000
AXPZ20 KNHC 220959
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 
1005 UTC SUN APR 22 2007

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY 
THROUGH 0945 UTC.

...ITCZ...

AXIS IS ALONG 9N78W 5N85W 10N96W 5N140W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION IS NOTED WITHIN 60 NM OF 8N92W AND 
WEAKENING WITHIN 120 NM OF 6N120W AND 3N140W.

...DISCUSSION...

A SHORTWAVE RIDGE CREST HAS COLLAPSED OVER THE NW PORTION WITH 
ITS AXIS W TO E ALONG 32N140W 32N116W. UPPER MOISTURE 
ACCOMPANIES THE RIDGE OVER THE AREA N OF 28N W OF 122W AND IS 
SPREADING S WITH TIME. AN UPPER CYCLONE HAS CUT OFF NEAR 
22N125W. DRY UPPER AIR IS INDICATED WITHIN 90 NM EITHER SIDE OF 
LINE 32N110W 26N128W AND ELSEWHERE FROM 16N TO 26N W OF 130W AND 
IS WRAPPING INTO THE W SEMICIRCLE OF THE UPPER CYCLONE.     

AN UPPER LEVEL ANTICYCLONE IS JUST SW OF THE AREA AT 4S147W WITH 
ITS ENVELOPE OF ANTICYCLONIC FLOW EXTENDING NE INTO THE 
DISCUSSION AREA AND CRESTING ALONG POINTS 16N140W 10N130W 
1N130W.  ANOTHER UPPER ANTICYCLONE HAS DEVELOPED NEAR 6N115W 
WITH ITS ENVELOPE OF ANTICYCLONIC FLOW DOMINATING THE DEEP 
TROPICS...ROUGHLY S OF 12N BETWEEN 123W AND 103W. THE COMBINED 
UPPER LEVEL DIFFLUENCE PREVIOUSLY ENHANCED ITCZ CONVECTION 
BETWEEN 150W AND 110W WITH SOME OF THE DEBRIS MOISTURE ADVECTED 
S OF THE EQUATOR. A THIN BAND OF UPPER MOISTURE DOES HOWEVER 
RIDE ACROSS THE TROPICAL RIDGE...ALONG 15N140W TO 14N124W WHERE 
IT MERGES WITH DEBRIS MOISTURE FROM CONVECTION NEAR 5N120W. THIS 
COMBINED MOISTURE PLUME MOVES NE SPLITTING NEAR 20N116W WITH ONE 
BRANCH TURNING INTO THE E SEMICIRCLE OF THE CYCLONE AT 22N125W. 
THE OTHER BRANCH TURNS E AND HAS MOVED ACROSS THE BAJA PENINSULA 
S OF 28N BUT APPEARS TO EVAPORATE IN VERY DRY UPPER AIR 
DOMINATING THE UPPER LEVELS OVER OLD MEXICO W OF 90W.  
  
AN UPPER ANTICYCLONE IS ESTIMATED NEAR 11N75W WITH A MID TO 
UPPER LEVEL RIDGE EXTENDING NW TO BEYOND 32N94W INTO AN UPPER 
RIDGE THAT DOMINATES THE MISSISSIPPI VALLEY OF THE CONUS. THIS 
LARGE RIDGE IS SHRINKING WITH TIME AS A UPPER TROUGH DIGS S 
ALONG THE EASTERN SEABOARD OF THE CONUS AND A VIGOROUS TROUGH 
MOVES ONSHORE THE WESTERN N AMERICA.  

AN TROPICAL UPPER TROUGH EXTENDS S FROM 9N100W TO NEAR 7S104W 
AND EFFECTIVELY SPLITS THE TROPICAL ANTICYCLONIC FLOW DESCRIBED 
ABOVE. WEAK UPPER DIFFLUENCE IS ENHANCING ITCZ CONVECTION NEAR 
10N93W AND EARLIER NEAR 7N84W. THE RESULTANT DEBRIS MOISTURE 
REMAINS IN THE TROPICAL PAC. 

$$
NELSON