Close Window

Issued:

February 19, 2014 at 4:28 am CDT

Expires:

February 19, 2014 at 4:30 pm CDT

Event:

Hydrologic Outlook

Alert:

...URBAN AND RIVER FLOODING POSSIBLE BY THURSDAY... HIGH TEMPERATURES WILL BE WELL ABOVE FREEZING AGAIN TODAY RESULTING IN RAPID SNOW MELT WHERE SNOW STILL EXISTS ACROSS PARTS OF EAST CENTRAL AND SOUTHEAST ILLINOIS. TEMPERATURES ARE FORECAST TO CLIMB INTO THE UPPER 50S OR LOWER 60S ON THURSDAY. THESE VERY MILD TEMPERATURES WILL RESULT IN A GREATLY ACCELERATED SNOW MELT AND INCREASED RUNOFF. SNOW DEPTHS ACROSS THE OUTLOOK AREA GENERALLY RANGE FROM 4 TO 6 NORTH OF I-70...WITH UP TO 3 INCHES SOUTH OF I-70. MORE IMPORTANTLY...THE WATER EQUIVALENT OF THE EXISTING SNOW PACK IS ESTIMATED TO BE AROUND AN INCH IN MANY AREAS. FROST DEPTHS BELOW THE SNOW PACK RANGE FROM 8 TO 15 INCHES. A DEEP FROST LAYER WILL INHIBIT THE INFILTRATION OF WATER FROM SNOW MELT AND INCREASE THE RUNOFF INTO AREA RIVERS, STREAMS AND DITCHES. BASED ON CURRENT TEMPERATURE FORECASTS ALONE, RIVERS WILL CONTINUE RISING DUE TO THE SNOW MELT. THERE IS ALSO THE POTENTIAL FOR MODERATE TO HEAVY RAINFALL LATE TONIGHT AND THURSDAY AS A STRONG WEATHER SYSTEM MOVES THROUGH THE AREA. CURRENT FORECASTS SHOW RAINFALL AMOUNTS OF 0.50 TO 0.75 INCHES POSSIBLE OVER THE OUTLOOK AREA. IF HEAVY RAINFALL MATERIALIZES THAT WOULD INCREASE THE RATE OF RUNOFF AND SUBSEQUENT FLOODING. IN ADDITION...THE SNOW PACK AND MANY SNOW PILES IN CITY AND TOWN PARKING LOTS WILL MELT AND ALSO CONTRIBUTE TO THE POTENTIAL FOR FLOODING. THIS FLOODING WOULD AFFECT MAINLY CITY PARKING LOTS...STREETS...INTERSECTIONS...DRAINAGE BASINS...DITCHES...RESIDENTIAL AREAS WHERE STORM DRAINS ARE EITHER BLOCKED OR CLOGGED...AND OTHER LOW LYING AREAS IN POPULATED CENTERS. ANOTHER MAJOR CONCERN IS THE AMOUNT OF ICE COVER ON RIVERS ACROSS THE AREA. THE NATIONAL WEATHER SERVICE ICE SPOTTERS REPORT MANY RIVERS HAVE 100 PERCENT ICE COVER. AS THE RUNOFF BEGINS...STREAM FLOWS BENEATH THE ICE COVER WILL INCREASE WHICH WILL LIFT AND BREAK THE ICE. AS THE ICE MOVES DOWNSTREAM ICE JAMS ARE POSSIBLE. ICE JAMS CAN RESULT IN RAPID RISES OF WATER LEVELS AND SIGNIFICANT FLOODING IN THE VICINITY OF THE ICE JAM. PERSONS LIVING ALONG RIVERS AND IN FLOOD PRONE AREAS SHOULD PREPARE NOW FOR THE POSSIBILITY OF RIVER FLOODING IN THE COMING WEEKS. CONTINUE TO CLOSELY MONITOR THIS DEVELOPING SNOW MELT SITUATION. ANY SIGNIFICANT CHANGES IN PRECIPITATION AMOUNTS OR TEMPERATURES COULD AFFECT THE TIMING AND SEVERITY OF FLOODING. FOR DETAILED RIVER FORECAST AND FLOOD INFORMATION GO TO WEATHER.GOV/LINCOLN AND CLICK ON THE RIVERS AND LAKES LINK.

Instruction:

Target Area:

Clark; Clay; Coles; Crawford; Cumberland; Douglas; Edgar; Effingham; Jasper; Lawrence; Moultrie; Richland; Shelby

Close Window