846  
FGUS63 KMSR 241611  
ESGMSR  
 
UPPER MIDWEST SPRING SNOWMELT AND FLOOD POTENTIAL OUTLOOK  
NWS NORTH CENTRAL RIVER FORECAST CENTER TWIN CITIES/CHANHASSEN MN  
1010 AM CST WED FEB 24 2021  
 
THIS IS THE SECOND IN A SERIES OF OUTLOOKS TO DISCUSS THE POTENTIAL  
FOR FLOODING THIS SPRING.  
 
TO VIEW THE NCRFC 2021 SPRING HYDROLOGIC OUTLOOK WEBPAGE, WHICH  
CONTAINS SEVERAL REFERENCE GRAPHICS PERTAINING TO THE SNOWMELT  
SEASON ANTECEDENT AND CURRENT HYDROMETEOROLOGICAL CONDITIONS, REFER  
TO: HTTP://WWW.WEATHER.GOV/NCRFC AND SELECT THE SEASONAL OUTLOOK  
TAB AT THE TOP-RIGHT OF THE PAGE.  
 
THIS OUTLOOK REFERENCES INFORMATION FROM MANY SOURCES, INCLUDING THE  
FOLLOWING CORE PARTNERS:  
- US ARMY CORPS OF ENGINEERS (USACE)  
- UNITED STATES GEOLOGICAL SURVEY (USGS)  
- REGIONAL CLIMATE CENTERS (MIDWEST-MRCC AND HIGH PLAINS-HPRCC)  
- US DROUGHT MONITOR (NIDIS)  
- NOAA, OFFICE OF WATER PREDICTION (OWP), FORMERLY KNOWN AS  
NATIONAL OPERATIONAL HYDROLOGIC REMOTE SENSING CENTER (NOHRSC)  
 
THE FOLLOWING 2021 SPRING OUTLOOK ISSUANCE DATES HAVE BEEN SET IN  
COORDINATION WITH ALL NWS REGIONS AND NWS HEADQUARTERS:  
 
NATIONAL WEATHER SERVICE ISSUES SPRING FLOOD OUTLOOK WITH  
PROBABILISTIC PRODUCTS ON:  
* THURSDAY, FEBRUARY 11, 2021  
* THURSDAY, FEBRUARY 25, 2021  
* THURSDAY, MARCH 11, 2021  
 
NOAA NATIONAL SPRING FLOOD OUTLOOK PRESS BRIEFING WILL BE ON:  
* THURSDAY, MARCH 18, 2021  
 
***************************************  
SPRING 2021 NCRFC AREA SUMMARY UPDATE  
***************************************  
 
OVERALL, THE RISK FOR SPRING SNOWMELT FLOODING REMAINS LOWER THAN  
IN A TYPICAL YEAR ACROSS THE HUDSON BAY DRAINAGE, AND ALSO FOR MANY  
OF THE BASINS THAT DRAIN INTO THE GREAT LAKES. HOWEVER, THE RISK FOR  
SPRING SNOWMELT FLOODING IS ABOVE AVERAGE FROM IOWA AND NORTHERN  
MISSOURI, INTO NORTHERN ILLINOIS AND SOUTHERN WISCONSIN. ELSEWHERE  
ACROSS THE NCRFC SERVICE AREA, THE RISK IS ABOUT NORMAL.  
 
OVERALL, 101 FORECAST POINTS IN THE NCRFC AREA SHOW A 50% OR  
GREATER CHANCE FOR FLOODING THROUGH MAY 31ST, WITH ONLY 9 OF THOSE  
INDICATING A 50% OR GREATER CHANCE FOR MODERATE OR MAJOR FLOODING.  
THIS IS VERY SIMILAR TO OUR INITIAL OUTLOOK 2 WEEKS AGO. FOR  
PERSPECTIVE, THERE ARE 475 FORECAST LOCATIONS IN THE NCRFC  
SERVICE AREA.  
 
THE HIGHEST LIKELIHOOD FOR FLOODING RISKS IN THE NCRFC SERVICE AREA  
CONTINUES TO BE ALONG THE MISSISSIPPI RIVER DOWNSTREAM OF DAM 15, AS  
WELL AS ILLINOIS AND EASTERN IOWA TRIBUTARIES THAT FEED INTO THE  
MAINSTEM MISSISSIPPI RIVER.  
 
A MORE DETAILED LOOK AT THE CONDITIONS AND RISK BY REGIONAL AREA  
IS PROVIDED BELOW.  
   
