Flood outlook lowers threat on tributary rivers but remains high for the Mississippi

CEDAR RAPIDS, Iowa (KCRG) - The National Weather Service released its third and final scheduled spring flood outlook of the season on Thursday. The odds of higher-end flooding on the Mississippi have come down compared to the previous outlook, but remain much higher than the historical chances. The chances of spring flooding on the tributary rivers have lowered, too. You can see the current odds of minor, moderate, and major flood stage compared to historical odds below, along with how they compare to the previous outlook’s odds.

Snowpack: The snowpack over the Mississippi River basin has been melting. But, as much as three to six inches of water is in the remaining snowpack over portions of Minnesota and Wisconsin. Locally, the snowpack is virtually gone, and so won’t be a factor for tributary rivers.

Soil moisture: Soil moisture – the amount of water currently in the soil – remains very high, despite a period of dry weather in February and early March. This means the ground can't absorb as much snowmelt and rainfall.

Streamflow:: Streamflow is how much water is already flowing through the rivers at this time. Streamflow is running near normal to high, so it won’t take as much new water coming into a river to cause flooding.

Frost depth:Frost is not unusually deep across much of the area. Deeply frozen ground causes snowmelt and rain to run straight into the streams and rivers without absorbing much. This is not a significant factor this year.

This outlook for spring flooding (through May), and doesn’t necessarily mean anything about the risk of summertime flooding. While spring flooding can make it easier for flooding to happen in the summer, that is not always what happens.

Below are the flood chances for the river forecast locations for our local basins, compared to the historical average as well the previous outlook. It compares the odds for reaching minor, moderate, and major flood stage.

Mississippi River

Lansing:
Minor – 31% (previous: 84%, average: 10%)
Moderate – 10% (previous: 49%, average: 8%)
Major – 8% (previous: 36%, average: less than 5%)

McGregor:
Minor – Greater than 95% (previous: greater than 95%, average: 52%)
Moderate – 66% (previous: greater than 95%, average: 28%)
Major – 31% (previous: 82%, average: 9%)

Guttenberg:
Minor – Greater than 95% (previous: greater than 95%, average: 45%)
Moderate – 50% (previous: 90%, average: 14%)
Major – 13% (previous: 52%, average: 5%)

Dubuque:
Minor – Greater than 95% (previous: greater than 95%, average: 51%)
Moderate – Greater than 95% (previous: greater than 95%, average: 43%)
Major – 51% (previous: 90%, average: 13%)

Bellevue:
Minor – 82% (previous: greater than 95%, average: 33%)
Moderate – 65% (previous: greater than 95%, average: 26%)
Major – 34% (previous: 85%, average: 11%)

Cedar River

Charles City:
Minor – 11% (previous: 31%, average: 19%)
Moderate – 6% (previous: 18%, average: 10%)
Major – Less than 5% (previous: 7%, average: 6%)

Janesville:
Minor – 6% (previous: 8%, average: 9%)
Moderate – Less than 5% (previous: less than 5%, average: less than 5%)
Major – Less than 5% (previous: less than 5%, average: less than 5%)

Cedar Falls:
Minor – 41% (previous: 72%, average: 44%)
Moderate – 9% (previous: 25%, average: 18%)
Major: Less than 5% (previous: 9%, average: 10%)

Waterloo:
Minor – 17% (previous: 38%, average: 31%)
Moderate – Less than 5% (previous: 5%, average: 6%)
Major – Less than 5% (previous: less than 5%, average: less than 5%)

Vinton:
Minor – 8% (previous: 22%, average: 19%)
Moderate – Less than 5% (previous: 6%, average: 7%)
Major – Less than 5% (previous: 5%, average: less than 5%)

Palo:
Minor – 9% (previous: 23%, average: 22%)
Moderate – Less than 5% (previous: 6%, average: 7%)
Major – Less than 5% (previous: less than 5%, average: less than 5%)

Cedar Rapids:
Minor – 13% (previous: 28%, average: 28%)
Moderate – 7% (previous: 21%, average: 15%)
Major – Less than 5% (previous: 9%, average: 8%)

