000
AXPZ20 KNHC 192151
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC MON APR 19 2010

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 06N77W TO 06N105W TO 08N115W TO 05N140W.  SCATTERED 
MODERATE CONVECTION WITHIN 240 NM S OF AXIS E OF 83W.  SCATTERED 
MODERATE CONVECTION WITHIN 150 NM S OF AXIS FROM 107W-115W.  

...DISCUSSION...
UPPER LEVEL TROUGH ENTERS BASIN FROM 32N138W TO 25N140W WITH 
VERY DRY AIR MASS N OF 21N W OF 127W DUE TO MODERATE TO STRONG 
SUBSIDENCE.  DOWNSTREAM BROAD RIDGE CENTERED AT 07N110W 
MONOPOLIZES CENTRAL PORTION OF E PAC TRAPPING SWATH OF ABUNDANT 
TROPICAL MOISTURE BROUGHT INTO BASIN ON WEAK 50 KT JET CORE JUST 
S OF TROUGH BASE. QUICKLY WEAKENING UPPER LEVEL SHORT WAVE 
TROUGH OVER FOUR CORNERS REGION FLATTENS RIDGE CREST AND PROMPTS 
MODERATE TO STRONG DIFFLUENT PATTERN ALOFT ENHANCING HEALTHY 
CONVECTION OVER NORTHERN MEXICO AND W TEXAS N OF 28N.  TROPICAL 
MOISTURE SOURCE HAS DECOUPLED FROM SHORT WAVE TROUGH SO 
CONVECTION EXPECTED TO DIMINISH WITHIN 24 HRS.  FURTHER 
DOWNSTREAM...UPPER LEVEL LONGWAVE TROUGH EXTEND FROM NE GULF OF 
MEXICO ACROSS HONDURAS INTO E PAC THEN TO NOT-WELL-DEFINED 
CYCLONE AT 02N92W.  TROUGH KEEPS AIR MASS FAIRLY DRY WITH MINOR 
SCATTERED MODWERATE CONVECTION S OF ITCZ E OF 83W. 

AT THE SURFACE...
WEAK COLD FRONT EXTEND INTO E PAC FROM 32N131W TO 27N140W WITH 
HEALTHY 1027 MB HIGH PRES BEHIND IT.  RIDGE REBUILDS OVER BASIN 
FROM THE NW ON TUE BRINGING BACK FRESH TRADES W OF 125W  
INCREASING TO STRONG BY END OF FORECAST PERIOD.  FRESH NW BREEZE 
PICKS UP ALONG BAJA CALIFORNIA COAST N OF 25N AS HIGH PRES DRIFT 
E.  VERY LONG NW-SE FETCH ON RIDGE PERIPHERY BUILD LARGE LONG 
PERIOD NW SWELL ENTERING CORNER OF BASIN TONIGHT AND SPREAD AS 
FAR S AS 06N W OF 120W BY END OF FORECAST PERIOD.   

$$
WALLY BARNES