MESOSCALE PRECIPITATION DISCUSSION 0081...CORRECTION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1109 AM EDT THU MAY 29 2014
 
CORRECTED FOR TYPOS IN BOTH PARAGRAPHS

AREAS AFFECTED...SOUTH-CENTRAL LA AND SOUTHWEST MS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 291433Z - 291733Z
 
SUMMARY...A NARROW BAND OF THUNDERSTORMS IS DEVELOPING ACROSS
SOUTH-CENTRAL LA AND SHOWING NO MOVEMENT.  REGIONAL FLASH FLOODING
IS POSSIBLE OVER THE NEXT FEW HOURS.

DISCUSSION...THE INTERSECTION OF A SURFACE TROUGH/BAROCLINIC
TROUGH AND AN OUTFLOW BOUNDARY IS HELPING TO FOCUS A NEW LINE OF
THUNDERSTORMS NEAR THE ATCHAFALAYA RIVER BASIN.  THE THUNDERSTORMS
HAVE SHOWN LITTLE SIGN OF MOVEMENT AS THEY TRAIN ALONG A NARROW
BAND.  THE MOST RECENT MESOSCALE GUIDANCE SHOWS A MODERATE SIGNAL
FOR HEAVY RAINFALL IN THIS AREA.  THE 0-3 KM WIND SHEAR IS NEAR 25
KTS AND CAPE VALUES ARE CLOSE TO 1000 J/KG, NEAR THE LOWER
THRESHOLD FOR THE WET MULTI-CELL ENVIRONMENT.  PRECIPITABLE WATER
VALUES ARE SUFFICIENT FOR POTENTIALLY HEAVY RAINFALL, SITTING NEAR
1.75", WHICH IS ABOVE THE 90TH PERCENTILE FOR LATE MAY.

OVER THE NEXT FEW HOURS, A SURFACE COLD POOL IS EXPECTED TO
DEVELOP NEAR THE NARROW BAND WHICH SHOULD MOVE THE THUNDERSTORMS
SLOWLY EAST AND SOUTHEASTWARD PER 06Z GFS CORFIDI VECTORS.  THE
00Z ARW FORECASTS THE MAXIMUM CAPE VALUES TO SHIFT NORTHEAST WITH
TIME, WHICH SHOULD ALLOW THE THUNDERSTORM BAND TO EXTEND NORTHEAST
AND WOULD OCCUR AS THE WESTERN PORTION OF AN OUTFLOW BOUNDARY
ACROSS SOUTHERN LA RETURNS NORTHEAST (AS THERE IS NO CONVECTION IN
SOUTHEAST LA TO MAINTAIN THE BOUNDARY'S CURRENT LOCATION). 
RAINFALL RATES NEAR 2" AN HOUR IN STRONGER CELLS COULD CAUSE
REGIONAL FLASH FLOODING.

ROTH

ATTN...WFO...JAN...LIX...LCH...

ATTN...RFC...LMRFC...

LAT...LON   29679266 30389241 31619168 31769122 31459113 30839136
            29999174 29519218 29519254 29679266