Iowa enjoys, mostly, warmest December
By JOE SUTTER
According to Harry Hillaker, state climatologist at the Iowa Department of Agriculture and Land Stewardship, December 2015 has been one of the warmest on record.
“This would be the warmest December since 1889,” if things continued as they have been, Hillaker said Monday. “But we might not finish that way.
“So far this month statewide average temperatures are running 11.6 degrees warmer than normal, which is pretty substantial,” Hillaker said. “Although that number will be declining as we finish out the month with colder weather.”
There’s also been far more rain and snow this year.
“More unusual than that has been how wet this month has been.
“We’ve easily set a record for the wettest December,” Hillaker said. “Not just wettest December, but wettest of any midwinter month – December, January or February. And certainly with the forecast in the next 24 hours or so adding to that already record total.”
Those records go back 143 years, he said.
In addition, the northwest two-thirds of the state, including Fort Dodge, have seen a lot of snow and rain.
By the end of Monday, according to the Iowa mesonet website, north central and northwest Iowa had snow accumulations between 6 to 10 inches throughout that day.
Four out of the last five Decembers have been exceptionally warm, according to Hillaker. December 2013 was unusually cold.
This year’s El Nino conditions certainly have an impact, although there are a number of other factors, said Allan Curtis, a meteorologist with the National Weather Service.
“It tends to bottle up the cold weather north in Canada. As a result we don’t get as many of those Arctic blasts,” Curtis said.
El Nino is caused when the typical prevailing winds across the Pacific Ocean change, Hillaker said. Usually the trade winds blow from the east, but during an El Nino event the trade winds get much weaker, and sometimes even reverse slightly.
This year’s weather is pretty typical for El Nino, Hillaker said. But the latest weather outlooks say warmer and wetter weather may not last.
“It looks like January will be starting off with more typical weather,” he said. “It would be somewhat surprising if we had those two months as mild as this one has been.”
And though a lot of that extra wetness has fallen as rain, there’s been plenty of heavy snow this year, in spite of the warm weather.
“Just because we’re having a warmer winter than last year, that doesn’t necessarily equate to less snow,” Curtis said. “It all depends on where that sweet spot is when a system comes through. If we’re right around freezing, cold enough to get snowfall, we could get a couple heavy snowfalls.”