...HEAVY RAINFALL LIKELY TO RESULT IN FLOODING AND POTENTIALLY
SIGNIFICANT FLOODING LATE TUESDAY INTO TUESDAY NIGHT...
A SLOW MOVING AND STRONG STORM SYSTEM IS FORECAST TO TRANSPORT
RECORD WARMTH AND RECORD LEVEL VALUES OF MOISTURE INTO THE REGION
ON TUESDAY. TO PUT INTO PERSPECTIVE HOW MOIST THE ATMOSPHERE IS
FORECAST TO BECOME...MOISTURE CONTENT BY TUESDAY AFTERNOON WILL BE
COMPARABLE WITH AVERAGE MOISTURE CONTENT OF A TYPICAL JULY DAY AND
MUCH ABOVE AVERAGE FOR EVEN APRIL. THIS RECORD WARM AND MOIST AIR
COMBINED WITH A SLOW MOVING AND STRONG FRONT COULD RESULT IN
WIDESPREAD HEAVY RAINFALL OVER PORTIONS OF THE REGION. AT THIS
TIME...THE GREATEST THREAT OF HEAVY RAINFALL LOOKS EXTEND FROM THE
CHICAGO AREA SOUTHWEST TO LASALLE PERU AND EAST INTO NORTHWEST
INDIANA...BUT EVEN AREAS FARTHER WEST OVER NORTH CENTRAL ILLINOIS
COULD SEE RAINFALL TOTALS OVER AN INCH THE NEXT 48 HOURS.
THIS RAIN WILL FALL ON A GROUND THAT IS FROZEN TO GREAT DEPTHS
RESULTING IN VERY HIGH RUNOFF RATES...WHICH WILL RESULT IN A
FASTER THAN NORMAL RESPONSE ON AREA STREAMS AND RIVERS. THE
QUICKLY INCREASING STREAM FLOW AND RECORD WARM TEMPERATURES WILL
RESULT IN A RAPID BREAK UP OF ICE ON RIVERS AND AN ELEVATED RISK
OF ICE JAM FLOODING.
IN ADDITION TO THE USUAL UNCERTAINTIES WITH RESPECT TO THE
RAINFALL FORECAST...THERE IS ALSO SOME ADDITIONAL UNCERTAINTY IN
THE MAGNITUDE OF THE FLOOD THREAT BECAUSE STREAM FLOW ACROSS THE
AREA IS CURRENTLY BELOW TO MUCH BELOW AVERAGE. DESPITE LOWER THAN
AVERAGE STREAM FLOW...THE FORECASTED MAGNITUDE OF THE RAINFALL
SUGGESTS A HIGH POTENTIAL FOR FLOODING AND SHOULD RAINFALL AMOUNTS
END UP ON THE UPPER END OF THE POTENTIAL RANGE THEN MAJOR FLOODING
COULD OCCUR IN SOME AREAS. THE POTENTIAL FOR ICE JAMS FURTHER
INCREASES THE FLOOD THREAT. PERSONS IN FLOOD PRONE AND LOW LYING
AREAS SHOULD MONITOR LATER FORECASTS AND STATEMENTS ON THE HEAVY
RAIN AND FLOOD POTENTIAL.
A FLOOD WATCH FOR TUESDAY AFTERNOON INTO TUESDAY NIGHT WILL
LIKELY BE ISSUED FOR MUCH OF THE REGION LATER THIS AFTERNOON OR
TONIGHT.
