MESOSCALE PRECIPITATION DISCUSSION 0271
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
749 PM EDT THU JUN 25 2015
 
AREAS AFFECTED...NRN MISSOURI INTO S-CNTRL ILLINOIS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 252348Z - 260548Z
 
SUMMARY...AN AXIS OF TRAINING CONVECTIVE RAINS WITH RATES
APPROACHING 2 IN/HR ARE EXPECTED TO SET UP FROM NRN MISSOURI INTO
SRN ILLINOIS. FLASH FLOODING IS CONSIDERED LIKELY...ESPECIALLY
GIVEN ABOVE AVERAGE RAINFALL ACROSS THE REGION OVER THE PAST
SEVERAL DAYS.

DISCUSSION...LATEST TRENDS IN RADAR IMAGERY SUPPORTED AN EXPANDING
AREA OF CONVECTION NEAR A STATIONARY FRONT EXTENDING THROUGH NRN
MISSOURI INTO S-CNTRL ILLINOIS ALONG WITH CONVECTION SOUTH OF THIS
FRONT NEAR A REMNANT OUTFLOW BOUNDARY. SURFACE DEWPOINTS IN THE
MID TO UPPER 70S IN PLACE OVER CNTRL MISSOURI HAVE ALLOWED FOR AN
INSTABILITY MAXIMUM ESTIMATED TO BE NEAR 4500 J/KG WITH AS HIGH AS
3000 K/KG JUST SOUTH OF THE STATIONARY FRONT...PER SPC
MESOANALYSIS PAGE. A RIBBON OF HIGHER PRECIPITABLE WATER
VALUES...NEAR 1.75 INCHES...WAS OBSERVED TO EXTEND ALONG THE FRONT
ACROSS THE MID-MISSISSIPPI RIVER VALLEY AND GOOD LOW LEVEL
CONVERGENCE WAS IN PLACE AT THE SURFACE. 

AS A BROAD NRN STREAM SHORTWAVE CONTINUES TO APPROACH FROM THE
CNTRL PLAINS...ASSOCIATED LIFT SHOULD TAP INTO THE LARGE RESERVOIR
OF INSTABILITY PRESENT OVER CNTRL/NRN MISSOURI INTO
ILLINOIS...WITH GENERALLY UNIDIRECTIONAL WLY FLOW ALOFT SUPPORTING
REPEATING CELL MOTIONS AND TRAINING OF HEAVY RAINFALL. GIVEN THE
MOISTURE IN PLACE...RAINFALL RATES UP TO 2 IN/HR CAN BE EXPECTED
WITH ADDITIONAL RAINFALL BY 06Z POSSIBLY INTO THE 4-6 INCH RANGE. 

HI-RES MODELS SUPPORT THIS IDEA ALTHOUGH THEIR TIMING AND
PLACEMENT HAS NOT BEEN CONSISTENT WITH RECENT OBSERVATIONS.
HOWEVER...WHEN ADJUSTMENTS ARE MADE FOR TIMING/PLACEMENT FROM THE
HI-RES MODELS TO CURRENT OBSERVATIONS...THERE APPEARS TO BE A
STRONG SIGNAL FOR FLASH FLOODING THROUGH A GOOD PORTION OF THE
NIGHT.

OTTO

ATTN...WFO...EAX...ILX...LSX...PAH...SGF...

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

LAT...LON   40039273 39168842 38008811 37958969 38239236 
            38659409 39139514 39789492