MESOSCALE PRECIPITATION DISCUSSION 0269
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1134 AM EDT THU JUN 07 2018

AREAS AFFECTED...OK

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 071530Z - 071930Z

SUMMARY...SLOW-MOVING HEAVY SHOWERS AND THUNDERSTORMS WILL
CONTINUE TO PROMOTE A FLASH FLOOD THREAT OVER THE NEXT FEW HOURS.

DISCUSSION...THE LATEST RADAR IMAGERY SHOWS MULTIPLE CLUSTERS OF
HEAVY SHOWERS AND THUNDERSTORMS DROPPING S/SE ACROSS NORTHERN AND
CENTRAL OK WHICH ARE PRODUCING VERY HEAVY RAINFALL. SURFACE
OBSERVATIONS HAVE BEEN CONFIRMING 1 TO 2 INCH/HR RAINFALL RATES
WHICH IS BEING AIDED BY PWATS OF 1.5 TO 1.7 INCHES. THE CONVECTION
HAS BEEN ANCHORING ALONG A NNW/SSE INSTABILITY GRADIENT IN AN
ELEVATED FASHION...WITH MUCAPE VALUES OF 2000 TO 2500 J/KG NOTED
ACROSS CENTRAL OK...AND THE ACTIVITY FOCUSED ALONG THE EASTERN
SIDE OF THIS GRADIENT.

CLOUD TOP TEMPS AS SEEN IN GOES-16 CLEAN IR IMAGERY HAVE ACTUALLY
BEEN COOLING OVER THE LAST HOUR OVER NORTH-CENTRAL OK...AND THIS
COUPLED WITH GOES-16 DAY CONVECTION RGB IMAGERY SUGGEST AN
INCREASE IN STRONG CONVECTIVE UPDRAFTS/FORCING FOR ENHANCED
RAINFALL RATES. THE GLD-360 LIGHTNING DENSITY DATA OVER THE LAST
HOUR HAS BEEN SHOWING VIGOROUS STRIKE ACTIVITY AND IS CORRELATING
NICELY TO THE WELL ORGANIZED STATE OF THE CONVECTION.

THE HRRR AND HRRRX GUIDANCE ARE A LITTLE SLOW WITH THE S/SE
ADVANCE OF THE CONVECTIVE MASS AT THIS TIME...BUT THE THINKING IS
THAT CONVECTION WILL CONTINUE TO DROP DOWN ACROSS AREAS OF CENTRAL
OK WITH SOME REPEATING CLUSTERS GIVEN THE ORIENTATION OF THE
INSTABILITY AXIS AND ALSO FOCUSED DEEP LAYER MOISTURE CONVERGENCE.

EXPECT AS MUCH AS AN ADDITIONAL 3 TO 4 INCHES OF RAIN LOCALLY OVER
THE NEXT FEW HOURS AND THIS WILL DRIVE ADDITIONAL POTENTIAL FOR
FLASH FLOODING. WILL CONTINUE TO MONITOR.

ORRISON

ATTN...WFO...OUN...TSA...

ATTN...RFC...ABRFC...

LAT...LON   36919747 36659691 36149660 35219621 34499619
            34229656 34269703 34699746 35979817 36739807