Complexities Of Forecasting The Upcoming Winter

If making an accurate 10-day forecast has become more difficult, think of the complexities of forecasting how the entire winter season might play out, months in advance. But this type of long-range forecasting — which doesn’t try to predict the dates of specific storms, but looks more at general weather patterns — is essential when it comes to planning and budgeting for winter snow and ice management operations.

“We ordinarily start thinking about snow in the last week of July,” says Ken Elliott, meteorologist and IT coordinator with WeatherWorks, a Hackettstown, New Jersey-based meteorological firm that provides services to clients in the snow and ice management industry. It usually takes that long to reach the point when until El Niño-Southern Oscillation (ENSO) weather patterns are established enough to have a sense of how the winter might play out in different parts of the country.

This type of long-range forecast is based on which pattern is developing (either warming with El Niño, cooling with La Niña, or neutral), where the forecasters think things will go and historical data for the winter weather that has resulted when these patterns were present in prior years.

Elliott says that a preliminary weather-pattern analysis, performed by James Sullivan and Cody Hewitt at WeatherWorks in early July, indicates a neutral phase of ENSO this winter — neither El Niño or La Niña.

“It more than likely will be what we call a ‘warm neutral’ season,” he explains. “Since El Niño is represented by warm waters in the equatorial Pacific Ocean, it’s likely that the waters will be a bit warmer than average, but not enough so to be classified as an El Niño.”

From a long-range forecasting perspective, a neutral pattern like this is the most difficult scenario, Elliott says; things are a little easier to predict when there’s a pronounced El Niño or La Niña pattern. “Unfortunately, this overall neutrality means other forecast factors, which are harder to forecast at long lead times, will probably have greater-than-normal influences this winter,” he says.

Still, the WeatherWorks team analyzed data from six prior years that had this same scenario and was able to identify some patterns in how the winters played out in those years. “Some are obviously better fits than others, but it’s a starting point,” Elliott says. Some of the trends from those past winters are:

• The eastern U.S. was seasonable to mild early on, with a much colder pattern for February and March.
• The central U.S. experienced conditions similar to the eastern U.S., but the transition to colder/snowier weather seems to have occurred a bit sooner.
• The western U.S. was more changeable, with occasional cold periods, especially during December, January and March.
• Despite some variability (one or two of these six years saw lean snowfall), the overall pattern was for average to above-normal snowfall distribution for a good portion of the country.

And just as a fun, shot-in-the-dark prediction, WeatherWorks says there is a small — but not insignificant — chance that the Southern Plains region could be in for a snowy winter.

With such generalized patterns, it’s impossible to say exactly how much snow any given area will receive this winter. “A single winter storm can throw off the entire winter’s forecast,” Elliott warns. That having been said, Brian Clavier and the team at WeatherWorks assembled data from 15 cities across the U.S. and determined their average snowfalls in the six seasons that seem comparable to our current weather patterns.

“We took that a bit further and created a weighted average, giving a bit more credence to the winters we felt had the best chance to look like 2017/18,” Elliott explains.

In general, Elliott says average snowfalls in the U.S. have been ticking up, and that is a trend that he expects to continue. In many cases, that is due to larger storm events and other anomalies (such as storms in places that don’t often get snow, for example). It’s just another challenge for weather forecasters to contend with.

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