January temperatures went from bitter cold to mild

COLUMBIA, Mo. – Temperatures in January 2015 had a split personality.

“The first half of the month was unusually cold, with some areas 10 degrees below normal,” said Pat Guinan, climatologist for the University of Missouri Extension Commercial Agriculture Program. “Then we had a pattern change right in the middle of the month and parts of Missouri averaged 10 degrees above normal.”

You can blame the jet stream. That river of air about 30,000 feet above us dictates what weather we’ll see at the surface, Guinan said.

“During the first half of January we had a northwesterly flow pattern with bitter cold air coming out of Canada and the Arctic,” Guinan said.

Then the jet stream shifted. By mid-month it was a west-to-east flow, so the air masses were coming off the Pacific Ocean, which is a milder weather regime, bringing milder temperatures to Missouri, he said.

Even with those low temperatures in early January, the average temperature for the month was surprising.

“When you combine them both together, it doesn’t reflect what actually happened in our state,” Guinan said. “It will go down as a marginally mild month with an average of a degree above normal, and it was anything but that.”

As for precipitation, January stayed true to form. It’s typically our driest month, Guinan said. Average precipitation statewide was about 1.2 inches, which is about an inch below normal. There were regional differences. Some parts of far southeastern Missouri saw 3-4 inches of precipitation, while parts of northwestern Missouri had less than a tenth of an inch.

January wasn’t a snowy month. The southern half of the Show-Me State has seen less than 5 inches of snow this entire winter. That’s good news for communities with snow budgets for removing snow and treating roads, Guinan said.

Even with very little snow in parts of the state and some milder days on the horizon, you can’t dismiss Old Man Winter just yet. Things can change quickly in Missouri when it comes to snow events, Guinan said.

“We’ve had snow in April and May in Missouri, so there are still several weeks of potential winterlike events ahead,” Guinan said.

Still, this winter is stacking up to be a mild one.

“Barring any major cold events in February, it will go down as an above-normal winter for our state, which continues a long-term trend,” he said. “Since the late 1980s there’s only been nine winters that were below normal.”

With Missouri’s highly changeable weather, the forecast for February is, as expected, a coin toss.

“According to the Climate Prediction Center, the outlook for February has equal chances to see above, below and normal temperatures and precipitation,” Guinan said.

For more information, visit the Missouri Climate Center website at http://climate.missouri.edu.