000
AXPZ20 KNHC 030929
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI APR 03 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 
0730 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE LIES ALONG A LINE FROM 08N82W 
TO 03N100W TO 06N127W TO 04N140W. ISOLATED MODERATE CONVECTION 
CAN BE FOUND WITHIN 75 NM N OF AXIS FROM 85W TO 90W AND WITHIN 
45 NM N OF AXIS FROM 110W TO 115W. SCATTERED MODERATE CONVECTION 
LIES WITHIN 30 NM N OF AXIS W OF 139W.

...DISCUSSION...

AT THE SURFACE...A 1033 MB HIGH CENTERED NW OF DISCUSSION AREA 
NEAR 37N149W EXTENDS A RIDGE THROUGH THE REGION FROM 30N140W TO 
15N115W. THE PRES GRADIENT BETWEEN THE RIDGE AND THE ITCZ HAS 
THE WINDS UP TO 20 KT N OF THE ITCZ WEST OF 130W...AND ALSO IN 
THE 20 TO 25 KT RANGE N OF 28N BETWEEN 119W AND 125W AS THE 
RIDGE INTERACTS WITH LOWER PRES OVER THE SW CONUS. THE TRADE 
WINDS ARE EXPECTED TO DIMINISH IN ABOUT 24 HOURS AS THE HIGH 
MOVES SOUTHEASTWARD AND WEAKENS. NORTH TO NORTHWESTERLY SWELL 
WILL CONTINUE TO PUSH INTO THE WATERS OFF THE NORTHERN BAJA 
PENINSULA THROUGH THE NEXT 36 HOURS...RANGING FROM 8 TO 12 FT. 

THE WEAK UPPER TROUGH STRETCHED OVER N WATERS FROM 30N120W TO 
27N140W WILL BE REINFORCED BY MID LATITUDE ENERGY CURRENTLY OVER 
THE N CENTRAL PACIFIC AS IT CUTS OFF FROM THE NORTHERN STREAM 
AND SENDS A DEEP LAYER LOW SOUTHEASTWARD THROUGH THE NE PACIFIC 
TOWARD CALIFORNIA.  AT THE SURFACE...THE COLD FRONT ASSOCIATED 
WITH THIS DEEP LAYER LOW WILL MOVE INTO NW WATERS EARLY SUN 
MORNING AND NW SWELL ON THE ORDER OF 15 FT WILL MOVE IN BEHIND 
THE FRONT.  

THE SUBTROPICAL JET ON THE LEADING EDGE OF THIS WEAK...NEARLY 
ZONAL TROUGH IS PUMPING MID TO UPPER LEVEL MOISTURE 
EAST-NORTHEASTWARD FROM 10N TO 25N MAINLY W OF 120W...MAKING FOR 
HIGH CLOUDINESS BUT LITTLE IN THE WAY OF SIGNIFICANT 
CONVECTION.  MEANWHILE THE MERIDIONAL UPPER TROUGH ALONG 120W S 
OF 15N IS PROVIDING SOME LIFT TO THE LOW LEVEL MOISTURE...WITH 
PRECIPITABLE WATER VALUES AROUND 1.5O INCHES...MAINLY S OF 12N. 
ISOLATED MODERATE CONVECTION CAN BE FOUND WITHIN 45 NM OF THE 
ITCZ AXIS FROM 110W TO 115W IN A REGION OF UPPER LEVEL SPEED 
DIFFLUENCE ON THE REAR RIGHT QUADRANT OF THE SUBTROPICAL JET.  
MEANWHILE...LIFT IN THE LEFT FRONT QUADRANT OF A JET MAX W OF 
THE MERIDIONAL UPPER TROUGH IS SUPPORTING SCATTERED MODERATE 
CONVECTION WITHIN 30 NM OF THE ITCZ AXIS W OF 139W...WITH BROAD 
UPPER LEVEL DIFFLUENCE FOUND HERE ALONG THE AXIS OF THE UPPER 
LEVEL ANTICYCLONE CENTERED W OF THE AREA NEAR 05S152W.  ANOTHER 
STRONG UPPER LEVEL ANTICYCLONE CAN BE FOUND NEAR 15N100W. 
SUBSIDENCE AND THE ASSOCIATED DRY AIR MASS IS NOTED IN MUCH OF 
THE REGION S OF 20N EAST OF 115W. THIS RIDGE ENVELOPS SE MEXICO 
AND NORTHERN CENTRAL AMERICA WHERE MOSTLY FAIR WEATHER 
PREVAILS...BUT TO ITS S...SOME ISOLATED MODERATE CONVECTION CAN 
BE FOUND 75 NM N OF THE ITCZ AXIS FROM 85W TO 90W NEAR THE 
REGION OF BROAD UPPER LEVEL DIFFLUENCE ON THE SOUTH SIDE OF THE 
ANTICYCLONE.   

$$
SCHAUER CLARK