MESOSCALE PRECIPITATION DISCUSSION 0109
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
510 PM EDT MON JUN 17 2013
 
AREAS AFFECTED...EAST-CENTRAL MO...SOUTHERN IL 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 172110Z - 172300Z
 
SUMMARY...A BAND OF THUNDERSTORMS HAS DEVELOPED AND REMAINED
QUASI-STATIONARY FROM ST. LOUIS MO EASTWARD ACROSS SOUTH-CENTRAL
IL OVER THE PAST HOUR OR SO.  SINCE THE LINE COULD PERSIST FOR
ANOTHER HOUR OR TWO, BELIEVE FLASH FLOODING IS POSSIBLE IN THIS
AREA.

DISCUSSION...A SURFACE BOUNDARY/FRONT COMBINED WITH DAYTIME
HEATING, AVAILABLE PRECIPITABLE WATER VALUES OF 1.75-2 INCHES, AND
DIVERGENCE ALOFT FROM A SHORTWAVE IN SOUTHWEST MO HAS FORCED A
CONVECTIVE LINE TO FORM FROM ST. LOUIS EASTWARD ACROSS
SOUTH-CENTRAL IL.  THE 18Z HRRR HAS SOME IDEA OF THIS DEVELOPMENT
AND EXPECTS THE HEAVIER ACTIVITY TO MOVE FROM WEST TO EAST ALONG
THE LINE'S AXIS WITH TIME.  AS 850 HPA INFLOW IS RATHER WEAK,
THINK THE LINE'S FUTURE WILL BE A SHORT ONE.  EVEN SO, HEAVY
RAINFALL OVER A COUPLE HOURS COULD EXCEED THE FLASH FLOOD GUIDANCE
IN THE AREA OF TWO INCHES IN THREE HOURS.  A REPORT FROM ST. LOUIS
HAS INDICATED THAT TWO INCHES OF RAINFALL HAS ALREADY FALLEN
WITHIN THEIR METROPOLITAN AREA FROM THIS RAIN BAND.  LOCAL
RAINFALL AMOUNTS OF 2-4 INCHES ARE POSSIBLE IN THIS REGION BEFORE
23Z/6 PM CDT, WHICH COULD LEAD TO FLASH FLOODING.

ROTH

ATTN...WFO...IND...PAH...ILX...LSX...

ATTN...RFC...LMRFC...MBRFC...NCRFC...OHRFC...

LAT...LON   38958753 39118836 39078984 38849069 38319054 38028924
            38258782 38958753