Rebecca LoroffAppleton Post-Crescent
When the highs are above average for early November, it may seem too early to think about mittens, ice scrapers and snowflakes. But with the leaves mostly gone and temperatures in the 20s and 30s coming this weekend to most of the state, it's time to look ahead to what winter might bring.
Every autumn, organizations that predict the weather release their seasonal outlook for the coming winter from November to March. These seasonal outlooks try to predict how cold the weather will be and how much snow different regions of the United States will get. Three of the most famous seasonal outlooks come from AccuWeather, the Old Farmer's Almanac and the National Oceanic and Atmospheric Association.
All three publications have predicted a Wisconsin winter that could be colder than usual, and AccuWeather and NOAA have predicted a wetter-than-normal winter for eastern Wisconsin. However, the methods these organizations use and the way they present their conclusions are different.
How is a seasonal outlook different from a weather forecast?
Weather forecasts predict day-to-day conditions: how much rain will fall, how much will temperatures change and whether we can expect severe events like thunderstorms and tornadoes.
Three-day forecasts are now "actually quite reliable, and you can get some signals still out to maybe seven to 10 days. But after that ... there's not really much predictive usefulness," said Paul Roebber, distinguished professor of atmospheric science at the University of Wisconsin-Milwaukee.
Rapidly changing conditions in the jet stream and atmosphere make it "impossible" to forecast daily weather longer term, he said, adding, "It's not a matter of technology. It's a matter of physics."
Seasonal outlooks, on the other hand, are in the realm of climate science, which attempts to predict longer-term trends spanning up to a year, according to climate.gov. These kinds of outlooks don't try to predict inches of rain or the daily high temperature. Instead, they estimate how much a season will change from its normal standards.
More:Expect a colder Wisconsin winter with more snow in some areas, according to Old Farmer's Almanac
More:Opinion: Here's hoping that the Old Farmer is wrong for a change this winter
How do forecasters make seasonal outlooks?
For seasonal outlooks, scientists and forecasters look to climate trends that affect entire continents, like this year's La Niña or an underwater volcanic eruption in Tonga last January that spewed large amounts of water vapor into the atmosphere.
To make their predictions, the Old Farmer's Almanac forecasters use a "secret weather formula" devised by the almanac's founder in 1792 that remains locked in a black box, according to the almanac's website. While it's unclear what role this formula plays in their weather predictions, the almanac's editors claim their predictions are based on sunspots, climatology and meteorology.
AccuWeather, however, goes into a bit more detail about its methodology in its seasonal outlook. Creating the outlook, according to the website, "involves a team of veteran long-range forecasters analyzing computer models, looking at how previous winters have played out and using their own personal experience."
In practice, according to AccuWeather senior meteorologist Paul Pastelok, that means the AccuWeather team looks at forecast modeling and how years similar to this one have played out, as well as water temperatures across the globe and other conditions that influence weather. Pastelok and his team then create a "consensus" forecast based on all these factors.
NOAA released its winter outlook for this winter in late October. The main factor in this year's prediction, according to noaa.gov, is La Niña, a pattern of colder ocean water at the equator in the Pacific Ocean. This will be the third year in a row that La Niña influences winter weather, though its effects can be unpredictable, said Jon Gottschalck, chief of the Operational Prediction Branch at NOAA’s Climate Prediction Center
Besides La Niña and other global climate cycles, NOAA also uses numerical prediction models and sea-surface monitoring to help develop its winter outlook, Gottschalck said. NOAA uses this data to develop maps that show the likelihood of changes from normal winter weather, such as the odds of colder or wetter weather.
Since the methods these three organizations use are different, it's hard to compare the accuracy of their outlooks. For example, Pastelok says his team forecasts "direct departures" from the normal winter weather expressed as a percentage, while NOAA gives its results as a probability for changes.
However, Pastelok emphasized that his organization and NOAA share knowledge and research, especially as researchers determine how weather norms are changing with the climate.
More:Large parts of Wisconsin could see a snowier than normal winter, according to AccuWeather's long-range forecast
More:'Triple dip' La Niña is on the way. Here's what it means for weather in the US
What does that mean for day-to-day life?
Besides curiosity about how climate prediction works, knowing what the winter might bring helps when you're making long-range decisions affected by weather.
For example, Roebber said, if a winter might be colder, utility companies can prepare by stocking up on buying energy at a lower price. Even if a seasonal outlook doesn't turn out to be completely correct, he said, it allows people making those kinds of decisions to assess and manage risks.
Or, to put it another way: a seasonal outlook might help you decide whether or not you need a new snowblower, but a weather forecast — no further out than three to seven days at most — tells you when you can expect to use it.
More:Winter weather is coming: It will be warm, dry in South and East because of La Niña, NOAA says
Rebecca Loroff is a breaking and trending news reporter for USA TODAY NETWORK-Wisconsin. Contact her at 920-907-7801 or rloroff@gannett.com. Follow her on Twitter: @RebeccaLoroff.
