Nancy's Almanac, Feb. 12, 2014: Why do this weekend's temperature forecasts vary so widely? -
Published Wednesday, February 12, 2014 at 1:00 am / Updated at 6:59 am
Nancy's Almanac, Feb. 12, 2014: Why do this weekend's temperature forecasts vary so widely?

Forecasts for high temperatures in Omaha this weekend varied by as much as 10 degrees, depending on the source Tuesday morning.

Some forecasts projected Omaha highs in the low to mid-50s, while others limited the highs to the mid-40s.

The reason for such a wide difference?

Our weekend weather will be affected by a Canadian Clipper dipping down from the north and warm air moving up from the southwest, said Cathy Zapotocny, a meteorologist with the National Weather Service.

The paths and timing of these two air masses is subject to change, especially since the weekend is so far away (the Canadian Clipper was still “at sea” on Tuesday).

As Zapotocny explains it:

Cold air

The Canadian Clipper, traveling along a northwest-to-southeast path, will usher cold air into the northern United States this weekend. Eastern Nebraska and western Iowa are along the edge of that clipper, so our temperatures will vary significantly.

In the space of 100 miles, there's a 10-degree difference in the highs forecast for Saturday. Lincoln's high was projected at 50 degrees, while Atlantic, Iowa, wasn't expected to rise above 41.

Forecasts that have Omaha in the 40s on Saturday are based on the Clipper dipping far enough south for more of the Midlands to catch a taste of that cold air.

Warm air

Clippers rotate in a counterclockwise motion as they travel across the continent (think of a top spinning across the floor). The front edge of the rotation pulls warmth up from the south, while the back edge brings cold down from the north.

The timing of the arrival of the front edge of the clipper will determine Saturday's temperatures, Zapotocny said.

Ideally, the clipper will pull warm air into our region Saturday afternoon as normal daytime warming occurs. If these two happen together, temperatures will rise higher.

If the warmth arrives earlier — overnight Friday — its effect could weaken by Saturday afternoon and temperatures might not climb into the 50s.

Sunday's high will depend on how quickly the clipper heads east as it leaves this area. If it departs quickly, warm air from the southwest could linger another day.

Other factors also affect temperatures, Zapotocny said.

As an example of the complexity of weather, she pointed to the snow cover in Kansas. A blanket of snow absorbs warmth from the air, so the snow in Kansas will remove some heat from southwesterly winds blowing into Nebraska. If that snow melts quickly, more warmth will reach Nebraska sooner.

Brian Edwards, a meteorologist with AccuWeather Inc., said it's possible that the warm air arriving Friday night into Saturday will bring some rain with it.

He said the weekend will be breezy, given the jockeying between warm and cold air masses.

Sources: National Weather Service, AccuWeather Inc.

Current conditions and forecast

Contact the writer: Nancy Gaarder    |   402-444-1102    |  

Nancy writes about weather, including a blog, Nancy's Almanac. She enjoys explaining the science behind weather and making weather stories relevant in daily life.

50th Street to close for bridge demolition
18-year-old arrested in stolen-car case
U.S. Senate candidate Bart McLeay trails his 3 GOP rivals in fundraising
86-year-old Holdrege man killed in weekend collision
New police gang intervention specialist knows firsthand about getting involved with wrong crowd
Teen who worked as a cook is killed in shooting at Benson's Gallagher Park
Finally. Spring expected to return. No, really: Warmer-than-average weather in forecast
Four, including Omahan, vie for police chief position in Council Bluffs
Woodmen request would take nearly $40M in valuation from tax rolls
In TV ad, Shane Osborn says Ben Sasse 'beholden to Washington'
City Council OKs redevelopment plan for north downtown project
Rather than doing $250K in repairs, owner who lives in lot behind 94-year-old house in Dundee razes it
Kelly: New $24M UNO center embodies spirit of newlywed crash victim
Home alone: When burglar broke in, 12-year-old locked herself in bathroom, called 911
High school slam poets don't just recite verses, 'they leave their hearts beating on the stage'
Ben Sasse raises more money than U.S. Senate foes Shane Osborn and Sid Dinsdale
Sweet deal on suite use has MECA board looking at written rules
Inmate accused of partially tearing off another's testicles charged with assault
Crew working to disassemble International Nutrition plant
Lawyer: Man had right to hand out religious fliers outside Pinnacle Bank Arena
Firefighters put out duplex blaze in N.W. Omaha
Coffee with a Cop set for Thursday in Benson
Douglas County offices accepting credit, debit cards
Parched Omaha soil soaks up record precipitation
Engineering student harnesses girl power, starts engineering-science club at Gomez Elementary
< >
Kelly: New $24M UNO center embodies spirit of newlywed crash victim
Jessica Lutton Bedient was killed by a drunken driver at age 26 in 2010. Thursday, the widowed husband and other family members will gather with others at the University of Nebraska at Omaha to dedicate a permanent memorial to Jessica.
Breaking Brad: What do the moon, Colorado senators have in common?
How about that "blood red" moon Monday? It was as red as the eyes of a Colorado legislator.
Breaking Brad: Hey, Republicans, are you ready to be audited?
A quick list of audit red flags: 3) You fail to sign your return. 2) You fail to report income. 1) You are a registered Republican.
Breaking Brad: Next year, Bo Pelini brings a mountain lion to the spring game
Before the spring game, Bo Pelini carried a cat onto the field. With Bo's personality, it'd have been more appropriate for him to carry a mountain lion.
Breaking Brad: Bo Pelini's cat lets spring game intro go to its head
Coach Bo Pelini took the field before the spring game holding a cat aloft. Typical cat. He was undoubtedly thinking, “Sixty thousand people, all cheering for me!”
Deadline Deal thumbnail
Shoreline Golf Club
$40 for 2 Players, 18 Holes of Golf with Cart ($85 Value)
Buy Now
< >
Omaha World-Herald Contests
Enter for a chance to win great prizes.
OWH Store: Buy photos, books and articles
Buy photos, books and articles
Travel Snaps Photo
Going on Vacation? Take the Omaha World-Herald with you and you could the next Travel Snaps winner.
Click here to donate to Goodfellows
The 2011 Goodfellows fund drive provided holiday meals to nearly 5,000 families and their children, and raised more than $500,000 to help families in crisis year round.
Want to get World-Herald stories sent directly to your home or work computer? Sign up for's News Alerts and you will receive e-mails with the day's top stories.
Can't find what you need? Click here for site map »