..BASIN CONDITIONS AS OF FEBRUARY 24, 2021
 
 
NOT A GREAT DEAL HAS CHANGED SINCE OUR LAST OUTLOOK ON FEB 10TH.  
THE REGION WAS IN THE GRIPS OF A VERY DEEP AND COLD AIR MASS, WHICH  
PERSISTED UNTIL ABOUT FEB 20TH. BUT NOW WE HAVE REBOUNDED TO NORMAL  
TO ABOVE NORMAL TEMPERATURES. WE ALSO HAVE ADDED A LITTLE MORE SNOW  
TO THE LANDSCAPE, FROM IOWA AND EASTERN MINNESOTA, TO WISCONSIN AND  
NORTHERN ILLINOIS, AND OVER INTO MICHIGAN. FURTHER WEST, SNOW COVER  
REMAINS LIMITED OVER WESTERN MINNESOTA INTO THE DAKOTAS.  
 
THE WATER CONTENT OF THE SNOW INCREASED A LITTLE FROM IOWA AND  
EASTERN MINNESOTA, TO WISCONSIN AND NORTHERN ILLINOIS, AND INTO  
MICHIGAN. THE MOST NOTABLE AREA OF SNOW AND SNOW WATER CONTENT IS  
FROM THE EASTERN HALF OF IOWA, ACROSS NORTHERN ILLINOIS AND SOUTHERN  
WISCONSIN, WHERE A WIDESPREAD AREA OF 2.5 TO 4 INCHES OF WATER IS  
ON THE GROUND. SOME SPOTS WERE ALSO UP BETWEEN 4 AND 5 INCHES ALONG  
THE ILLINOIS AND WISCONSIN BORDER AREA. THIS IS WELL ABOVE THE NORM  
FOR THESE AREAS FOR THE LATTER PART OF FEBRUARY.  
 
MEANWHILE, FURTHER WEST, THE SNOW WATER CONTENT IS WELL BELOW THE  
NORM, WITH AROUND AN INCH OR LESS OF WATER AVAILABLE FOR MELTING FOR  
THE MAJORITY OF THE HUDSON BAY DRAINAGE.  
 
THE COLD ALSO HAD A FEW OTHER EFFECTS...FROST DEPTH AND RIVER ICE.  
 
THE FROST HAS GONE A BIT DEEPER OVERALL SINCE OUR LAST OUTLOOK. BUT  
FROST DEPTH OVERALL REMAINS MORE SHALLOW THAN IN A TYPICAL YEAR.  
DEPTH WAS 1-2 FEET FROM SOUTHERN MINNESOTA INTO NORTHERN WISCONSIN,  
WITH DEPTH OF 2 TO 3 FEET FROM NORTH DAKOTA INTO NORTHERN MINNESOTA.  
BUT THE HEAVIER SNOW FROM IOWA TO MICHIGAN PROVIDED AN INSULATING  
BLANKET, AND KEPT THE COLD FROM PENETRATING THE SOIL MUCH. FROST DEPTH  
IN THOSE AREAS REMAINS 6 INCHES OR LESS.  
 
RIVER ICE GREATLY INCREASED IN THE PAST FEW WEEKS, THANKS TO THE  
PROLONGED EXTREME COLD. WE DID SEE SOME MINOR ICE JAMMING AND DAMMING  
EFFECTS IN SOME OF OUR RIVER SYSTEMS, BUT OVERALL, THE IMPACT HAS  
BEEN MINIMAL TO THIS POINT. WHERE ICE THICKENED, WE NOW MUST WATCH  
FOR POTENTIAL JAMMING ONCE THE ICE STARTS TO BREAK UP. AS TEMPERATURES  
WARM AND SNOW MELTS, THE RESULTING RISE IN RIVER LEVELS WILL HELP  
BREAK UP THE ICE COVER AND ALLOW IT TO MOVE DOWNSTREAM. THE LOCATION  
OF JAMS IS HARD TO PREDICT, BUT IT DOES REMAIN POSSIBLE IN AREAS WHERE  
THERE IS SOME KIND OF RESTRICTION IN THE RIVER CHANNEL, INCLUDING  
BRIDGES, SHARP BENDS, OR WHERE OTHER BLOCKAGES ARE.  
 
THE OUTLOOK FOR THE REST OF FEBRUARY SUGGESTS TEMPERATURES NEAR THE  
NORMAL, WITH SLIGHTLY ABOVE NORMAL PRECIPITATION. AS WE MOVE INTO  
MARCH, TEMPERATURES LOOK TO BE ABOVE NORMAL, AND PRECIPITATION WILL  
VARY FROM BELOW NORMAL OVER THE DAKOTAS, TO ABOVE NORMAL EAST OF A  
LINE FROM MISSOURI TO WISCONSIN.  
 
