RIDGE AND LOWER 
PRESSURE NEAR THE ITCZ IS SUPPORTING FRESH 20 KT TRADES FROM 
FROM 07N TO 15N W OF 130W AS DEPICTED BY THE LATEST ASCAT 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