Story County is under a Dense Fog Advisory from Feb. 3 until midnight Feb. 4. The fog was caused by a 100 degree shift in the temperature.

From a dry, record-setting cold, to a humid 50 degrees in February, Iowa is experiencing more of its sporadic weather events.

In typical Iowa fashion, a -50 degree wind chill Wednesday turned into a 50 degree Sunday, making Iowa temperatures effectively undergo a 100 degree change over a four-day period. Even without wind chill this difference is 80 degrees — a change National Weather Service meteorologist Alex Krull called “abnormal.”

“While it isn’t wildly unusual, the difference is still out of the ordinary,” Krull said.

These temperatures were reliant largely on the location of the jet stream: The cold air of the Arctic moved with the faster winds that crept south for days, but now the jet stream is moving further north than usual, causing the warmer air to move across Iowa.

Overall, Sunday’s temperatures are about 20 degrees higher than average for this time in February, and other weather conditions are occurring because of these sudden changes.

Dense fog, created by the ice and snow that started to melt Saturday and coupled with a humid front of warm air, occurred Saturday night into Sunday morning.

“We have a lot of moisture that has come into the air right now,” Krull said. “Fog, and even dense fog is occurring across the state with those conditions.”

These weather anomalies will be gone as quickly as they came, however. Current projections show temperatures creeping back to their usual levels — 20 to 30 degrees — as the week progresses, and the humidity will adjust with expected snow falls Tuesday through Thursday.

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