Spring flood threat quiet here for now
Outlook shows below normal risk despite recent snows
The National Weather Service early spring river outlook for the St. Croix Valley calls for a below normal flood risk.
Of course, that could change depending on the amount of moisture the area receives later in the spring, according to NWS Hydrologist Diane Cooper.
And that unknown led Cooper to remind Valley residents living in flood-prone areas and who have flood insurance to renew those flood insurance policies now in the event the NWS flood outlook changes in the weeks ahead.
“Who knows what Mother Nature can bring about,” she said. “People need to maintain their flood insurance.”
Cooper said current data indicates a below normal flood risk on the Mississippi River south of St. Paul. That is important because high water in the Mississippi backs up the St. Croix River, leading to local flooding.
“For you in Stillwater to flood, it’s really that backwater from the Mississippi. To flood on the St. Croix, you have to be flooding on the Mississippi,” Cooper said. “St. Paul and Hastings are two areas you are going to look at and right now they’re below normal.”
The NWS March 7 spring outlook for river conditions said two areas facing normal risks for flooding are the upper Minnesota and Mississippi river basins.
“With the snowfall in February, conditions have changed from below normal with the January outlook to a normal risk of flooding with the February outlooks,” said the NWS website.
Areas mentioned on the NWS website for a normal flood risk are Montevideo and Granite Falls on the Minnesota River; Redwood Falls on the Redwood River; New Ulm on the Cottonwood River; Long Prairie on the Long Prairie River and St. Cloud on the Sauk and Mississippi rivers.
The NWS flood outlook also calls for a risk of flooding in southern and southeastern Minnesota and west-central Wisconsin due to concrete frost, which is frost on and just below the soil surface. Concrete frost could lead to creek and stream flooding from snowmelt runoff.
Cooper said the concrete frost area is just south of Washington County. She added that area has not seen consistent snow cover this winter.
Cooper also said some areas of the Valley might not completely escape spring flooding, depending on how much moisture the area gets in the coming weeks.
“That doesn’t mean that parts of Washington County and St. Croix County in Wisconsin couldn’t see localized flooding,” she said. “The snowpack is more consistent in that area.”
One factor affecting the spring outlook that is an unknown now is spring rain, Cooper said. The Mississippi River in St. Paul currently has “decent capacity” to handle a rise in the river from heavy rain.
“It’s going to take a really heavy rain event” to cause high water on the Mississippi and St. Croix rivers, she said.
Because rain events happen quickly, Cooper said it’s important for property owners with flood insurance to renew those policies now because of the 30-day waiting period before policies go into effect.
“With a rain-induced event, you don’t have that time. The flooding in Duluth last year is a reminder that flooding can happen any time.”
Visit the National Weather Service website at www.crh.noaa.gov/mpx and click on “Spring Outlook for River Conditions” for updates and to view forecast maps.