MESOSCALE PRECIPITATION DISCUSSION 0054
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
500 PM EDT MON MAY 20 2013
 
AREAS AFFECTED...CENTREAL AND NORTHEAST OK...SOUTHEAST
KS...WESTERN MO 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 202100Z - 210100Z
 
SUMMARY...GRADUALLY INCREASING THREAT FOR TRAINING CONVECTION THE
NEXT FEW HOURS...AND THEREFORE SOME POTENTIAL FOR FLASH FLOODING.

DISCUSSION...A BAND OF SEVERE THUNDERSTORMS HAS DEVELOPED ALONG
AND JUST AHEAD OF A SW/NE ORIENTED FRONTAL ZONE INVOLVING PORTIONS
OF EXTREME NERN OK...SERN KS AND FAR WESTERN MO. STRONG DIURNAL
HEATING HAS RESULTED IN SFC-BASED CAPE VALUES LOCALLY EXCEEDING
4000 J/KG...WHICH HAS BEEN MORE THAN ENOUGH OVER THE LAST 1 TO 2
HOURS TO BREAK THROUGH THE CAP FOCUSED AROUND 800 MB AND INITIATE
CONVECTION AS PER 18Z KOUN RAOB. GLATEST GOES-SOUNDER CAPE VALUES
CONFIRM THIS DEGREE OF STRONG INSTABILITY AS WELL.

THE CONCERN OVER THE NEXT FEW HOURS WILL BE DEEP LAYER SWLY FLOW
PARALLELING THE FRONTAL ZONE...AND SUPPORTING A LINEARLY ORIENTED
CONVECTIVE AXIS THAT WILL BE CONDUCIVE TO TRAINING CONVECTIVE
CELLS. WHILE THE STORM MODE ATTM IS OVERWHELMINGLY SEVERE...EXPECT
THERE TO BE A GRADUAL INCREASE IN THE THREAT FOR FLASH FLOODING
THE NEXT FEW HOURS AS ADDITIONAL UPSTREAM CONVECTIVE DEVELOPMENT
TAKES PLACE AND ATTEMPTS TO TRAIN OVER THE SAME AREA. GOES-SOUNDER
PWATS OF 1.3 TO 1.4 INCHES WILL BE CONDUCIVE TO PRODUCING RAINFALL
RATES OF UP TO 1.5 INCHES/HR. WILL CONTINUE TO MONITOR.

ORRISON


ATTN...WFO...SGF...EAX...TSA...TOP...ICT...OUN...

LAT...LON   38929336 37329440 36229539 35449608 34789695 34539767
            34779824 35349803 36119724 37489572 39249448 39849347
            38929336