SNOWMELT FLOOD OUTLOOK
NATIONAL WEATHER SERVICE
MISSOURI BASIN RIVER FORECAST CENTER
PLEASANT HILL, MO
MAR 23, 2006
THIS SNOWMELT OUTLOOK IS FOR THE MISSOURI RIVER DRAINAGE WHICH
INCLUDES RIVERS IN MONTANA, WYOMING, COLORADO, NORTH AND SOUTH
DAKOTA, NEBRASKA, KANSAS, IOWA, AND MISSOURI.
SNOWMELT FLOOD OUTLOOK
THIS PAST WEEKEND THE CENTRAL PLAINS WAS HIT BY A FAIRLY MAJOR LATE
WINTER SNOWSTORM. MANY LOCATIONS IN NEBRASKA REPORTED RECORD SNOWFALL
AMOUNTS FOR THAT DATE IN MARCH. AS A RESULT, THERE IS SUBSTANTIAL
SNOW ON THE GROUND IN MUCH OF THE EASTERN TWO-THIRDS OF NEBRASKA.
ADDITIONALLY, THIS STORM PRODUCED A BAND OF SNOW FROM EASTERN COLORADO
THROUGH WESTERN IOWA. EVEN THOUGH THIS SNOW REMAINS ON THE GROUND AFTER
THE WEEKEND STORM, THERE IS LITTLE POTENTIAL FOR FLOODING DUE TO ITS
MELTING. THIS IS TRUE EVEN IF NORMAL PRECIPITATION FOR THE NEXT TWO
WEEKS IS ADDED TO THE CURRENT SNOW CONDITIONS. THE ONLY EXCEPTIONS TO
THIS ARE ON THE LITTLE SIOUX, ROCK AND BIG SIOUX RIVERS IN IOWA AND
SOUTH DAKOTA AND THE LOWER PLATTE AND GRAND RIVERS IN MISSOURI. THERE
IS A POSSIBILITY FOR MINOR, AND ISOLATED MODERATE, FLOODING IN THESE
AREAS IF NORMAL PRECIPITATION OCCURS THIS SPRING.
BASED ON THE CURRENT SNOWPACK IN THE MOUNTAINS OF MONTANA, WYOMING
AND COLORADO, THERE IS A CHANCE FOR MINOR FLOODING ON THE SUN AND BIG
HOLE RIVERS OF MONTANA. ALTHOUGH THE SNOWPACK IN COLORADO IS ABOVE
AVERAGE, THERE IS CURRENTLY NO FLOODING FORECAST THERE.
THIS OUTLOOK CONTAINS A GENERALIZED SUMMARY OF SNOWMELT FLOOD
POTENTIAL. ABOVE NORMAL FUTURE SNOW ACCUMULATIONS COMBINED WITH
HEAVY RAINS AND RAPID MELT WILL INCREASE THE CURRENT FLOOD POTENTIAL
WHILE BELOW NORMAL FUTURE PRECIPITATION AND GRADUAL OR INTERMITTENT
FREEZING AND THAWING WILL DECREASE THE MAGNITUDE OF THE CURRENT
ASSESSMENT. IN ADDITION, WHEN MANY OF THE FROZEN RIVERS AND STREAMS
THAW, ICE JAMS CAN OCCUR CAUSING HIGHER RIVER LEVELS AND POSSIBLE
FLOODING.
THESE PROJECTIONS OF RIVER STAGES AND RESERVOIR LEVELS ARE BASED
ON CURRENT OBSERVED STATES OF STREAMFLOW, SOIL MOISTURE, AND SNOW
PACK, COUPLED WITH FUTURE PRECIPITATION AND TEMPERATURE PATTERNS
AND ANTICIPATED OPERATIONAL HYDROLOGIC CHANGES SUCH AS RESERVOIR
RELEASES AND CANAL DIVERSIONS. "OUTLOOKS" ARE PROVIDED FOR
LONG-RANGE (WEEKS TO MONTHS) PROJECTIONS BASED ON CLIMATOLOGICAL
PATTERNS OF PRECIPITATION AND TEMPERATURE. "FORECASTS" ARE PROVIDED
FOR SHORT-TERM (DAYS) PROJECTIONS BASED ON FUTURE FORECASTED
PATTERNS OF PRECIPITATION AND TEMPERATURE. THE UNCERTAINTY OF THESE
PRODUCTS VARIES FROM SEASON TO SEASON AND SITE TO SITE. IN RECENT
YEARS, OUTLOOK CRESTS HAVE BEEN ABOVE THE OBSERVED CREST ABOUT AS
OFTEN AS THEY HAVE BEEN BELOW THE OBSERVED CREST. THE UNCERTAINTY
OF FORECASTS TEND TO BE LESS THAN THE UNCERTAINTY OF OUTLOOKS DUE TO
THEIR SHORTER LEAD TIME. USERS OF THESE PRODUCTS ARE ENCOURAGED TO
CONTACT THEIR NEAREST NATIONAL WEATHER SERVICE FORECAST OFFICE FOR
CONTINUED UPDATES OF METEOROLOGICAL CONDITIONS WHICH CAN HAVE
SIGNIFICANT IMPACTS ON FLOOD PLANNING AND FLOOD FIGHTING ACTIVITIES.
