000
AXPZ20 KNHC 120248
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU MAY 12 2011

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0300 UTC.

...ITCZ...
AXIS ALONG 09N84W TO 08N95W TO 09N106W TO 06N127W TO 06N135W.   
SCATTERED MODERATE CONVECTION WITHIN 120 NM OF AXIS FROM 99W TO
107W.

...DISCUSSION...
LARGE UPPER LEVEL CYCLONIC VORTEX NEAR FOUR CORNERS REGION IN SW 
CONUS HAS TROUGH EXTEND TO SECOND VORTEX AT 24N133W.  VERY DRY 
SUBSIDING AIR MASS WITHIN 300 NM OF TROUGH AXIS. TROUGH FLATTENS 
CREST OF DOWNSTREAM RIDGE CENTERED IN ANTICYCLONIC GYRE AT 
13N104W BUT RIDGE DOES NOT MOVE.  GYRE PROVIDES FAVORABLE AREA 
OF DIFFLUENT OUTFLOW AND MINIMAL SHEAR TO STATIONARY SURFACE LOW 
PRES 1009 MB AT 09N102W ENHANCING SCATTERED DEEP CONVECTION 
WITHIN 180 NM OF LOW PRES NW QUADRANT AND ALONG ITCZ.

MODEL GUIDANCE DO NOT FAVOR DEVELOPMENT AS LOW PRES STARTS 
DRIFTING W WHILE GYRE MOVES N-NE.  FORECAST CALLS FOR CONVECTION 
TO CONTINUE FOR NEXT 12-18 HRS THEN DECREASE AS FEATURES SPLIT 
APART AND LOW PRES ENTERS A MORE ADVERSE UPPER ENVIRON.    

AT THE SURFACE...
PREVIOUS RIDGE DISSIPATED AS COLD FRONT APPROACHES BASIN FROM 
NW.  WITH RELAXING PRES GRADIENT...PRESENT FRESH NW WINDS WITHIN 
120 NM OF BAJA CALIFORNIA W COAST WILL DIMINISH UNDER 20 KT AND 
SEAS SUBSIDE UNDER 8 FT WITHIN 12 HRS.  

STRING OF THREE WEAK LOW PRES CENTERS ALONG ITCZ DO NOT PRESENT 
ANY THREAT OF ORGANIZATION DESPITE FAVORABLE ENVIRONMENT ALOFT.  

$$
WALLY BARNES