THIS OUTLOOK IS FOR STREAMS WITHIN THE NWS CHICAGO HYDROLOGIC
SERVICE AREA...WHICH INCLUDES ILLINOIS RIVER TRIBUTARIES IN
NORTHEAST ILLINOIS AND NORTHWEST INDIANA. IT INCLUDES THE ILLINOIS
RIVER DOWN TO LA SALLE. IT ALSO INCLUDES STREAMS WITHIN THE ROCK
RIVER BASIN IN NORTH CENTRAL ILLINOIS AND THE ROCK RIVER FROM
ROCKTON DOWN TO DIXON ILLINOIS. THIS OUTLOOK IS FOR THE TIME PERIOD
FROM FEBRUARY THROUGH MAY.
...OUTLOOK BRIEF SUMMARY...
THIS WINTER HAS BEEN NOTED FOR ABOVE NORMAL TEMPERATURES AND LACK OF
SIGNIFICANT SNOW. BASED ON CURRENT CONDITIONS AT THE TIME THIS
OUTLOOK WAS RELEASED...THE RISK FOR MINOR FLOODING IS BELOW
NORMAL FOR STREAMS IN THE ROCK RIVER BASIN IN ILLINOIS. THE RISK FOR
MINOR FLOODING RANGES FROM NEAR NORMAL TO ABOVE NORMAL WITHIN
PORTIONS OF THE KANKAKEE RIVER BASIN. ELSEWHERE FOR TRIBUTARIES
WITHIN THE UPPER ILLINOIS BASIN...THE RISK FOR MINOR FLOODING IS
NEAR NORMAL. THE RISK FOR MINOR FLOODING ON THE ILLINOIS RIVER
MAINSTEM FROM MORRIS TO LA SALLE IS NEAR NORMAL. THE AMOUNT OF
RAINFALL OR ADDITIONAL SNOW AND SUBSEQUENT SNOWMELT IN THE COMING
WEEKS WILL DETERMINE THE SEVERITY OF ANY FUTURE FLOODING.
THIS SPRING OUTLOOK IS BASED ON HYDROLOGIC CONDITIONS INCLUDING THE
CURRENT SOIL MOISTURE...SNOWPACK...AND STREAMFLOW CONDITIONS AT THE
TIME OF ISSUANCE. IT SHOULD BE NOTED THAT HYDROLOGIC CONDITIONS CAN
CHANGE RAPIDLY DURING LATE WINTER AND EARLY SPRING. THESE OUTLOOKS
ARE ISSUED EACH LATE WINTER AND EARLY SPRING IN ADDITION TO THE 7
DAY RIVER FORECASTS THAT ARE ISSUED WHEN RIVER FORECAST LOCATIONS
ARE IN FLOOD OR ARE FORECAST TO RISE ABOVE FLOOD STAGE.
...CURRENT SNOW COVER AND LIQUID WATER EQUIVALENT...
THE ONLY SNOW REMAINING ACROSS THE AREA WAS IN ISOLATED AREAS OF
NORTHWEST INDIANA AS A RESULT OF LAKE EFFECT SNOW. SNOW DEPTHS
ACROSS PORTIONS OF JASPER AND PORTER COUNTIES IN NORTHWEST INDIANA
WERE BETWEEN 1 AND 3 INCHES. WATER EQUIVALENTS WERE LESS THAN 0.5
INCH.
...PAST PRECIPITATION AND SOIL CONDITIONS...
PRECIPITATION DURING THIS PAST FALL ACROSS NORTHERN ILLINOIS AND
NORTHWEST INDIANA WAS NEAR NORMAL AND TEMPERATURES AVERAGED ABOVE
NORMAL. THIS PAST WINTER HAS SEEN WELL ABOVE NORMAL TEMPERATURES AND
LESS THAN NORMAL SNOWFALL. SOIL MOISTURE WAS NEAR NORMAL. A SHALLOW
FROST LAYER EXISTED ACROSS NORTHERN ILLINOIS OF BETWEEN 2 AND 4
INCHES.