BECAUSE NO FLOODING IS EXPECTED AT LOCATIONS NOT REPRESENTED BY AHPS
PRODUCTS, NO OUTLOOK NUMBERS ARE BEING ISSUED WITH THIS TEXT PRODUCT.
PLEASE REFER TO AHPS PRODUCTS FOR INFORMATION ABOUT LOCATIONS WHERE
POTENTIAL FLOODING IS FORECAST.
IT IS LIKELY THAT THIS WILL BE THE LAST SPRING SNOWMELT OUTLOOK OF
THE SEASON. HOWEVER, IF CONDITIONS WARRANT, AN OUTLOOK COULD BE ISSUED
ON THURSDAY, APRIL 6. RIVER INFORMATION CAN BE FOUND IN THE DAILY
HYDROLOGIC ACTIVITIES DISCUSSION, FLOOD FORECASTS FOR RIVERS NEAR OR
ABOVE FLOOD STAGE, DAILY MISSOURI RIVER FORECASTS, AHPS PRODUCTS AND
THE MONTHLY WATER SUPPLY OUTLOOK, ALL ISSUED BY THIS OFFICE.
CURRENT SNOW CONDITIONS
NEBRASKA
PRIOR TO THIS PAST WEEKEND'S SNOWSTORM, MUCH OF CENTRAL NEBRASKA HAD
NOT RECEIVED APPRECIABLE PRECIPITATION IN OVER TWO MONTHS. SNOW DEPTH
REPORTS THIS WEEK RANGED ALL THE WAY UP TO 30 INCHES IN EAST CENTRAL
NEBRASKA NEAR ORD. MUCH OF THE STATE WAS COVERED BY A MINIMUM OF 8-9
INCHES, WITH THE HEAVIEST SNOWS ORIENTED IN A SOUTHWEST-NORTHEAST BAND
STARTING AT THE COLORADO BORDER. THE SNOW THAT FELL IN THIS STORM
PRODUCED WATER EQUIVALENT AMOUNTS IN MOST PLACES WITH A RATIO OF ABOUT
10:1. WATER EQUIVALENT AMOUNTS IN CENTRAL NEBRASKA ARE APPROXIMATED TO
BE TWO TO TWO AND A HALF INCHES. ELSEWHERE IN THE STATE, WATER
EQUIVALENTS RANGE FROM THREE QUARTERS OF AN INCH TO AN INCH AND A HALF.
KANSAS
THE NORTHERN TIER OF KANSAS, WEST OF TOPEKA, RECEIVED MODERATE SNOWFALL
AMOUNTS WITH THIS PAST WEEKEND'S STORMS. AVERAGE REPORTED AMOUNTS
INDICATED SIX TO EIGHT INCHES OF SNOW ON THE GROUND. THERE WERE SEVERAL
REPORTS OF FOOT DEEP AMOUNTS THOUGH, ESPECIALLY ALONG THE NEBRASKA
BORDER IN THE CENTER OF THE STATE. SNOW WATER EQUIVALENTS IN THIS AREA
WERE GENERALLY THREE-QUARTERS OF AN INCH TO AN INCH, WITH SOME MODEL
ESTIMATIONS UP TO ONE AND A QUARTER INCHES.
SOUTH DAKOTA
THE NORTHEASTERN PART OF THE STATE IS REPORTING VERY LITTLE SNOW. THE
SOUTHERN HALF OF THE STATE RECEIVED THE BRUNT OF THE RECENT SNOWSTORM
IN SOUTH DAKOTA. SNOW DEPTHS UP TO 18 INCHES WERE REPORTED IN A FEW
LOCATIONS, HOWEVER, AN AVERAGE DEPTH FOR THIS AREA IS PROBABLY NINE
TO ELEVEN INCHES. THE NORTHERN PART OF THE STATE, WEST OF GETTYSBURG,
AVERAGES SLIGHTLY LESS SNOW ON THE GROUND, ABOUT FIVE TO SEVEN INCHES.
