Record-setting warmth in February is punctuating what has been the mildest winter on record so far.
“This warmth comes at the tail end of a winter that overall has really been mild,” said Barbara Mayes, a meteorologist at the National Weather Service.
That changes soon as the region gets a reminder of winter later this week: A mix of rain and snow is forecast Thursday into Friday, with overnight temperatures dropping into the 20s.
But, overall, Omaha is in the midst of a number of weather records, according to Mayes and climatologist Ken Dewey of the University of Nebraska-Lincoln:
» Warmest stretch of days in mid-February (Feb. 10 through 19 and counting), with an average temperature of 44.9 degrees, nearly two degrees above the previous record set in 1976.
» Most consecutive days in February with a high above 50 degrees. The previous record was nine, and so far the month has had 10 in a row, with more to come.
» Likely record-number of February days above 70 degrees. Omaha’s record is three. The city has had two already, with two more days, today and Wednesday, forecast to top 70 degrees.
» And yet another month — the 18th in a row — with the average temperature above normal. Omaha hasn’t seen a month average below-normal temperatures since August 2015, according to the weather service.
Temperature records are based on 146 years of weather service statistics.
“It has been a very strange winter in the Midlands,” Dewey said. “Tornadoes in December, rain instead of snow, freezing rain instead of blizzards, and a February with record warmth.”
In a sense, it’s been so warm that Nebraskans have had a taste of winters farther south, he said, quipping that people have had a chance to be “snow birds,” without traveling.
Despite February averaging nearly 10 degrees above normal, the month itself won’t set a record for temperature, Mayes said. That’s because it’s been so dry — up until Monday’s rain — that temperatures have dropped off sharply at night, once the sun sets (much like in a desert). This has pushed down temperatures overall.
So far, Omaha’s average temperatures would put this month in ninth place among warmest Februarys because the low temperatures are closer to normal.
Take out those nighttime lows and the picture changes significantly, according to numbers crunched by Dewey, an applied science professor at UNL. The month ranks third-warmest, based on daytime highs only, he said.
So far, Omaha’s winter is the mildest since the advent of modern record-keeping in 1950. Well-above-normal temperatures and below-normal snowfall underlie that winter ranking.
What’s behind the warmth?
Plenty of sunshine and a jet stream remaining well north of the region have helped create the record highs, forecasters have said. The jet stream is a barrier to arctic air, and as long as it stays north, that cold air remains bottled up. Later this week, it’s forecast to dip south and pull in some cold air behind it.
Dewey said other factors also are at play in generating the warmth.
A lack of snow cover and the fact that the top few inches of soil have thawed is keeping temperatures up, Dewey said. Solar energy that would normally bounce off of snow or get consumed melting the snow and frozen ground instead has gone toward heating the air.
A cool-down arrives Thursday along with a moisture-rich storm. Highs on Thursday are forecast in the low 50s. Friday through Sunday, highs are likely to be in the 30s and lows in the 20s.
Rain is forecast Thursday, and as temperatures drop overnight the moisture will shift to snow and then fluctuate on Friday between snow and rain. Friday is likely to be an unpleasant day, given the forecast for a rain-snow mix and strong winds.
The arrival of this storm system heralds a long-term change in the weather, Dewey said. The outlook for the end of February and start of March favors colder and wetter-than-average weather in the Midlands.
World-Herald staff writer Andrew J. Nelson contributed to this report.