...RIVER CONDITIONS...
STREAMFLOW ON AREA RIVERS WAS NEAR NORMAL ACROSS NORTHERN ILLINOIS
AND NORTHWEST INDIANA. SOME LOCATIONS WITHIN THE KANKAKEE RIVER
BASIN HAD EXPERIENCED ABOVE NORMAL FLOWS IN PREVIOUS WEEKS BUT RIVER
LEVELS CONTINUED TO FALL. NWS CHICAGO RIVER ICE SPOTTERS REPORTED
THAT ICE WAS MINIMAL ON AREA STREAMS AS OF FEB 13. NO SIGNIFICANT
ICE JAM ISSUES HAVE BEEN EXPERIENCED THUS FAR THIS WINTER.
...WEATHER OUTLOOKS...
THE 6 TO 10 DAY OUTLOOK VALID FEB 21 TO FEB 25 INDICATES NORMAL
PRECIPITATION AND TEMPERATURES. THE LONG RANGE 30 DAY OUTLOOK FOR
MARCH INDICATES ABOVE NORMAL TEMPERATURES AND PRECIPITATION.
...FLOOD POTENTIAL SUMMARY...
BASED ON THE CURRENT SOIL MOISTURE...CURRENT STREAMFLOW...FROST
DEPTHS...SNOWPACK CONDITIONS...THE RISK FOR MINOR FLOODING IS
BELOW NORMAL FOR STREAMS IN THE ROCK RIVER BASIN IN
ILLINOIS. THE RISK FOR MINOR FLOODING RANGES FROM NEAR NORMAL TO
ABOVE NORMAL WITHIN PORTIONS OF THE KANKAKEE RIVER BASIN. ELSEWHERE
FOR TRIBUTARIES WITHIN THE UPPER ILLINOIS BASIN...THE RISK FOR MINOR
FLOODING IS NEAR NORMAL. THE RISK FOR MINOR FLOODING ON THE ILLINOIS
MAINSTEM FROM MORRIS TO LA SALLE IS NEAR NORMAL. THE AMOUNT OF
RAINFALL OR ADDITIONAL SNOW AND SUBSEQUENT SNOWMELT IN THE COMING
WEEKS WILL DETERMINE THE SEVERITY OF ANY FUTURE FLOODING.
...TABLE 1--PROBABILITIES FOR MINOR...MODERATE AND MAJOR
FLOODING...AND DEPARTURES FROM NORMAL OF REACHING FLOOD STAGE...
-----------FLOOD STAGE----------- DEPARTURE
LOCATION MINOR MODERATE MAJOR FROM NORMAL
STG PCT STG PCT STG PCT OF REACHING
FLOOD STAGE
PECATONICA RIVER
SHIRLAND IL 12.0 24% 15.0 --- 17.0 --- 13% LESS
ROCK RIVER
ROCKTON IL 10.0 19% 11.0 6% 14.0 --- 8% LESS
LATHAM PARK IL 10.0 14% 11.0 4% 14.0 --- 8% LESS
KISHWAUKEE RIVER
BELVIDERE IL 9.0 4% 11.0 1% 12.0 --- 8% LESS
S BR KISHWAUKEE
DEKALB IL 10.0 4% 11.0 1% 12.5 --- NEAR NORMAL
KISHWAUKEE RIVER
PERRYVILLE IL 12.0 29% 18.0 --- 22.0 --- 8% LESS
ROCK RIVER
BYRON IL 13.0 4% 16.0 1% 18.0 --- 6% LESS
DIXON IL 16.0 3% 18.0 3% 20.0 1% 9% LESS
