NWS calls for slight chance of spring flooding
Published 8:20 am Friday, January 28, 2011
The National Weather Service’s first spring flood forecast says all four major flooding factors are “above normal” in the Austin area, meaning there’s a slight risk of flooding.
Of the four factors, which include stream flow, snow pack, frost depth and soil moisture, the stream flow is currently the issue for the Cedar River.
The stream flow can increase in the spring if the ground frost persists, causing water to run into lowlands instead of soaking in. As of now, the upper Cedar River stands a 6 percent chance of reaching the flood stage this spring.
However, Hydrologist Jeff Zogg at the NWS in Des Moines said it might be too early to tell.
“We have a lot of winter to go yet. Things can change a lot.”
The NWS does three flood forecasts each spring to continually update its accuracy. It predicts the potential outcomes by plugging in the four factors and assuming temperatures will rise at the normal rate for spring.
The snow pack could also be a problem this year, but Zogg said there’s been previous years with more snow pack that didn’t cause floods. And if the weather warms up slowly, the risk of flooding decreases.
Zogg was not worried about major floods for the Cedar at this point.He said they’ll have to wait until March to have a better idea of increasing temperatures and the thaw. Right now, all they are predicting is a cooler February than average.
The forecasts are primarily a heads up, Zogg added.
On the other hand, rivers such as the St. Croix, Mississippi and Minnesota have a 90 percent chance of flooding lowlands, roadways and bridges in the Twin Cities metro area, according to the Twin Cities NWS.
For more information on flood forecasts, visit www.weather.gov.