MESOSCALE PRECIPITATION DISCUSSION 0431
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
121 PM EDT THU JUL 07 2016
 
AREAS AFFECTED...FAR SOUTHEAST IL...WESTERN/SOUTHERN KY...NORTHERN
TN 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 071720Z - 072130Z
 
SUMMARY...AN APPROACHING LINE OF THUNDERSTORMS WILL PRODUCE HEAVY
RAINS OVER SATURATED SOILS THIS AFTERNOON. IN THE WAKE OF LAST
NIGHTS HEAVY RAIN...THIS ADDITIONAL RAINFALL MAY CAUSE MORE FLASH
FLOODING/RUNOFF PROBLEMS.

DISCUSSION...THERE IS A PROGRESSIVE LINE OF THUNDERSTORMS
EXTENDING FROM SOUTH-CENTRAL IL DOWN INTO SOUTHEAST MOVING DOWN TO
THE EAST-SOUTHEAST. THIS LINE OF CONVECTION IS ASSOCIATED WITH A
SHORTWAVE TROUGH CURRENTLY ADVANCING EAST ACROSS THE MIDWEST.
GIVEN STRONG SOLAR INSOLATION AND RESULTING DIABATIC
HEATING...MLCAPE VALUES HAVE RECOVERED TO OVER 3000 J/KG FROM
SOUTHEAST MO INTO SOUTHEAST IL AND INTO WESTERN KY AND NORTHWEST
TN. 

THE THERMODYNAMIC ENVIRONMENT AHEAD OF THIS LINE IS THEREFORE
QUITE SUPPORTIVE OF CONVECTIVE SUSTAINABILITY AND WITH SOME
GRADUAL INTENSIFICATION OVER THE NEXT COUPLE OF HOURS ANTICIPATED
GIVEN ADDITIONAL SOLAR INSOLATION AND INSTABILITY RECOVERY. EXPECT
THE LINE OF CONVECTION TO MOVE THROUGH SOUTHEAST IL AND INTO
WESTERN/SOUTHERN KY AND GRADUALLY NORTHERN TN THROUGH THE
MID-AFTERNOON HOURS BASED ON THE WEST-NORTHWEST STEERING FLOW
THROUGH THE COLUMN.

PWATS AS PER BLENDED-TPW AND GPS DATA ARE ON THE ORDER OF 1.8 TO
2.0 INCHES ACROSS THE THREAT AREA...AND SO RAINFALL RATES WILL
AGAIN BE ENHANCED DUE TO THE EFFICIENT RAINFALL PROCESSES. THE
MITIGATING FACTOR WITH THIS NEXT ROUND OF CONVECTION WILL BE THE
PROGRESSIVE NATURE OF IT...BUT FFG VALUES ARE VERY LOW ACROSS THE
REGION IN THE WAKE OF LAST NIGHTS RAINFALL WHICH WAS AS MUCH AS 6
TO 10 INCHES OVER FAR WESTERN KY AND PARTS OF NORTHERN TN. 

ANY ADDITIONAL RAINFALL ON THESE SATURATED GROUNDS WILL RISK
ADDITIONAL FLASH FLOODING. ONE HOUR RAINFALL TOTALS WITH THIS NEXT
LINE OVER SOUTHEAST MO HAVE BEEN CLOSE TO 1 INCH...AND THESE
AMOUNTS WILL POSSIBLY BE JUST ENOUGH TO TRIGGER ADDITIONAL FLASH
FLOODING THIS AFTERNOON AS THE LINE MOVES THROUGH. WILL CONTINUE
TO MONITOR.

ORRISON

ATTN...WFO...JKL...LMK...MEG...MRX...OHX...PAH...

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

LAT...LON   37708797 37698746 37618682 37588621 37538537 
            37488396 37108362 36638392 36198505 36048588 
            36078695 36228766 36428832 36548861 36908903 
            37328903 37688856