FOR A MORE DETAILED DISCUSSION ON SPECIFIC WATERSHEDS, PLEASE  
CONTINUE READING BELOW.  
 
**********************  
GREAT LAKES DRAINAGE  
**********************  
 
OVERALL, THE RISK FOR FLOODING IS NORMAL OR EVEN A BIT BELOW NORMAL  
FOR THIS SPRING. IF FLOODING OCCURS, AT THIS TIME IT APPEARS THAT  
MAINLY MINOR FLOODING WILL BE THE RESULT.  
 
SNOW COVER AND SNOW WATER CONTENT DID INCREASE SOME OVER THE GREAT  
LAKES DRAINAGE OVER THE PAST 2 WEEKS. FOR AREAS FROM THE MINNESOTA  
ARROWHEAD OVER TO MICHIGAN, THIS IS BRINGING IT UP CLOSER TO A MORE  
TYPICAL SITUATION FOR THIS POINT IN THE SEASON. FOR AREAS FROM GREEN  
BAY AND MILWAUKEE, DOWN TO THE CHICAGO AREA, SNOW AND SNOW WATER IS  
MUCH ABOVE NORMAL FOR THIS TIME OF YEAR. SO THE RISK FOR ANY FLOODING  
APPEARS TO BE HIGHEST IN THOSE AREAS, DEPENDING ON HOW THE MELTING  
PERIOD PROGRESSES.  
 
SNOW DEPTH WAS GREATEST ALONG THE LAKE SUPERIOR SHORES IN THE UPPER  
PENINSULA, WITH THE TYPICAL SNOWY AREAS SEEING A SNOW PACK UP OVER  
40 INCHES. BUT OUTSIDE OF THE U.P. AMOUNTS WERE MUCH LOWER. THE LAKE  
EFFECT AREAS IN WESTERN LOWER MICHIGAN HAD SOME SNOW DEPTH IN THE  
12-15 INCH RANGE, AND WERE AS LOW AS ONLY 4-8 INCHES IN THE SOUTHEAST  
PART OF THE STATE NEAR DETROIT. WATER EQUIVALENT IN THE SNOW WAS  
OVER 6 OR 7 INCHES IN THE SNOWIER PART OF THE U.P. BUT WAS 2 TO 4  
INCHES OVER WESTERN LOWER MICHIGAN, AND AROUND AN INCH IN THE  
SOUTHEAST PART OF THE STATE.  
 
THE HEAVIER SNOW BAND FROM EASTERN IOWA OVER TOWARD THE MILWAUKEE AND  
NORTHERN CHICAGO SUBURB AREAS HAS 8 TO 15 INCHES, AND SOME HIGHER  
TOTALS HAVE BEEN REPORTED. WATER CONTENT IS FROM 2.5 TO 4 INCHES,  
WITH SOME HIGHER REPORTS.  
 
SNOW UP IN NORTHERN MINNESOTA IS LESS THAN AVERAGE WITH 12 TO 18  
INCHES OF DEPTH AT MOST, WITH WATER CONTENT OF 3 TO 4.5 INCHES.  
 
LAKE LEVELS HAVE BEEN RUNNING HIGH FOR SOME TIME NOW, INCLUDING  
RECORD HIGHS DURING 2019 AND 2020. BUT THE TREND HAS BEEN LOWER FOR  
THE PAST YEAR. STILL, WATER LEVELS ABOVE THE LONG-TERM AVERAGE  
COULD LEAD TO SOME PROBLEMS ALONG THE LAKE SHORE DURING LARGER  
STORM EVENTS, AS WIND EFFECTS DRIVE ICE AND WAVES ONTO THE SHORELINE.  
 
THE DEEP COLD IN THE FIRST HALF OF FEBRUARY CAUSED AN INCREASE IN  
ICE IN AREA CREEKS AND RIVERS. THERE HAVE BEEN A FEW ICE JAMS  
REPORTED, MOST NOTABLY IN WISCONSIN AND MICHIGAN. BUT EFFECTS AND  
EXTENT HAVE BEEN MINIMAL THUS FAR, WITH THE EXCEPTION OF THE  
PERSISTENT ST CLAIR RIVER JAM NORTH OF THE DETROIT AREA. THE COLD  
SNAP RESULTED IN A SUBSTANTIAL INCREASE OF ICE COVER ON THE GREAT  
LAKES. THERE WAS AN INCREASE FROM ONLY 15% 2 WEEKS AGO, UP TO  
AROUND 43% CURRENTLY.  
 
