Weather service trying new winter forecast method

Now that most of the leaves are on the ground, our attention turns to what’s around the corner: The Big Chill.

This is Nebraska and winter is unavoidable.

So how bad will it be?

Are we talking a winter like last year? When the Omaha area saw 27.4 inches of snowfall, which was above average for the area, but also had nearly 7 inches of precipitation – thanks to a very rainy December – which was the second most precipitation on record.

Or will it be like the winter of 2014, when there were only 13.8 inches of snowfall? For the record, “normal” snowfall for the Omaha area is considered 26.4 inches.

The National Weather Service’s (NWS) answer for this winter is “to be determined.” Thursday, Nov. 10, is Winter Weather Awareness Day so it isn’t too early to start looking ahead.

Last winter’s strong El Nino year will give way to a La Nina weather pattern that pushes the Pacific jet stream higher into the northwest U.S. and drops it lower into the Plains, bringing with it cold air.

In Nebraska, we tend to be between the areas influenced the most by La Nina, especially a weak one. Our winter weather patterns are more likely determined by factors that cannot be predicted months in advance, so we may have to wait a little longer for more clarity.

winter weather

Cathy Zapotocny, meteorologist with the NWS, looks over data on a bank of monitors at the service’s Valley location.

The weather service is making some changes this year in how they will make those determinations. The “Probabilistic Snow Experiment” is something 50 National Weather Service forecast offices, including the local office in Valley, are participating in.

It means the Valley office will provide snow forecasts with a level of confidence and range of possibilities – from the minimum, to most likely to the maximum possible. It’s a pilot program meant to give people a better idea of what they can expect for winter storms in an area that forecasters say is very hard to predict. Here, the signals that indicate what to expect aren’t as strong as other areas of the country, said one veteran meteorologist.

“There is a lot of variance in our area, it can easily switch,” said Cathy Zapotocny, a meteorologist with the NWS. “A few degrees means the difference between rain falling or snow falling. We are trying to convey the uncertainty when predicting these storms.”

The local office in Valley only predicts out seven days. Most storms remain ever-changing and really only come into clearer focus in the 24 hours before they hit. Along with forecaster input, there are more than 70 U.S. and international weather models that will be used.

“We find when we start putting numbers on it, people think about that highest number,” she said. “What this will do is provide a range of possibilities. The main thing we are trying to convey is the uncertainty. When you have storms capable of 12 or 15 inches there are going to be people who don’t see anything and there are going to be people who see 12 inches. For us it is always the question of who gets what.”

Zapotocny used last winter’s Groundhog Day storm as an example. Five days ahead of the storm, models showed northwest Missouri and southwest Iowa could get the maximum amount of snow. But as the storm approached, it tracked north and northwest so when it hit, it was northeast Nebraska that actually got the heaviest snowfall.

“That just shows over the course of five days how the forecast changes,” she said.

Zapotocny said these forecasting changes will hopefully give people a clearer idea of what is possible for snow storms this year. In the meantime, it might not be a bad idea to make sure the snow blower is serviced and your emergency snow kit is ready.

Because we all know what’s coming. Sooner or later.

Jason Kuiper

About Jason Kuiper

Jason Kuiper joined OPPD as a communications specialist in 2015. He formerly worked as a staff writer and reporter at the Omaha World-Herald.

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