HYDROLOGIC OUTLOOK

NATIONAL WEATHER SERVICE OMAHA/VALLEY NE

1121 AM CDT MON JUN 6 2011 

…SIGNIFICANT AND PROLONGED FLOODING LIKELY ALONG THE MISSOURI RIVER…

 IN THE PAST FEW WEEKS…THE UPPER MISSOURI BASIN HAS RECEIVED NEARLY A YEAR’S WORTH OF RAINFALL. IN ADDITION…SNOW PACK RUNOFF YET TO FULLY ENTER THE UPPER PORTION OF THE RIVER SYSTEM IS 140 PERCENT OF NORMAL. THESE CONDITIONS ARE RESULTING IN MISSOURI BASIN RESERVOIRS ACROSS EASTERN MONTANA AND THE DAKOTAS NEARING THEIR MAXIMUM LEVELS.

RECORD RELEASES HAVE BEGUN AT GAVINS POINT DAM LOCATED TO THE WEST OF YANKTON SOUTH DAKOTA. CURRENT RELEASES ARE AROUND 100,000 CFS (CUBIC FEET PER SECOND)…AND WILL BE INCREMENTALLY INCREASED TO 150,000 CFS BY MID-JUNE. THE PREVIOUS HIGH RELEASE AT GAVINS POINT WAS 70,000 CFS IN 1997.

 THESE EXTREMELY HIGH FLOWS…COMBINED WITH NORMAL RAINFALL…MAY RESULT IN NEAR-RECORD FLOODING ALONG PORTIONS OF THE MISSOURI RIVER. IN ADDITION…MANY LOCATIONS ON THE MISSOURI RIVER WILL REMAIN FLOODED THROUGH JULY.

 THE FOLLOWING TABLE IS THE LONG-RANGE MISSOURI RIVER FORECAST…

ASSUMING NORMAL SUMMER PRECIPITATION ALONG WITH THE EXPECTED PEAK RELEASES OF 150,000 CFS FROM GAVINS POINT DAM. RECORD AND 2010 FLOOD CRESTS HAVE BEEN INCLUDED FOR REFERENCE. THIS PRODUCT WILL BE UPDATED FREQUENTLY AS THE LONG-RANGE FORECAST WILL LIKELY BE MODIFIED AS A RESULT OF RAINFALL EVENTS AND POTENTIAL ADJUSTMENTS TO RELEASES AT GAVINS POINT.

 LOCATION FS LONG-RNG FORECAST(FT) RECORD(FT) 2010 CREST(FT)

——– — ——————— ———- ————–

SIOUX CITY 30 35 TO 37 44.28-1952 25.49

DECATUR 35 40 TO 42 32.31-1996 31.42

BLAIR 26.5 30 TO 32 33.50-1952 26.93

OMAHA 29 34 TO 36 40.20-1952 28.74

NEB. CITY 18 27 TO ABOVE 28* 27.66-1952 25.21

BROWNVILLE 33 43 TO ABOVE 44* 44.30-1993 42.89

RULO 17 25.5 TO ABOVE 27* 26.63-2010 26.63

——– — ——————— ———- ————–