MESOSCALE PRECIPITATION DISCUSSION 0232
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
530 AM EDT FRI MAY 19 2017

AREAS AFFECTED...CENTRAL ILLINOIS

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

VALID 190929Z - 191329Z

SUMMARY...A FLASH FLOOD THREAT WILL CONTINUE INTO EARLY THIS
MORNING OVER CENTRAL ILLINOIS.

DISCUSSION...ELEVATED CONVECTION CONTINUES TO BACKBUILD INTO AND
NORTH OF A STATIONARY FRONT EXTENDING FROM WEST TO EAST ACROSS
ILLINOIS INTO INDIANA. SOUTHERLY FLOW INTO AND OVER THIS BOUNDARY
IS LIKELY BEING ENHANCED AHEAD OF THE CONVECTIVELY ENHANCED LOW
OVER MISSOURI. MOST GUIDANCE HAS BEEN UNDER DOING THE AREAL EXTENT
AND INTENSITY OF THIS CONVECTION...PROBABLY IN PART BECAUSE OF
UNDER DOING LOW LEVEL MOISTURE TRANSPORT AHEAD OF THE MCV OVER
MISSOURI.

MODELS WANT TO PUSH THE BOUNDARY NORTH WITH TIME...ALTHOUGH
OUTFLOW IS CURRENTLY HELPING REINFORCE ITS STATIONARY POSITION. SO
WHILE SOME NORTHWARD PUSH IS PROBABLE OVER THE NEXT FEW HOURS...DO
NOT ANTICIPATE MUCH MOVEMENT. THUS THOSE AREAS THAT HAVE BEEN
SEEING REPEAT CONVECTION MAY CONTINUE TO FOR THE NEXT FEW HOURS.
RECENT IR IMAGERY HAS INDICATED WARMING CLOUD TOPS OVER CENTRAL
IL...LIKELY INDICATIVE OF A DECREASE IN CONVECTIVE INTENSITY AND
THUS RAINFALL RATES. HOWEVER WOULD EXPECT TO STILL SEE ELEVATED
CONVECTION (ALBEIT A BIT WEAKER) CONTINUE UNTIL THE CONVECTIVE
LINE PASSES THROUGH. EVEN THOUGH IT SHOULD BE PROGRESSIVE...THE
APPROACHING CONVECTIVE LINE WILL ALSO RESULT IN A PERIOD OF
INTENSE RAINFALL RATES. BOTH OF THESE FACTORS WILL CONTINUE TO
EXACERBATE ANY ONGOING FLOODING...AND POTENTIALLY CAUSE AT LEAST
ISOLATED ADDITIONAL FLASH FLOOD CONCERNS.

CHENARD

ATTN...WFO...ILX...LSX...

ATTN...RFC...NCRFC...OHRFC...

LAT...LON   40428761 39898755 39598805 39388970 39339023
            39389097 39699142 40029146 40089066 40238901