MESOSCALE PRECIPITATION DISCUSSION 0016
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
852 PM EDT THU APR 18 2013
 
AREAS AFFECTED...ERN IL/WRN IN 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 190049Z - 190349Z
 
SUMMARY...A SFC COLD FRONT ADVANCING FROM THE W IS EXPECTED TO
BRING MDT TO HEAVY RAINFALL TO REGIONS WHICH ALREADY SAW 1 TO 2
INCHES OF PCPN FROM EARLIER CONVECTION.

DISCUSSION...RADAR IMAGERY DEPICTED AN AXIS OF CONVECTION MOVING
TOWARD THE UPR OH VALLEY WITH THE ACTIVITY WANING AS IT INTERSECTS
A REGION OF MORE STABLE AIR AS INDICATED BY LOCAL 00Z RAOBS AND
23Z RAP INSTABILITY PARAMETERS. FURTHER UPSTREAM...A STRONG
BAROCLINIC ZONE/COLD FRONT WAS SEEN PRODUCING HEAVY AREAS OF
RAINFALL AS IT BISECTS AN AIR MASS WITH ABOVE 1.75 IN PWATS. THE
PAST SEVERAL SCANS ON THE RADAR SUGGEST THE ACTIVITY ACRS SRN IL
HAS FURTHER ENHANCED SUGGESTING 1 TO 2 INCHES OF ADDITIONAL
RAINFALL WILL BE POSSIBLE OVER ERN IL/WRN IN. GIVEN THE EARLIER
OUTFLOW BNDRY PRODUCED AN EXPANSIVE AREA OF 1.50 TO 2 INCHES OF
RAIN PER METARS/NSSL QPE...ANY ADDITIONAL HEAVY RAINFALL MAY
PRODUCE FLASH FLOODING. THE 6-HR FFG GUIDANCE IS RATHER VARIABLE
RANGING FROM 1.50 TO 2.50 INCHES WITH EXPECTED AMTS APPROACHING
THIS RANGE. FORTUNATELY...GUIDANCE SUGGESTS THIS AREA OF FRONTAL
CONVECTION SHOULD BE OF A SHORTER DURATION AS THE 500-MB TROF HAS
BEGUN TO SHIFT EWRD.

RUBIN-OSTER


ATTN...WFO...IWX...IND...LOT...ILX...

LAT...LON   39418801 40198798 41278794 41548717 41198676 40238655
            39278701 39418801