000
AXPZ20 KNHC 030350
TWDEP 

TROPICAL WEATHER DISCUSSION                                   
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
0405 UTC WED APR 03 2013

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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0130 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...              
THE MONSOON TROUGH AXIS WAS ANALYZED FROM 08N78W TO 09N85W TO 
04N92W TO 04N100W. THE ITCZ AXIS WAS ANALYZED FROM 04N100W TO 
05N113W TO 03N123W TO A TROUGH FROM 09N140W TO 02N138W. 
SCATTERED MODERATE TO STRONG CONVECTION WAS N OF 03N TO THE AXIS 
BETWEEN 85W AND 92W. SCATTERED MODERATE CONVECTION WAS N OF 03N 
TO THE AXIS BETWEEN 80W AND 85W AS WELL AS N OF THE AXIS TO 09N 
BETWEEN 130W AND 138W. 

...DISCUSSION...                                               
SCATTERED MODERATE TO STRONG CONVECTION S OF THE MONSOON TROUGH 
FOUND SW OF COSTA RICA IS DESCRIBED IN THE SECTION ABOVE. 
PRECIPITABLE WATER IMAGERY SHOWS VALUES IN THE REGION ARE 
HIGH...IN THE 2.0-2.5 INCH RANGE. VERTICAL LIFT HERE IS BEING 
ENHANCED BY UPPER DIFFLUENCE ON THE W SIDE OF A WEAK ANTICYCLONE 
NEAR 06N80W. THIS ANTICYCLONE IS FORECAST TO WEAKEN AND MERGE 
WITH AN ANTICYCLONE TO ITS SE...KEEPING AN UPPER RIDGE AXIS OVER 
E WATERS NEAR THE MONSOON TROUGH THAT WILL ENHANCE CONVECTION 
INTO THU.

ELSEWHERE...THE UPPER PATTERN CURRENTLY FEATURES A LONG-WAVE 
TROUGH ALONG 107W WITH WEAK RIDGING TO ITS E AND A MORE 
AMPLIFIED RIDGE TO ITS W. AN UPPER LOW LIES NW OF THE FORECAST 
AREA NEAR 39N146W. AN UPPER JET ON THE SE SIDE OF THE LOW MEETS 
UP WITH THE SOUTHERN STREAM UPPER JET OVER WESTERN WATERS N OF 
10N. THIS MERGED JET IS TRANSPORTING TROPICAL MOISTURE INTO THE 
FORECAST AREA. MULTI-LEVELED CLOUDS AND SCATTERED SHOWERS WITH 
POSSIBLY SOME ISOLATED THUNDERSTORMS LIE IN THE AREA N OF 14N W 
OF 130W. THE PATTERN IS PROGRESSIVE. THE UPPER LOW IS DRAGGING A 
TROUGH INTO NW WATERS THAT WILL TURN NEGATIVE TILT AND LIE FROM 
31N132W TO 26N129W WED EVENING. MEANWHILE...THE LONG-WAVE TROUGH 
WILL MOVE EASTWARD ACROSS MEXICO AND STRETCH ALONG 99W N OF 08N 
IN THE PACIFIC BY THU EVENING.

THE 1024 MB SUBTROPICAL SURFACE HIGH LIES NEAR 32N127W AND 
EXTENDS A RIDGE SOUTHEASTWARD TO 25N120W. A COLD FRONT 
ASSOCIATED WITH THE AFOREMENTIONED UPPER LOW WAS ANALYZED FROM 
32N137W TO 28N140W. THE WEAKENED COLD FRONT WILL MOVE TO 32N130W 
TO 24N135W BY WED EVENING BEFORE DISSIPATING WED NIGHT. THE 
SUBTROPICAL HIGH WILL WEAKEN WED AND MERGE WITH HIGH PRES BEHIND 
THE COLD FRONT...REORIENTING THE RIDGE AXIS SOUTHWARD ALONG 25N 
W OF 125W BY LATE THU.
 
ON THE W SIDE OF THE SUBTROPICAL RIDGE...FRESH TO STRONG TRADE 
WINDS ARE CONFINED TO WITHIN 90 NM OF A SURFACE TROUGH FROM 
09N140W TO 02N138W OVER W WATERS. AS THE SUBTROPICAL HIGH AND 
THE TROUGH WEAKEN OVERNIGHT...THE AREA OF FRESH TO STRONG TRADES 
WILL DISSIPATE. TO THE E OF THE RIDGE...FRESH TO STRONG NW WINDS 
CONTINUE WITHIN 120 NM W OF THE BAJA CALIFORNIA PENINSULA N OF 
25N. THESE WINDS ARE FORECAST TO DIMINISH AND SEAS WILL SUBSIDE  
THROUGH WED MORNING AS THE SUBTROPICAL HIGH WEAKENS. 

$$
SCHAUER