FROST DEPTH REMAINS SHALLOW ACROSS LOWER MICHIGAN AND SOUTHERN  
WISCONSIN, GENERALLY LESS THAN A FOOT. FROST WAS DEEPER OVER  
NORTHERN LOWER MICHIGAN, NORTHERN WISCONSIN, AND UP IN THE U.P.  
DEPTH OF 1 TO 2 FEET WAS REPORTED OVER THE MINNESOTA ARROWHEAD.  
THE COMBINATION OF DRIER SOILS AND SHALLOW FROST SHOULD ALLOW FOR  
MORE INFILTRATION OF WATER INTO THE GROUND AS THE SNOW MELTS, AND  
LESS RUNOFF INTO CREEKS AND RIVERS. THIS SUGGESTS A LOWER RISK FOR  
FLOODING IN THOSE AREAS.  
 
*********************  
HUDSON BAY DRAINAGE  
*********************  
   
..RED RIVER OF THE NORTH BASIN
 
 
OVERALL, THE RISK FOR FLOODING CONTINUES TO BE NORMAL TO BELOW NORMAL  
FOR SPRING 2021. IF FLOODING OCCURS, IT APPEARS THAT MAINLY MINOR  
FLOODING WILL BE THE RESULT.  
 
THE RED RIVER VALLEY REGION CONTINUES TO BE DRY, WITH LIMITED SNOW  
ON THE LANDSCAPE. SNOW DEPTH IS GENERALLY FROM 3 TO 10 INCHES THROUGH  
THE VALLEY. SOME SPOTS HAVE EVEN LESS. DEPTH IS A BIT HIGHER OVER THE  
TRIBUTARIES FEEDING IN FROM MINNESOTA, WHERE DEPTH UP TO 8-12 INCHES  
IS SEEN. MANY AREAS SAW A GOOD BAND OF SNOW ON TUESDAY, PROVIDING A  
GENERAL 2-6 INCHES. WATER CONTENT IN THE SNOW IS PRETTY SPARSE, WITH  
AN INCH OR LESS OF WATER FOR MOST AREAS. WHERE THE SNOW IS A BIT  
DEEPER OVER MINNESOTA, WATER CONTENT INCREASES UP CLOSER TO 2 INCHES.  
 
FROST DEPTH IS NEAR THE AVERAGE, WITH DEPTH GENERALLY BETWEEN 18  
AND 36 INCHES.  
 
WITH LIMITED WATER AVAILABLE, IT APPEARS THE RISK FOR FLOODING DUE  
TO MELTING SNOW THIS SPRING IS BELOW NORMAL. BUT SPRING RAINS ON TOP  
OF THE FROZEN GROUND AND WHAT RUNOFF WE GET, MOVING INTO FROZEN  
RIVERS, COULD LEAD TO SOME MINOR FLOODING.  
   
..SOURIS RIVER AND DEVILS LAKE BASINS
 
 
 
OVERALL, THE RISK FOR FLOODING IN THESE BASINS IS BELOW NORMAL.  
 
THESE AREAS HAVE ALSO BEEN DRY. SNOW COVER IS LIGHT ACROSS THE  
REGION, RANGING FROM JUST A FEW INCHES IN SOME SPOTS, UP TO 8 TO 12  
INCHES IN A FEW LOCATIONS. WATER CONTENT IN THAT SNOW IS GENERALLY  
LESS THAN AN INCH, BUT A FEW SPOTS COULD BE UP BETWEEN 1 AND 1.5  
INCHES.  
 
IN THE DEVILS LAKE BASIN, RUNOFF INTO THE LAKE LOOKS TO BE LESS THAN  
NORMAL THIS SPRING, OWING TO THE LIMITED SNOW AND WATER CURRENTLY  
OUT ON THE LANDSCAPE.  
 
FOR THE SOURIS BASIN, THE RISK FOR FLOODING IS ALSO LOW. RESERVOIRS  
UPSTREAM IN CANADA ARE BELOW NORMAL FOR THIS TIME OF YEAR, AND  
WITH DROUGHT CONDITIONS AND LOW SNOW COVER, THERE JUST ISN'T MUCH  
WATER AVAILABLE TO GENERATE MUCH OF A FLOODING RISK AT THIS POINT.  
 
