OTTUMWA — Southeast Iowa is facing another round of weekend snow, but this isn’t expected to be anywhere near as bad as the past two storms.
This will be the third time in about a week the area will receive accumulating snow. A snowstorm last Friday and Saturday brought a couple inches, and a much bigger storm Tuesday dropped 6.5 inches of snow on Ottumwa.
Forecasters are only expecting an inch or two of new snow from this storm. It’s enough to be a headache if you have to drive anywhere but not enough to bring the area to a halt. This system does have one unwelcome echo of Tuesday’s storm, though: It will be followed by bitter cold. Sunday night’s low is expected to be about -9, with Monday’s high reaching only 7 degrees.
The winter is on pace to set a new mark for the most days with subzero temperatures this century. State Climatologist Harry Hillaker said the 30-year average for Ottumwa is 12.6 days per winter with subzero lows. This winter has already had 23 days with those temperatures.
The most recent year with more was the winter of 2000-01, when there were 25 days with subzero lows. It’s not guaranteed, but it doesn’t take much imagination to see this year topping that mark.
All that cold weather has the potential to cause some serious problems. Water mains are laid deeper than the frost usually reaches, but frozen soil is going deeper now than it has for a very long time. Hillaker said the frost depth in the Ottumwa area is between 20-30 inches, “which is quite a bit for this point. At any time in winter, really.”
And that’s the depth for turf-covered soil. Pavement has different insulation properties. The closest Iowa Department of Transportation measurement is near Sigourney, and it’s reading a 32-degree temperature at 48 inches.
Ottumwa Water and Hydro Director Mike Heffernan said his crews are seeing frost down to about 3 feet. That’s not enough to threaten the city’s water mains, which are buried at an average of 4 or 5 feet.
“It really hasn’t caused us too much trouble yet, but it is causing some homeowners problems with their service lines,” he said.
The service lines branch off the water mains, supplying water to the individual residences or businesses. That means they have to cross through the frozen soil, raising their risk of freezing.
That’s not to say Heffernan isn’t keeping a close eye as the frost moves deeper.
“We’re definitely watching that,” he said. “It’s obviously a concern.”