000
AXPZ20 KNHC 022109
TWDEP 

TROPICAL WEATHER DISCUSSION                                   
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
2205 UTC TUE APR 02 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1930 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...              
THE MONSOON TROUGH AXIS WAS ANALYZED FROM 09N78W TO 07N84W TO 
03N94W TO 03N100W. THE ITCZ AXIS WAS ANALYZED FROM 03N100W TO 
05N105W TO 05N117W TO 03N125W TO 05N136W TO A TROUGH ALONG 138W 
FROM 03N TO 08N. SCATTERED MODERATE TO STRONG CONVECTION WAS 
WITHIN 90 NM N AND 270 NM S OF THE AXIS BETWEEN 80W AND 86W AND 
WITHIN 60 NM EITHER SIDE OF THE AXIS BETWEEN 87W AND 90W. 
SCATTERED MODERATE CONVECTION WAS WITHIN 330 NM S OF THE AXIS E 
OF 80W AS WELL AS WITHIN 210 NM N AND 60 NM S OF THE AXIS 
BETWEEN 125W AND 138W.

...DISCUSSION...                                               
SCATTERED MODERATE TO STRONG CONVECTION ON THE EASTERN SIDE OF 
THE ITCZ S OF COSTA RICA AND PANAMA 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 05N80W. 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 109W WITH WEAK RIDGING TO ITS E AND A MORE 
AMPLIFIED RIDGE TO ITS W. AN UPPER LOW LIES NW OF THE FORECAST 
AREA NEAR 38N147W. 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 LIE IN 
THE AREA N OF 15N W OF 130W. THE PATTERN IS PROGRESSIVE. THE 
UPPER LOW WILL DRAG A TROUGH INTO NW WATERS BY WED AND LIE FROM 
31N125W TO 20N139W. MEANWHILE...THE LONG-WAVE TROUGH WILL MOVE 
EASTWARD ACROSS MEXICO AND STRETCH ALONG 100W N OF 08N IN THE 
PACIFIC BY THU AFTERNOON.

THE 1024 MB SUBTROPICAL SURFACE HIGH LIES NEAR 31N125W AND 
EXTENDS A RIDGE SOUTHEASTWARD TO 24N120W. A COLD FRONT 
ASSOCIATED WITH THE AFOREMENTIONED UPPER LOW IS CURRENTLY 
APPROACHING NW FORECAST WATERS. THE WEAKENED COLD FRONT WILL 
MOVE TO 32N134W TO 21N140W BY WED AFTERNOON AND MOVE NE AS IT 
DISSIPATES THROUGH THU MORNING. 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 THU EVENING.
 
ON THE W SIDE OF THE SUBTROPICAL RIDGE...FRESH TO STRONG TRADE 
WINDS ARE CONFINED FROM 10N-16N BETWEEN 125W-133W ACCORDING TO 
THE LATEST ASCAT PASSES. AS THE SUBTROPICAL HIGH AND THE PRES 
GRADIENT BETWEEN THE HIGH AND THE ITCZ WEAKENS THROUGH WED...THE 
AREA OF FRESH TO STRONG TRADES WILL SHRINK AND FINALLY DISSIPATE 
WED NIGHT. TO THE E OF THE RIDGE...FRESH TO STRONG NW WINDS 
CONTINUE WITHIN 120 NM W OF THE BAJA CALIFORNIA PENINSULA N OF 
28N. THESE WINDS ARE FORECAST TO DIMINISH AND SEAS WILL SUBSIDE  
THROUGH WED MORNING AS THE SUBTROPICAL HIGH WEAKENS. 

$$
SCHAUER