KANKAKEE RIVER
DUNNS BRIDGE IN 10.0 26% 12.0 3% 13.0 --- 6% LESS
KOUTS IN 11.0 32% 13.0 3% 14.0 1% NEAR NORMAL
SHELBY IN 9.0 90% 11.0 36% 12.5 11% NEAR NORMAL
MOMENCE IL 5.0 36% 6.5 11% 9.0 1% NEAR NORMAL
WILMINGTON IL 6.5 16% 8.0 8% 10.0 1% NEAR NORMAL
IROQUOIS RIVER
RENSSELAER IN 12.0 36% 14.0 6% 15.0 6% 6% LESS
FORESMAN IN 18.0 24% 22.0 45 24.0 --- NEAR NORMAL
IROQUOIS IL 18.0 54% 24.0 4% 25.0 1% NEAR NORMAL
CHEBANSE IL 16.0 13% 18.0 4% 20.0 4% NEAR NORMAL
SUGAR CREEK
MILFORD IL 18.0 49% 22.0 6% 26.0 3% NEAR NORMAL
DES PLAINES RIVER
RUSSELL IL 7.0 62% 9.0 1% 10.0 --- NEAR NORMAL
GURNEE IL 7.0 19% 9.0 3% 11.0 1% 7% LESS
LINCOLNSHIRE IL 11.0 9% 14.0 3% 15.5 1% NEAR NORMAL
DES PLAINES IL 5.0 9% 8.0 1% 9.0 1% NEAR NORMAL
RIVERSIDE IL 7.0 18% 8.0 6% 9.0 1% NEAR NORMAL
ROMEOVILLE IL 12.5 31% 13.0 9% 13.5 --- NEAR NORMAL
E BR DUPAGE RIVER
BOLINGBROOK IL 19.5 39% 21.0 3% 23.0 --- 7% LESS
DU PAGE RIVER
SHOREWOOD IL 6.5 9% 8.0 --- 10.0 --- 8% LESS
MAZON RIVER
COAL CITY IL 12.0 9% 14.0 --- 17.0 --- 8% LESS
FOX RIVER
ALGONQUIN TW 9.5 32% 10.5 13% 12.0 6% 13% LESS
MONTGOMERY IL 13.0 42% 14.0 4% 15.0 --- 9% LESS
DAYTON IL 12.0 31% 14.0 13% 24.0 --- 12% LESS
VERMILION RIVER
PONTIAC IL 14.0 13% 15.0 8% 18.0 1% NEAR NORMAL
LEONORE IL 16.0 34% 21.0 6% 26.0 --- NEAR NORMAL
THORN CREEK
THORNTON IL 10.0 13% 15.0 --- 16.0 --- 8% LESS
LITTLE CALUMET R
MUNSTER IN 12.0 34% 14.0 9% 17.0 --- 9% LESS
SOUTH HOLLAND IL 16.5 --- 18.0 --- 20.0 --- NA
HART DITCH
DYER IN 12.0 1% 13.0 --- 14.0 1% NEAR NORMAL
ILLINOIS RIVER
MORRIS IL 16.0 34% 18.0 18% 22.0 3% 6% LESS
OTTAWA IL 463.0 27% 466.0 13% 469.0 3% 6% LESS
LA SALLE IL 20.0 68% 27.0 11% 31.0 1% NEAR NORMAL
...TABLE 2--EXCEEDANCE PROBABILITIES...
IN THE TABLE BELOW...THE 90 THROUGH 10 PERCENT COLUMNS INDICATE
THE CHANCE THAT A LOCATION ON A RIVER COULD RISE ABOVE THE LISTED
STAGE LEVELS DURING THE INDICATED PERIOD.
FOR EXAMPLE: THE KANKAKEE RIVER AT DUNNS BRIDGE HAS A FLOOD STAGE OF
10 FEET. THERE IS A 80 PERCENT CHANCE THE RIVER WILL RISE TO 7.4
FEET OR ABOVE.
