NWS: St. Croix River under ‘normal’ flood risk

Although the St. Croix River in Stillwater is forecast to have a normal risk of flooding, a cold March and slow snow melt likely mean little chance of major flood issues, according to the National Weather Service.

The March 29 spring flood outlook update added the St. Croix River and the Mississippi River in St. Paul and Hastings to its list of areas with a normal risk of flooding. The only areas in Minnesota forecast for an above normal river flood risk are the Minnesota River in Montevideo; Long Prairie River in Long Prairie, and Mississippi River in St. Cloud.

NWS Hydrologist Diane Cooper said that although the St. Croix was included in the normal risk of flooding list, forecast are not concerned about the potential for major flooding from the river.

“It means for the period, at this point in time, we’re not looking at an above normal flood risk,” she said.

That outlook comes despite normal to above normal precipitation from December through March that produced snow pack of 1.5 to 2 feet in areas of the upper Minnesota and Mississippi river valleys, according to the NWS. Although the NWS does not keep track of snow melt, Cooper said melting snow in much of the state expect in the northeast and northwest portions plays a major role in Mississippi River’s spring rise.

While the Twin Cities has seen snow melt, parts of western Minnesota have not seen much snow melt, leaving a moisture-laden snowpack “ripe” to release water, Cooper said.

“We don’t see much water movement in the upper Mississippi and upper Minnesota (rivers),” she said.

The main reason is an unsually cold start to spring in the state. The NWS said Tuesday that last month was the coldest March in 11 years. Temperatures were 5 to 10 degrees below normal and snowfall in most areas was six to 12 inches above normal. Parts of the state were hit with by two big snowstorms March 4-5 and March 15. Only southwest Minnesota had below normal precipitation.

“After having a March in 2012 that had temperatures that belonged more in April, this March went in the other direction as persistent cold air in the Twin Cities, St. Cloud and Eau Claire, Wis., all having their coldest March since 2002,” the NWS said.

Cooler-than-normal temperatures returned to the St. Croix Valley Monday and Tuesday with highs in the middle to high 30s. However, the midweek forecast calls for highs in the low 50s today and Thursday before temperatures fall to the middle to upper 40s Friday and Saturday. There is a slight chance of rain and snow late Wednesday into Thursday and again Friday with rain and snow likely Friday night and Saturday.

“Right now, we don’t have a significant concern,” Cooper said about flooding from snow melt.

However, Cooper urged St. Croix Valley residents living in flood-prone areas to consider buying flood insurance or renewing existing policies. Flood insurance has a 30-day waiting period after purchase before going into effect.

“We would urge people to flood insurance like homeowner’s insurance. You don’t want to let that protection lapse,” she said.

The reason, according to Cooper, is that heavy rainfall in a short period of time in the Mississippi River basin can cause flooding on the St. Croix from high water on the Mississippi backing up into the St. Croix.

“Rain is so much more of a variable event than snowmelt,” she said, adding the the St. Croix River did not see high water in 2012 until mid-spring.
“Our high water (in 2012) was not due to snowmelt. It was due to rain in May,” she said.