MESOSCALE PRECIPITATION DISCUSSION 0018...CORRECTION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
508 PM EDT TUE APR 23 2013
 
AREAS AFFECTED...PORTIONS OF SOUTHEAST ILLINOIS, NORTHWEST
INDIANA, AND SOUTHERN MICHIGAN 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 232050Z - 240135Z
 
...CORRECTION FOR GRAMMAR...

AN AREA OF MODERATE TO HEAVY RAINFALL IS EXPECTED TO MOVE ACROSS
THE REGION WITHIN A VERY DIFFLUENT AREA ALOFT AND WITHIN A REGIME
WITH PRECIPITABLE WATER VALUES AT OR AROUND 1.25 INCHES. AN AREA
OF CONVECTION IS EXPECTED TO FORM BY 7 PM CDT ACROSS SOUTHERN
ILLINOIS, ST. LOUIS AND WESTERN PORTIONS OF INDIANA, WITH THE AREA
MOVING EAST TO NORTHEASTWARD WITH TIME.  A WEAK WARM
FRONT/BAROCLINIC TROUGH SHOULD PUSH NORTHEAST ACROSS THE REGION
AHEAD OF A STRONGER NORTHEAST-SOUTHWEST ORIENTED FRONTAL BOUNDARY
WITH ASSOCIATED DECENT LOW- TO MID-LEVEL FRONTOGENESIS.  A PLUME
OF STRONG LOW-LEVEL -- 850 HPA -- INFLOW OF 40-50 KNOTS MOVES FROM
WEST TO EAST ACROSS EASTERN ILLINOIS AND INDIANA.  LOCAL AMOUNTS
OF 2 INCHES ARE POSSIBLE IN A SHORT PERIOD OF TIME WITHIN THIS
MOIST AIR MASS.  PORTIONS OF THIS AREA ARE ALREADY IN A RIVER
FLOOD SITUATION, WITH RAINFALL AS LOW AS ONE INCH IN A FEW HOURS'
TIME EXPECTED TO EXACERBATE ISSUES.  THE CITIES OF ST. LOUIS AND
INDIANAPOLIS WERE ALSO INCLUDED AS FLASH FLOODING IN URBAN AREAS
IS POSSIBLE IN SITUATIONS WHERE 1-2 INCHES OF RAINFALL FALLS
WITHIN A SHORT PERIOD OF TIME.

ROTH

ATTN...WFO...CLE...ILN...DTX...LMK...IWX...GRR...IND...PAH...
LOT...ILX...LSX...

LAT...LON   41758715 42288627 43168494 43198394 42418333 41448378
            39188603 37948739 38008862 38118972 38369133 39559005
            40418911 41758715