LOCATION FS (FT) 90% 80% 70% 60% 50% 40% 30% 20% 10%
-------- ------- --- --- --- --- --- --- --- --- ---
KANKAKEE RIVER
DUNNS BRIDGE 10.0 7.9 8.5 8.8 9.1 9.4 9.7 10.0 10.3 11.0
KOUTS 11.0 9.0 9.6 9.9 10.2 10.6 10.8 11.1 11.5 12.1
SHELBY 9.0 9.1 9.4 9.9 10.2 10.8 10.9 11.4 12.1 13.5
MOMENCE 5.0 3.4 3.7 3.9 4.2 4.5 4.9 5.1 5.7 6.8
WILMINGTON 6.5 3.5 4.0 4.5 4.8 5.2 5.5 5.7 6.1 7.1
SUGAR CREEK
MILFORD 18.0 12.9 16.2 17.0 17.5 18.0 18.5 19.2 19.5 21.2
IROQUOIS RIVER
RENSSELAER 12.0 9.2 10.0 10.2 11.0 11.4 11.8 12.2 12.8 13.7
FORESMAN 18.0 13.8 14.2 14.9 15.8 16.5 16.8 17.5 18.2 19.0
IROQUOIS 18.0 14.2 15.3 16.9 17.6 18.6 20.0 20.7 21.4 22.0
CHEBANSE 16.0 9.0 9.7 10.8 11.5 12.3 12.8 13.8 15.2 16.6
DES PLAINES RIVER
RUSSELL 7.0 5.1 6.5 6.8 7.0 7.2 7.3 7.5 7.6 7.8
GURNEE 7.0 4.2 4.6 5.0 5.6 5.9 6.2 6.8 7.1 7.7
DES PLAINES 5.0 1.8 2.0 2.3 2.5 2.7 3.3 3.8 4.4 5.9
LINCOLNSHIRE 12.5 9.0 9.5 9.8 10.2 10.6 10.9 11.5 11.9 12.7
RIVERSIDE 7.0 4.8 5.3 5.6 5.8 6.1 6.3 6.6 6.9 7.6
FOX RIVER
ALGONQUIN TAILW 9.5 7.4 7.9 8.2 8.7 9.2 9.4 9.6 10.3 11.5
MONTGOMERY 13.0 12.1 12.5 12.7 12.8 12.9 13.0 13.1 13.4 13.6
DAYTON 12.0 8.7 9.4 10.0 10.7 11.3 11.8 12.0 12.7 14.4
EAST BR DU PAGE RIVER
BOLINGBROOK 19.5 17.5 18.0 18.5 18.8 19.1 19.6 19.8 20.1 20.6
DU PAGE RIVER
SHOREWOOD 6.5 3.9 4.6 4.8 5.1 5.3 5.6 6.0 6.2 6.5
MAZON RIVER
COAL CITY 12.0 4.4 5.7 6.6 8.0 8.7 9.9 10.2 10.7 12.1
VERMILION RIVER
PONTIAC 14.0 6.1 6.8 7.3 8.3 9.5 10.0 11.3 13.3 14.9
LEONORE 16.0 9.5 10.1 11.8 12.6 14.3 15.6 16.5 18.0 20.8
THORN CREEK
THORNTON 10.0 4.9 6.0 6.8 7.2 7.7 8.3 8.9 9.7 10.6
HART DITCH
DYER 12.0 4.1 4.5 5.1 5.4 5.8 6.0 6.4 7.2 7.7
LITTLE CALUMET RIVER
MUNSTER 12.0 9.5 9.9 10.5 10.9 11.2 11.8 12.3 12.6 14.2
SOUTH HOLLAND 16.5 9.6 11.0 11.6 11.9 12.2 12.9 13.2 13.9 14.4
ILLINOIS RIVER
MORRIS 16.0 8.7 9.9 12.4 13.7 14.7 15.5 16.8 17.9 20.8
OTTAWA 463.0
LA SALLE 20.0 15.5 17.7 20.1 22.1 23.0 23.3 24.1 25.9 28.9
KISHWAUKEE RIVER
BELVIDERE 9.0 3.9 4.6 5.3 5.9 6.3 6.6 7.1 8.1 8.8
PERRYVILLE 12.0 8.7 9.3 9.9 10.4 10.8 11.4 12.0 12.3 13.8
SOUTH BRANCH KISHWAUKEE RIVER
DE KALB 10.0 5.3 5.7 6.5 6.8 7.0 7.5 8.2 8.5 9.1
ROCK RIVER
