000
AXPZ20 KNHC 240952
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SAT APR 24 2010

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...ITCZ...
AXIS ALONG 05N77W TO 08N91W TO 07N110W TO 04N125W TO 06N140W. 
ISOLATED MODERATE CONVECTION WITHIN 120 NM OF AXIS FROM 91W-103W 
AND WITHIN 60 NM S OF AXIS FROM 131W-135W.

NUMEROUS STRONG CONVECTION WITHIN 150 NM OF 06N85W.  SCATTERED 
MODERATE ISOLATED STRONG CONVECTION WITHIN 90 NM E QUADRANT OF 
LOW PRES AT 04N78W. 

...DISCUSSION...
STRONG UPPER LEVEL CYCLONE OVER CENTRAL PLAINS HAS TROUGH DIG SW 
TO 08N117W.  AXIS BRINGS VERY DRY AIR MASS TO ITS WEST N OF 21N 
WITH MODERATE TO STRONG SUBSIDENCE DUE TO CONVERGING WIND.  
TROPICAL MOISTURE ADVECTED INTO BASIN BY ANTICYCLONIC FLOW JUST 
UPSTREAM FROM TROUGH AXIS S OF 21N W OF 127W.  

DOWNSTREAM FROM TROUGH...JET STREAM WITH 135 KT ROUNDING BASE OF 
CYCLONE...JUST OVER SE TEXAS COAST...ADVECT ABUNDANT AMOUNTS OF 
TROPICAL MOISTURE FROM ITCZ CONVECTIVE DEBRIS AND MAKES IT 
AVAILABLE TO COLD FRONT NOW ACROSS CENTRAL TEXAS TO PROMPT MORE 
PRECIPITATION.  SWATH OF MOISTURE TRAPPED BETWEEN UPPER TROUGH 
AXIS AND PERIPHERY ALONG NORTHWESTERN QUADRANT OF ANTICYCLONIC 
GYRE CENTERED OVER GUATEMALA.  WHILE SUBSIDING AIR HELPS KEEP 
DRY AIR MASS UNDER GYRE...REGION OF UPPER LEVEL DIFFLUENCE 
BETWEEN ANTICYCLONE AND WEAK DOWNSTREAM UPPER LEVEL TROUGH OVER 
COSTA RICA PROMOTED LARGE AREA OF NUMEROUS DEEP CONVECTION 
WITHIN 150 NM OF 06N85W.  SOME CYCLONIC ORGANIZATION WAS NOTED 
EARLIER AT THE SURFACE...BUT HAS BEEN LOST SINCE...AND MODEL 
GUIDANCE FOCUSES INTO AREA FOR DEVELOPMENT OF LOW PRES CENTER.  
NEXT DISCUSSION MIGHT SHED MORE IN THIS RESPECT AS SATELLITE 
VISIBLE IMAGES PROVIDE BETTER INSIGHT THAN IR.  STRONG SW WINDS 
NOTED COMING INTO SE CORNER OF BASIN...POSSIBLY DUE TO LOW PRES 
FORMATION...AND CROSS EQUATORIAL SWELL MOVE N INTO E PAC W OF 
100W.  ON THE OTHER HAND...AS ANTICYCLONIC GYRE MOVES E TO MERGE 
WITH SOUTH AMERICAN RIDGE DIFFLUENT AREA ALOFT WOULD DISAPPEAR 
AND LESS FAVORABLE CONDITIONS WOULD CURTAIL DEEP CONVECTION NOW 
PRESENT.  

ELSEWHERE AT THE SURFACE...
HEALTHY BROAD HIGH PRES CENTER 1032 MB AT 36N138W MOVES NE AND 
WEAKENS ALLOWING FRESH NE TRADES TO DIMINISH SUN AND MON.  WEAK 
SURFACE TROUGH ALONG 125W HAS MOVED AWAY FROM FAVORABLE UPPER 
LEVEL ENVIRONMENT AND LOST MOST OF ITS DEEP CONVECTION.

    
 


$$
WALLY BARNES