HYDROLOGIC OUTLOOK
Warning Issue Date: 902 PM CST TUE DEC 22 2009
RENEWED RISES ON AREA RIVERS POSSIBLE LATER THIS WEEK...
A VERY STRONG LOW WILL MOVE INTO NORTHEAST IOWA BY FRIDAY
MORNING. THIS WILL BRING A MIXTURE OF PRECIPITATION
TONIGHT...WEDNESDAY AND THURSDAY INTO NORTHERN ILLINOIS AND
NORTHWEST INDIANA. THE PRECIPITATION WILL BEGIN AS SNOW AND SLEET
OVERNIGHT AND WILL CHANGE TO FREEZING DRIZZLE. WE EXPECT FREEZING
RAIN WEDNESDAY NIGHT AND EARLY THURSDAY MORNING. THEN...RAIN WILL
FALL OVER THE AREA THURSDAY. THERE IS SNOW ON THE GROUND AND THE
ADDITIONAL 1 TO 2 INCHES OF RAIN WITH SNOWMELT WILL ADD SIGNIFICANT
RUNOFF TO AREA RIVERS. SOME LOCAL RIVERS AND CREEKS MAY RISE
THURSDAY AND FRIDAY.
SNOW DEPTHS WERE GREATEST WITHIN PORTIONS OF THE ROCK...UPPER
FOX...AND UPPER DES PLAINES RIVER BASINS WHERE DEPTHS WERE BETWEEN 4
AND 8 INCHES. WATER EQUIVALENT OF THE SNOWPACK IN THOSE AREAS WAS
AROUND 1 INCH. FURTHER SOUTH...SNOW DEPTHS WERE BETWEEN 2 AND 4
INCHES WITH WATER EQUIVALENTS GENERALLY BELOW ONE HALF INCH.
REPORTED FROST DEPTHS WERE BETWEEN 2 AND 4 INCHES. ALTHOUGH RIVERS
WERE CURRENTLY BELOW FLOOD STAGE...FLOWS WERE SLIGHTLY ABOVE
NORMAL.
A COMBINATION OF HEAVY RAIN AND SNOWMELT OVER FROZEN GROUND WOULD
RESULT IN RISES ON AREA STREAMS WITH SOME RISES POSSIBLY ABOVE FLOOD
STAGE.
RESIDENTS IN LOW LYING FLOOD PRONE AREAS ALONG AREA RIVERS AND
CREEKS SHOULD CONTINUE TO MONITOR THIS DEVELOPING WEATHER SYSTEM.
$$
FLOOD WATCH
Warning Issue Date: 345 AM CST WED DEC 23 2009
/
...FLOOD WATCH IN EFFECT FROM THURSDAY AFTERNOON THROUGH LATE
THURSDAY NIGHT...
THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A
* FLOOD WATCH FOR PORTIONS OF ILLINOIS AND INDIANA...INCLUDING
THE FOLLOWING AREAS...IN ILLINOIS...BOONE...COOK...DE KALB...
DUPAGE...FORD...GRUNDY...IROQUOIS...KANE...KANKAKEE...
KENDALL...LA SALLE...LAKE IL...LEE...LIVINGSTON...MCHENRY...
OGLE...WILL AND WINNEBAGO. IN INDIANA...BENTON...JASPER...LAKE
IN...NEWTON AND PORTER.
* FROM THURSDAY AFTERNOON THROUGH LATE THURSDAY NIGHT.
* HEAVY RAIN IS EXPECTED TO DEVELOP ACROSS NORTHERN ILLINOIS AND
NORTHWEST INDIANA BY THURSDAY AFTERNOON AND CONTINUE THROUGH
EARLY FRIDAY MORNING. STORM TOTAL RAINFALL AMOUNTS OF 1 TO 2
INCHES WILL BE COMMON. SOME AREAS MAY RECEIVE AS MUCH AS 3
INCHES BY FRIDAY MORNING.
* THE DEPTH OF THE CURRENT SNOW PACK RANGES FROM 5 TO 8 INCHES
OVER NORTHWEST ILLINOIS TO 1 TO 3 INCHES ACROSS NORTHWEST
INDIANA. AS THIS SNOW MELTS...COMBINED WITH THE EXPECTED HEAVY
RAIN...AND FROZEN GROUND CONDITIONS...RAPID RUNOFF AND RISES ON
AREA RIVERS ARE EXPECTED. SOME RIVERS MAY REACH OR EXCEED FLOOD
STAGE. FLOODING OF LOW LYING AND FLOOD PRONE AREAS WILL ALSO BE
POSSIBLE.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A FLOOD WATCH MEANS THERE IS A POTENTIAL FOR FLOODING BASED ON
CURRENT FORECASTS.
YOU SHOULD MONITOR LATER FORECASTS AND BE ALERT FOR POSSIBLE
FLOOD WARNINGS. THOSE LIVING IN AREAS PRONE TO FLOODING SHOULD BE
PREPARED TO TAKE ACTION SHOULD FLOODING DEVELOP.
$$
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