**********************************  
UPPER MISSISSIPPI RIVER DRAINAGE  
**********************************  
 
OVERALL, FOR THE UPPER MISSISSIPPI RIVER DRAINAGE, THE RISK FOR  
FLOODING REMAINS THE SAME AS IT WAS 2 WEEKS AGO. THE RISK IS ABOUT  
AVERAGE ON THE WHOLE. OWING TO DRY CONDITIONS AND LIMITED SNOWPACK,  
THE HEADWATER BASINS HAVE A RISK THAT IS A LITTLE LESS THAN NORMAL.  
BUT FURTHER SOUTH, FROM IOWA INTO ILLINOIS AND WISCONSIN, THE RISK  
IS A LITTLE ABOVE NORMAL THANKS TO MORE MOIST SOIL CONDITIONS LAST  
FALL AND A SNOWPACK THAT CONTINUES TO BE IN THE TOP 10 FOR THIS  
TIME OF YEAR.  
 
SNOW COVER IS AVERAGE OR PERHAPS EVEN A BIT BELOW AVERAGE ACROSS  
THE HEADWATER AREAS. BUT IN THE BAND OF SNOW FROM EASTERN IOWA OVER  
ALONG THE ILLINOIS/WISCONSIN LINE, THERE IS AS MUCH AS 12 TO 18  
INCHES ON THE GROUND. WATER CONTENT IN THIS SNOW IS FROM 2 TO 4.5  
INCHES, WITH SOME AREAS UP TO AROUND 5 INCHES. THIS WATER EQUIVALENT  
IS IN THE TOP 10 HIGHEST FOR THIS TIME OF YEAR IN THAT AREA.  
 
THE COLD WEATHER TO START THE MONTH GENERATED MORE RIVER ICE, AND  
ALSO HELPED DRIVE THE FROST A BIT DEEPER INTO THE SOIL. BUT, FROST  
DEPTH OVERALL REMAINS LESS THAN NORMAL, WITH DEPTH MAINLY 12 TO 18  
INCHES OR LESS. ONLY THE HEADWATER AREAS ARE SEEING FROST CLOSER TO  
2 FEET. LESS FROST IN THE GROUND SUGGESTS THAT ONCE WE START GETTING  
MELT THIS SPRING, THERE WILL BE MORE THAT CAN INFILTRATE INTO THE  
SOIL, AND THUS LESS THAT RUNS OFF INTO WATERWAYS.  
 
ICE HAS THICKENED AND INCREASED FOR AREA CREEKS AND RIVERS, AND WE  
HAVE SEEN SOME MINOR ISSUES WITH ICE JAMMING AND DAMMING. ONCE WE  
START TO GET WARMER WEATHER LEADING TO MELT AND RISING WATER, WE  
WILL SEE JUST HOW MUCH IMPACT ICE BREAKUP WILL HAVE.  
 
LOOKING OUT THROUGH MARCH AND APRIL, THE LATEST OUTLOOKS CALL FOR  
TEMPERATURES TO GENERALLY RUN ABOVE NORMAL THROUGHOUT THE NCRFC  
SERVICE AREA. FOR PRECIPITATION, IT APPEARS VALUES WILL BE BELOW  
NORMAL FOR THE DAKOTAS INTO MINNESOTA, WITH ABOVE NORMAL  
PRECIPITATION FROM THE GREAT LAKES AREA SOUTH TOWARD ST LOUIS.  
 
SO, IN GENERAL, ANY FLOODING RISK CONTINUES TO LOOK NORMAL OR  
SLIGHTLY LESS THAN NORMAL FOR THE NORTHERN HEADWATER AREAS. THE  
HIGHEST LIKELIHOOD FOR FLOODING STILL LIES ALONG THE MISSISSIPPI  
RIVER DOWNSTREAM OF DAM 15, AS WELL AS TRIBUTARIES IN ILLINOIS AND  
EASTERN IOWA THAT FEED INTO THE MISSISSIPPI. THE RISK FOR FLOODING  
IN THESE AREAS IS ABOVE NORMAL. THE KEY FOR HOW MUCH FLOODING THERE  
WILL BE IN THOSE AREAS DEPENDS ON HOW QUICKLY THE SNOW MELTS, AND  
IF WE GET ANY SUBSTANTIAL RAINFALL.  
 
YOUR NORTH CENTRAL RIVER FORECAST CENTER WILL CONTINUE TO CLOSELY  
MONITOR THE SITUATION AS WE MOVE THROUGH FEBRUARY AND INTO MARCH.  
UPDATES TO OUR FLOOD POTENTIAL OUTLOOK INFORMATION WILL AGAIN BE  
PROVIDED THE LAST WEEK OF FEBRUARY. WE ALL KNOW THINGS WILL CHANGE  
OVER THE NEXT 4 TO 6 WEEKS, AND THOSE CHANGES WILL BE KEY IN JUST  
HOW THE FLOODING SITUATION WILL EVOLVE THIS SPRING.  
 

 
 
MW  
 

 
NNNN  
 
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