Don’t start filling sandbags yet, but the experts say Iowa’s facing an above-normal risk for snowmelt flooding this spring. Jeff Johnson, a meteorologist at the National Weather Service, says parts of northern Iowa have a foot or more of packed snow on the ground with six-to-ten inches across much of central Iowa.
Some areas in north-central Iowa have 16-inches of snowpack — or more. Johnson says that’s very deep. "We’re running about eight-to-12 inches above normal across northern Iowa for snowpack," Johnson says. "How that relates to liquid equivalent is about two-to-four inches of water equivalent snowpack in reserve up there, sitting there ready to melt."
Iowa still faces two more months of winter and Johnson says those two months will be key in determining the fate of a potential repeat of last year’s historic flooding. "There is a risk of springtime snowmelt flooding and as we all know, that really is going to be dependent on how the snowpack melts," Johnson says. "If it melts in a positive way, a little at a time with a prolonged period of dry weather, it would just relieve itself. On the other extreme, if we dumped heavy amounts of rain on top of the snowpack and had a rapid melt, then we’re going to have problems."
He says the soil moisture levels across much of Iowa are above normal and still haven’t recovered from last summer. Spring arrives in about eight weeks — on March 20th — and he says Iowans will just have to sit tight and see how the risk of repeated flooding plays out.
"I’ve seen years where we’ve had more snow than this and we’ve had the proper melting conditions and we really didn’t face any problems at all," Johnson says. "On the other extreme, I’ve seen it where we’ve had very little snowpack in January and you get into a very snowy pattern in February and March, you get a big snowpack and then you melt it off quickly."
Last year’s June flooding forced thousands of Iowans to evacuate from their homes in nine counties. Statewide, flood damage was estimated at $10-billion.