MESOSCALE PRECIPITATION DISCUSSION 0039
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
753 PM EDT THU MAY 16 2013
 
AREAS AFFECTED...ARKLATEX INTO SRN/CNTRL ARKANSAS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 162351Z - 170551Z
 
SUMMARY...TRAINING CONVECTION NORTH OF AN OUTFLOW BOUNDARY ACROSS
NRN TEXAS/LOUISIANA MAY CAUSE LOCALIZED FLASH FLOODING.

DISCUSSION...23Z MESOANALYSIS PLACED AN OUTFLOW BOUNDARY FROM DTO
TO GGG TO JUST SOUTH OF SHV WHILE RECENT RADAR IMAGERY HAS SHOWN A
COUPLE OF NARROW BANDS OF TRAINING CONVECTION ACROSS SWRN
ARKANSAS. CELLS ARE DEVELOPING DUE TO LOW LEVEL WARM ADVECTION
ATOP THE RAIN COOLED AIRMASS INTO A VERY MOIST BUT ONLY MARGINALLY
UNSTABLE ENVIRONMENT IN PLACE FROM THE ARKLATEX INTO SRN/CENTRAL
LOUISIANA. RECENT GPS PWS INDICATE AN INCREASING TREND OF DEEP
MOISTURE AT SHV...WITH PW VALUES OF 1.65" AT 22Z.

WATER VAPOR IMAGERY AT 23Z INDICATED AN UPPER LOW TRACKING
NORTHEASTWARD ACROSS NRN ARKANSAS WHICH SHOULD HAVE THE EFFECT OF
SLOWLY VEERING LOW LEVEL FLOW TOWARD THE SOUTHWEST AND
WEST-SOUTHWEST EARLY TONIGHT...WHICH SHOULD CONTINUE TO OVERRUN
THE OUTFLOW BOUNDARY. RAINFALL RATES OF 1 TO 2 IN/HR WILL BE
POSSIBLE THROUGH AT LEAST 03Z AS SUGGESTED BY RECENT RUNS OF THE
HRRR AND HRW NMM/ARW HI-RES MODELS...CONFIRMED BY RECENT DUAL-POL
1 HR RAINFALL RATES ACROSS EXTREME SRN ARKANSAS. AS DRIER
MID-LEVEL AIR MOVES INTO THE THREAT AREA AFTER 03Z...THE
OVERRUNNING CONVECTION SHOULD COME TO AN END FROM WEST TO
EAST...BUT WILL CONTINUE TO MONITOR THE SITUATION.

OTTO


ATTN...WFO...MEG...JAN...LZK...SHV...TSA...

LAT...LON   34889192 34769096 34149070 32969131 32929417 33199493
            33859527 34469457 34649307 34889192