000
AXPZ20 KNHC 122152
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC THU MAY 12 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 
2100 UTC.

...ITCZ...
AXIS ALONG 11N103W TO 05N140W.  ISOLATED MODERATE CONVECTION 
WITHIN 90 NM N OF AXIS FROM 118W TO 123W. 

...DISCUSSION...
UPPER LEVEL CYCLONIC VORTEX CENTERED AT 27N128W HAS VERY DRY 
TROUGH AXIS EXTEND SW TO 16N140W.  WEAK 85-90 KT JET CORE SE OF 
AXIS ADVECTS MID/UPPER LEVEL MOISTURE TOWARDS SRN BAJA 
CALIFORNIA.  DOWNSTREAM RIDGE ANCHORED BY ANTICYCLONIC GYRE AT 
14N98W ALSO BRINGS ITCZ CONVECTIVE DEBRIS INTO SOUTH CENTRAL 
MEXICO.  NE DRIFT OF GYRE COMBINED WITH WLY DRIFT OF SURFACE
LOW PRES 1011 MB AT 11N103W HAS EFFECTIVELY DECOUPLED THUS 
INCREASING ELY SHEAR OVER LOW PRES DECREASING CONVECTION 
SIGNIFICANTLY AND WEAKENING SYSTEM AS PREDICTED BY MODEL 
GUIDANCE.

ELSEWHERE AT THE SURFACE...
WEAK COLD FRONT APPROACH NW CORNER OF BASIN BUT RUN OUT OF 
ENERGY AS UPPER LEVEL SUPPORT SHIFT NE.  RIDGE BUILDS AS FRONT 
DISSIPATES AND TIGHTENS PRES GRADIENT EFFECTIVELY INCREASING NE 
TRADES TO A FRESH BREEZE.  MEANWHILE MODERATE NW WINDS ALONG W 
COAST OF BAJA CALIFORNIA DIMINISH LEAVING 8 FT SWELLS N OF 27N E 
OF 125W FOR NEXT 6 HRS.  

WHILE AFOREMENTIONED LOW PRES 1011 MB AT 11N103W MAINTAINS A 
GOOD LOW LEVEL SWIRL...IT REMAINS EMBEDDED IN ITCZ WITH LITTLE 
OR NO ORGANIZATION AND FACING INCREASINGLY ADVERSE UPPER LEVEL 
ENVIRONMENT.  CONSEQUENTLY...CONVECTION IS EXPECTED TO PHASE OUT 
AND FEATURE WEAKEN. 

$$
WALLY BARNES