Cedar Bluff:
Minor – 28% (previous: 28%, average: 31%)
Moderate – 9% (previous: 9%, average: less than 5%)
Major – Less than 5% (previous: less than 5%, average: less than 5%)

Conesville:
Minor – Greater than 95% (previous: 77%, average: 56%)
Moderate – 10% (previous: 23%, average: 26%)
Major – Less than 5% (previous: 9%, average: 8%)

Iowa River

Marshalltown:
Minor – 6% (previous: 8%, average: 9%)
Moderate – Less than 5% (previous: less than 5%, average: less than 5%)
Major – Less than 5% (previous: less than 5%, average: less than 5%)

Tama:
Minor – 18% (previous: 22%, average: 24%)
Moderate – 8% (previous: 16%, average: 14%)
Major – Less than 5% (previous: less than 5%, average: less than 5%)

Marengo:
Minor –75% (previous: 78%, average: 68%)
Moderate – 45% (previous: 52%, average: 52%)
Major – Less than 5% (previous: 5%, average: 6%)

Iowa City:
Minor – Less than 5% (previous: less than 5%, average: 6%)
Moderate – Less than 5% (previous: less than 5%, average: less than 5%)
Major – Less than 5% (previous: less than 5%, average: less than 5%)

Lone Tree:
Minor – 8% (previous: 10%, average: 13%)
Moderate – Less than 5% (previous: less than 5%, average: 7%)
Major – Less than 5% (previous: less than 5%, average: less than 5%)

Columbus Junction:
Minor – 6% (previous: 16%, average: 13%)
Moderate – Less than 5% (previous: 8%, average: 5%)
Major – Less than 5% (previous: less than 5%, average: less than 5%)

Wapsipinicon River

Independence:
Minor – 8% (previous: 14%, average: 8%)
Moderate – 7% (previous: 8%, average: 7%)
Major – 5% (previous: 6%, average: less than 5%)

Anamosa:
Minor – 24% (previous: 27%, average: 26%)
Moderate – 9% (previous: 13%, average: 10%)
Major – Less than 5% (previous: less than 5%, average: less than 5%)

English River

Kalona:
Minor – 52% (previous: 52%, average: 50%)
Moderate – 21% (previous: 34%, average: 32%)
Major – 8% (previous: 9%, average: 12%)

Skunk River

Sigourney:
Minor – 49% (previous: 55%, average: 57%)
Moderate – 35% (previous: 35%, average: 43%)
Major – 5% (previous: 6%, average: 11%)

Oskaloosa:
Minor – Less than 5% (previous: less than 5%, average: less than 5%)
Moderate – Less than 5% (previous: less than 5%, average: less than 5%)
Major – Less than 5% (previous: less than 5%, average: less than 5%)

Maquoketa River

Manchester:
Minor – 19% (previous: 19%, average: 22%)
Moderate – 14% (previous: 13%, average: 16%)
Major – 8% (previous: 8%, average: 8%)

Maquoketa:
Minor – 10% (previous: 16%, average: 11%)
Moderate – 6% (previous: 5%, average: 9%)
Major – Less than 5% (previous: less than 5%, average: 6%)

Turkey River

Elkader:
Minor – 30% (previous: 82%, average: 35%)
Moderate – 11% (previous: 42%, average: 13%)
Major – Less than 5% (previous: 17%, average: less than 5%)

Garber:
Minor – 22% (previous: 54%, average: 27%)
Moderate – 11% (previous: 28%, average: 15%)
Major – 9% (previous: 20%, average: 7%)

Upper Iowa River

Decorah:
Minor – Less than 5% (previous: less than 5%, average: less than 5%)
Moderate – Less than 5% (previous: less than 5%, average: less than 5%)
Major – Less than 5% (previous: less than 5%, average: less than 5%)

Dorchester:
Minor – 14% (previous: 37%, average: 17%)
Moderate – 8% (previous: 12%, average: 6%)
Major – 7% (previous: 11%, average: less than 5%)