The Ottumwa Courier

October 27, 2012

Winter forecast a toss-up

Any precipitation an improvement on continuing Iowa drought, climatologist says

CHELSEA DAVIS
Courier Staff Writer

OTTUMWA — A warmer, drier winter would mean less money spent on snow removal. On the other hand, a colder, wetter winter would help Iowa recover from the summer’s drought, Iowa’s climatologist said.

The National Weather Service’s winter outlook slightly favors a warmer and drier winter than normal for Iowa’s mid-winter months (December, January and February), said state climatologist Harry Hillaker.

“But there really aren’t any strong indications one way or the other,” he said. “The main impetus in that outlook was the expectation that there was going to be an El Nino event developing in the Pacific Ocean.”

Historically, he said, when that happens there’s a higher chance for a warmer, drier mid-winter season.

“However, the El Nino event has been trying to develop since April this year, and it hasn’t quite gotten there yet,” he said. “So I’m not putting a whole lot of stock in that outlook.”

As far as Iowa’s continuing drought, that’s more complicated, Hillaker said.

“Chances are the drought is not going to get any worse, even if the outlook is true,” he said. “The reason for that is at this time of year, evaporation rates — because things will dry out further — are down to almost zero.”

So any precipitation Iowa sees is going to improve things, at least to an extent, he said.

“In mid-summer when it’s in the 90s, if you don’t get rain for a few days, vegetation is transpiring and ponds are evaporating,” he said. “This time of year there’s nothing growing so you don’t have vegetation pulling moisture out of the ground.”

Chances are the drought will lessen as time goes on, he said, due to the lack of evaporation.

“The dry winter forecast, even if it does happen, isn’t maybe as bad as it sounds,” he said.

And a dry forecast means a better bottom line for the city of Ottumwa. In a previous interview with the Courier, city Finance Director Bob Jay said for the winter of 2011-12, the city had budgeted $300,000 for snow removal and only ended up spending $120,000.

Just in case, though, the city budgeted $317,000 for this winter based on averages from a period of several years.

“We normally budget for what we see in a trend over several years,” Jay said. “If it’s worse, we’ll have to come up with the money somewhere else in the fund. If it’s less, the money stays in the fund and rolls over to next year.”

Wapello County’s budget was helped as well, since they have leftover unused salt and sand from last year’s mild winter.

Fall has not been particularly wet so far, Hillaker said, but the region has had enough rain that soil moisture levels have increased. Pond and river levels will be the last things to improve in the drought, since they respond after soil has improved.

“In a big picture, it doesn’t make much of a difference,” he said. “This winter season is normally the driest time of the year anyway as far as precipitation. Even a very dry winter isn’t much different than a typical dry winter.”

Hillaker said he has heard many say this summer’s drought was especially bad since last winter was so dry.

“But generally, winter precipitation won’t make much of a difference one way or another,” he said.

Since dry soil cools much more quickly than wet soil, that could cause problems for cities if this winter is extremely cold, he said.

“The ground could freeze to a greater depth, which presents the concern of water lines freezing,” he said.

Agriculturally, farmers might like to see a really cold winter to freeze the ground to ward off adverse types of insects. On the other hand, he said, there are also good insects farmers don’t want killed off.

“So the net change won’t be that big of a deal,” he said.