000
AXPZ20 KNHC 040938
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SAT APR 04 2009

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 
0800 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE LIES ALONG A LINE FROM 06N77W 
TO 05N83W TO 06N93W TO 02N120W TO 02N140W. NO SIGNIFICANT 
CONVECTION CAN BE FOUND NEAR THE ITCZ.

...DISCUSSION...
A WEAK AND NEARLY ZONAL MID TO UPPER LEVEL TROUGH STRETCHED 
FROM 29N115W TO 24N140W WILL BE REINFORCED BY THE MID LATITUDE 
ENERGY CUTTING OFF FROM THE NORTHERN STREAM WITH THE ASSOCIATED 
DEEP LAYER LOW CENTER CURRENTLY LYING NEAR 50N145W. THIS DEEP 
LAYER LOW WILL SLOWLY MOVE SOUTHEASTWARD THROUGH THE NE PACIFIC 
TOWARD CALIFORNIA OVER THE NEXT FEW DAYS.  AT THE SURFACE...THE 
ASSOCIATED COLD FRONT WILL PASS INTO NW WATERS EARLY SUN MORNING 
AND NW SWELL ON THE ORDER OF 15 TO 18 FT WILL MOVE IN BEHIND THE 
FRONT.  

THE APPROACHING FRONT WILL WEAKEN THE SURFACE RIDGE IN PLACE 
FROM 1026 MB LOW PRES NEAR 38N130W TO 30N128W TO 15N118W.  TRADE 
WINDS OVER W WATERS SW OF THE AXIS WILL DIMINISH AS THE RIDGE 
BREAKS DOWN.  MEANWHILE...THE 0142 AND 0322 UTC QUIKSCAT PASSES 
SHOWED 20 KT NORTHERLY WINDS OVER NE WATERS BETWEEN THE RIDGE 
AXIS AND LOW PRESSURE OVER THE SW CONUS.  THESE WINDS WILL ALSO 
DIMINISH OVER THE NEXT DAY OR TWO AS THE RIDGE WEAKENS AND THE 
LOW PRESSURE OVER THE SW CONUS SHIFTS EASTWARD.  IN 
ADDITION...THE 0142 UTC QUIKSCAT PASS REVEALED SOUTHERLY FLOW 
OVER THE NORTHERN GULF OF CALIFORNIA AHEAD OF THE SW CONUS 
TROUGHING.  WHILE THESE WINDS ARE EXPECTED TO DIMINISH BELOW 20 
KT THIS MORNING...WINDS WILL ONCE AGAIN BRIEFLY REACH 20 KT SUN 
AFTERNOON THROUGH MON MORNING AS THE SW CONUS COLD FRONT FINALLY 
WORKS ITS WAY SOUTHWARD INTO NW MEXICO/NORTHERN GULF OF 
CALIFORNIA.

SOUTH OF THE ZONAL TROUGH AXIS STRETCHED ACROSS N WATERS... MID 
TO UPPER LEVEL MOISTURE IS INDUCING MULTILAYERED CLOUDINESS 
WITHIN 360 NM OF A LINE FROM 25N107W TO 12N140W.  AN UPPER LEVEL 
TROUGH LIES SOUTH OF THIS REGION ALONG 115W.  VERTICAL LIFT 
ASSOCIATED WITH THE REAR RIGHT QUADRANT OF THE SOUTHERLY UPPER 
JET ON THE LEADING EDGE OF THIS TROUGH IS ACTING ON PLENTIFUL 
LOW LEVEL MOISTURE...WITH PRECIPITABLE WATER VALUES IN EXCESS 
OF 2 INCHES.  SATELLITE WATER VAPOR IMAGERY CONFIRMS THIS 
INCREASE IN MOISTURE IN THE MID TO UPPER LAYERS AND INDICATES 
SOME CYCLONIC ROTATION ALOFT CENTERED NEAR 02N117W NEAR THE 
ITCZ.  HOWEVER...THERE IS NO DEEP CONVECTION NOTED YET WITH THE 
SYSTEM.  

EAST OF THIS UPPER TROUGH...A STRONG ANTICYCLONE AND AN 
ASSOCIATED DRY AIR MASS CENTERED OVER SOUTHERN MEXICO ALLOWS 
SUBSIDENCE TO DOMINATE THE AREA S OF 20N. THIS RIDGE ENVELOPS SE 
MEXICO AND NORTHERN CENTRAL AMERICA WHERE MOSTLY FAIR WEATHER 
PREVAILS.

$$
SCHAUER CLARK