ROCKTON 10.0 5.4 5.8 6.4 6.8 7.7 8.4 8.8 10.0 10.8
LATHAM PARK 10.0 5.7 6.0 6.5 6.8 7.7 8.2 8.6 9.7 10.3
ROCKFORD 9.0 3.1 3.2 3.3 3.3 3.5 3.7 3.8 4.2 4.5
BYRON 13.0 8.1 8.5 9.0 9.4 10.3 10.8 11.4 12.0 12.6
DIXON 16.0 10.3 10.9 11.3 11.9 12.5 13.0 13.4 14.1 14.8
PECATONICA RIVER
SHIRLAND 12.0 7.7 8.1 8.7 9.8 10.4 10.9 11.3 12.2 13.1
THE NATIONAL WEATHER SERVICE CHICAGO OFFICE IN ROMEOVILLE ISSUES LONG
RANGE AHPS OUTLOOKS FOR ALL RIVER FORECAST LOCATIONS. THIS PRODUCT IS
UPDATED MONTHLY AROUND MID-MONTH. THESE OUTLOOKS ARE ISSUED IN
ADDITION TO THE 5 DAY RIVER FORECASTS THAT ARE ISSUED WHEN RIVER
FORECAST LOCATIONS ARE IN FLOOD OR FORECAST TO RISE ABOVE FLOOD
STAGE.
THIS LONG-RANGE PROBABILISTIC OUTLOOK CONTAINS FORECAST VALUES THAT
ARE CALCULATED USING MULTIPLE SEASON SCENARIOS FROM 30 OR MORE YEARS
OF CLIMATOLOGICAL DATA INCLUDING CURRENT CONDITIONS OF THE RIVER...
SOIL MOISTURE...AND 30 TO 90 DAY LONG-RANGE OUTLOOKS OF TEMPERATURE
AND PRECIPITATION.
BY PROVIDING THE COMPLETE RANGE OF PROBABILISTIC NUMBERS...THE LEVEL
OF RISK ASSOCIATED WITH LONG-RANGE PLANNING DECISIONS CAN BE
DETERMINED. THESE PROBABILISTIC FORECASTS ARE PART OF THE NATIONAL
WEATHER SERVICE ADVANCED HYDROLOGIC PREDICTION SERVICE.
VISIT OUR WEB PAGE AT WEATHER.GOV/CHICAGO FOR MORE WEATHER AND RIVER
INFORMATION INCLUDING GRAPHS OF PROBABILISTIC RIVER OUTLOOKS.
...FLOOD TERMINOLOGY...
MINOR FLOODING IS USED TO INDICATE MINIMAL OR NO PROPERTY
DAMAGE. HOWEVER SOME PUBLIC INCONVENIENCE IS POSSIBLE.
MODERATE FLOODING IS USED TO INDICATE THE INUNDATION OF SECONDARY
ROADS. TRANSFER TO HIGHER ELEVATIONS MAY BE NECESSARY TO SAVE
PROPERTY. SOME EVACUATIONS MAY BE REQUIRED.
MAJOR FLOODING IS USED TO INDICATE EXTENSIVE INUNDATION AND PROPERTY
DAMAGE USUALLY CHARACTERIZED BY EVACUATION OF PEOPLE AND LIVESTOCK
AND CLOSURE OF BOTH PRIMARY AND SECONDARY ROADS.
VISIT OUR WEB PAGE AT WEATHER.GOV/CHICAGO FOR MORE WEATHER AND RIVER
INFORMATION INCLUDING GRAPHS OF PROBABILISTIC RIVER OUTLOOKS.
THE NEXT UPDATED SPRING FLOOD AND WATER RESOURCES OUTLOOK WILL BE
ISSUED ON THURSDAY MARCH 1.
NATIONAL FLOOD AWARENESS WEEK WILL BE MARCH 12 TO MARCH 16 2012.