MAXIMUM SNOW WATER EQUIVALENTS, OUTSIDE OF THE BLACK HILLS, ARE
ASSOCIATED WITH THE HEAVIER SNOWS IN THE SOUTHERN PART OF THE STATE AND
RANGE FROM ONE TO ONE AND THREE-QUARTERS OF AN INCH.
WYOMING, MONTANA AND NORTH DAKOTA
THE STORM THIS PAST WEEKEND PRODUCED ONLY MINOR SNOWFALL IN PLAINS
AREAS OF THESE STATES. CURRENT SNOW WATER EQUIVALENTS RARELY EXCEED ONE
QUARTER OF AN INCH. THE ONLY EXCEPTION TO THIS GENERALIZATION WOULD BE
CENTRAL NORTH DAKOTA WHERE EQUIVALENTS MAY RANGE UP TO THREE-QUARTERS
OF AN INCH.
COLORADO AND IOWA
BEING NEAR THE EDGES OF THE WEEKEND'S SNOW, SNOW DEPTHS IN COLORADO AND
IOWA AVERAGE FOUR TO SIX INCHES. WITHIN MBRFC'S BOUNDARIES, PLAINS SNOW
WATER EQUIVALENTS RARELY EXCEED ONE HALF OF AN INCH.
EASTERN KANSAS AND MISSOURI
THE MAJORITY OF THE PAST WEEKEND'S PRECIPITATION IN THESE AREAS FELL AS
RAIN. MINOR SNOW AMOUNTS ARE ON THE GROUND IN FAR NORTHEASTERN KANSAS
AND NORTHERN MISSOURI. MOST OF THIS SNOW SHOULD BE MELTED IN THE NEXT
FEW DAYS AS TEMPERATURES ARE EXPECTED TO MOVE CLOSER TO SPRINGTIME
NORMALS.
BASIN SNOWPACK IN THE MOUNTAINS OF SOUTHERN WYOMING, MONTANA AND COLORADO
GENERALLY RANGES FROM ABOUT 100% TO 110% OF AVERAGE. THERE IS LESS
SNOWPACK IN THE MOUNTAINS OF NORTHERN WYOMING AND THE BLACK HILLS, WHERE
THE SNOWPACK IS ABOUT 80 TO 90% OF AVERAGE.
CURRENT SOIL MOISTURE CONDITIONS
THE MAJORITY OF THE WESTERN TWO-THIRDS OF THE BASIN WAS DRIER THAN
NORMAL PRIOR TO THIS RECENT EVENT. AS THE SNOW MELTS, IT SHOULD PROVIDE
THE AREA WITH SOME MUCH NEEDED SOIL MOISTURE. SINCE LAST WEEKEND'S EVENT
WAS MOSTLY A RAIN EVENT IN MISSOURI AND EASTERN KANSAS, SURFACE SOILS
IN THIS AREA SHOULD BE CLOSE TO SATURATED. OVER THE COURSE OF THE LAST
FEW WEEKS, EASTERN SOUTH DAKOTA AND NEBRASKA AND WESTERN IOWA RECEIVED
PRECIPITATION. THESE EVENTS HAVE LIKELY SATURATED THE SOILS IN THIS
AREA.
CURRENT RIVER CONDITIONS
MANY RIVERS IN THE NORTHERN PART OF THE BASIN REMAIN ICED OVER. RIVER
LEVELS, ESPECIALLY IN THE SOUTHERN TWO THIRDS OF THE BASIN, ARE BELOW
NORMAL. SOME RIVERS IN THE NORTHEASTERN PORTION OF THE BASIN HAVE LEVELS
ABOVE NORMAL FOR THIS TIME OF YEAR, WHICH IS LARGELY A RESULT OF SOME
SLIGHTLY ABOVE NORMAL PRECIPITATION IN THE REGION DURING EARLY WINTER.
A SUMMARY OF RIVER CONDITIONS FOR SELECTED RIVER STATIONS ON
MARCH 22 FOLLOWS:
LONG TERM CURRENT
MEDIAN(CFS) (CFS)
JAMES RIVER - HURON, SD 115 670
BIG SIOUX RIVER - AKRON, IA 1400 1375(est)
PLATTE RIVER - LOUISVILLE, NE 8460 3360
KANSAS RIVER - DESOTO, KS 3850 2775
GASCONADE RIVER - JEROME, MO 2000 1720
MISSOURI RIVER - OMAHA, NE 31000 20600
MISSOURI RIVER - RULO, NE 38700 22400
MISSOURI RIVER - ST. JOSEPH, MO 37900 20700
MISSOURI RIVER - WAVERLY, MO 44000 23600
MISSOURI RIVER - HERMANN, MO 78700 33000
END MBRFC