This winter has exposed an embarrassing truth about Nebraska and Iowa weather:
It has no sense of self, it's fickle.
Instead, the Midlands take on the personality of whatever domineering force is careening through the neighborhood.
This winter, that “whatever” is the jostling between stubborn masses of Arctic air in southern Canada and warm, dry air in the Southwest.
Because eastern Nebraska and western Iowa are on the dividing line between these systems, the area's weather feeds off one or the other, depending, in a sense, on which way the wind is blowing.
The result is a confusion of springlike and Arctic weather along the Missouri River valley. Farther west in Nebraska, the warmth has been more consistent, and to the east in Iowa, the cold has persisted.
Ken Dewey, a professor and applied climatologist at the University of Nebraska-Lincoln, said this winter may seem unusual, but it isn't.
“We've had other winters like this ... We just haven't had one like this in a while,” he said.
Dewey and Al Dutcher, Nebraska state climatologist, said it's hard to say when a similar winter occurred because of the variables involved.
Steep and sudden declines in temperatures occur in this region during winter when fast-moving weather systems known as Alberta Clippers dive south out of Canada and tug at the edge of the Canadian cold air mass.
As these clippers move out, they take the cold with them. After the bitter cold air heads off to the southeast, warm air from the Southwest rushes in to take its place.
Sunday's high of 65 degrees in Omaha was more than 20 degrees higher than last Saturday's.
But by Monday night, the temperature had dropped 62 degrees to a low of 3.
Dewey and Dutcher said these clippers come through routinely. Dutcher said the last winter with so many clippers was probably 2000-01. But temperatures that winter didn't swing to the extremes of this winter because that season's snowy ground muted the warm-ups.
Indicators of how unusual this winter is:
» Daily low temperatures in Omaha are the 10th-lowest since 1900, said Bryon Miller of the National Weather Service.
» Lack of snow and rain has made this the third-driest winter so far. The bare ground can intensify the warmth when a warm front moves in.
Experts understand the mechanics of what's happening, but not enough to explain why it's unfolding the way it is.
“If we knew what caused this pattern to develop, that would be great because then we would be able to know when it might end,” Dewey said.
Bob Oravec, a meteorologist with the Weather Prediction Center for the National Weather Service, said this pattern also is responsible for the Midlands' dry winter.
Omaha has had about 5 inches of snow this season, which is about 8.5 inches below normal.
Oravec said the mass of warm, dry air is blocking moist air from the Pacific Ocean, preventing it from entering the continent in the Southwest.
This affects the Midlands because Pacific moisture moving up from the Southwest is crucial for rain and snow. Many Midlands storms arrive on shore in the Southwest, cross the southern Rockies and head northeast across the Plains.
'You're pretty much cut off from any source of moisture,” said Oravec, who issues national forecasts from the weather service's College Park, Md., station. Instead, the heavy snows are falling across the northern tier of the country, in the Great Lakes and East Coast.
Oravec said the odds favor a continuation of this roller coaster pattern in the near future, though a change could be coming in early February.
The change could even include snow. However, it's still too early to offer forecasts with any degree of confidence.
“The one thing about weather patterns is they don't typically last,” Oravec said. “They always change. You just never know how long they're going to last.”