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How to assess which long-term winter weather predictions are reliable

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Throughout history, people have looked for signs of the coming winter and turned to the sky, land and water. Will it be mild or cold? Snow, rain or drought? Humans are observing the behavior of animals and plants, clouds, oceans and, in recent decades, computer models to provide clues to the coming winter. After all, knowledge is power, and any advance warning of severe or mild winter conditions can prompt people to prepare in advance.

But who can you trust when it comes to winter vistas, and which ones are best left to the entertainment department? When making decisions based on information about the winter outlook, consider relying on expert best practices—not a farmer’s almanac or caterpillar.

How hard will the winter be? Six organizations make forecasts.

The National Weather Service’s Climate Forecasting Center

Each month, the National Weather Service Climate Prediction Center broadcasts an outlook for the 12 upcoming three-month “seasons” with maps showing areas with unusually warm or cold temperatures and unusually wet or dry precipitation.

Prospects are quoted as odds, which tilt those odds toward a preferred category, just as weighted dice can favor one roll over another. CPC never guarantees or predicts specific temperatures or rainfall levels. The inputs for CPC forecasts are known and based on published methods. The review, in which they compare forecasts to results, is public and lends credibility to their methods and results.

The outlook relies heavily on climate change trends, the influence of El Niño or La Niña, and some longer-term computer models, but very few global patterns have been confidently associated with the coming winter when looking more than a month ahead.

Interpreting the scenic maps can be challenging. If you want to dig deeper, the National Weather Service offers training to help you.

A handful of other research-based units create seasonal or sub-seasonal winter prospects. One of these, the International Research Institute for Climate and Society at Columbia University, is working with the CPC to extend the seasonal outlook, including winter outlook, to a global perspective. Experts from both groups work together to create the forecasts, sharing their cumulative expertise in a decades-long partnership.

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Another entity providing predictive winter information is Verisk Analytics, a private company primarily through the work of a scientist: Judah Cohen. While Cohen’s work is being done for a private company, he is publishing his methodology. Many of his methods are still being tested and debated by fellow climate scientists — something he invites with weekly discussions.

Winter is coming: Here’s what you should know about long-term weather forecasts

Traditional indigenous knowledge

Indigenous peoples around the world have tracked winter weather patterns for generations, passing on their knowledge in writing, pictures, or orally through their own traditions. Until recently, the methods of Western scientists have remained independent of traditional indigenous knowledge. As these scientists connect to indigenous knowledge of the environment and ecology, they incorporate viewpoints that have not been considered in the past.

The links with traditional indigenous knowledge are new, and in some cases tricky, as Western scholars learn to nurture relationships with and trust indigenous peoples.

What does it mean to say that a February winter will be “cold, snowy” for a three-week period, especially in snowy climates? Is a blizzard enough? How cold does it have to be to be considered “cold” in the Almanac? These questions are among the many reasons why it is nearly impossible to validate farmers’ almanacs. The language is too vague, too wide a range, and too long a period of time to give the outlook a hit or miss.

According to the Farmers’ Almanac, the forecasts are based on a formula that accounts for sunspot activity, lunar tides, and planetary positions, but the authors do not publicly publish or discuss their methodology, leaving the scientific community in the dark about its validity. Although the Farmers’ Almanac forecasts are 80 to 85 percent accurate, a closer, independent look at the results shows that the almanacs are, at best, a coin toss.

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Punxsutawney Phil and his predictions are the subject of an unofficial holiday, a film and a large gathering of suits proclaiming whether the end of winter is near. According to legend, the groundhog that sees its shadow is frightened back into its hiding place for another six weeks of winter, while the groundhog that does not see its shadow comes out and the end of winter approaches. Unfortunately for Phil’s fans, he’s worse than a dartboard at predicting the end of winter. Take the word from the National Centers for Environmental Information — the groundhog is not a forecaster.

Woolly bear caterpillars are often credited with the ability to predict the winter season based on the thickness of their brown and black stripes, with thicker black stripes predicting a longer, harsher winter. But their stripes have nothing to do with the weather – their width depends on the length of time they have been eating, the age and the species of the caterpillar. Woolly caterpillars crawling south do not predict a harsh winter, nor does moving north portend a mild winter – their movement is guided by finding shelter under a rock or bark, or perhaps a tidbit.

Legend has it that years when many acorns fall from the oak trees (“mast years”) bring harsh winters and provide additional food for squirrels, chipmunks, and other foragers. Instead, it turns out that mast years are more closely tied to the weather of the past season than to the future. Oak blossom in spring depends on winter and early spring temperatures leading into the flowering season. Mild winters without deep spring frosts are more favorable for flowering, resulting in more acorns developing.

While geese migration patterns can predict near-term weather, they are not a sign of winter to come. Geese can fly high in high pressure weather when the denser air allows them to ascend more easily. On the other hand, they tend to fly low in low-pressure weather, which usually entails more volatile conditions. Geese can migrate just before a cold front, heralding the arrival of a cold-weather spell. But cold weather in autumn does not predict all of the coming winter.

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Table of Contents

Possibly reliable sources

Local television meteorologists and private companies

Some local meteorologists and private weather companies publish winter forecasts, often without fully explaining their methods. If the methodology is not known, it cannot be tested by other scientists to verify its accuracy. When view detail is described in words rather than degrees and inches, its accuracy is difficult to assess. Some local meteorologists and private weather companies use a robust and transparent methodology for their forecasts, but others do not. Use with caution.

Not every relationship between animal behavior and the coming winter has been tested, so to say they are all mythology would be irresponsible. An animal or plant is unlikely to hold the key to the upcoming winter.

Researchers need to do more research to fully understand the relationship between the behavior of some animals and the environment. Such animal behavior be better understood as Western science blends better with traditional indigenous knowledge to accommodate the long history of observation and understanding of indigenous peoples.

Barb Mayes Boustead is a meteorologist and climatologist living in the heart of the Great Plains. Her interests include the intersection of weather and climate, particularly in weather extremes, as well as historical weather events such as the one that is the focus of Laura Ingalls Wilder’s “The long winter.” She is an American Association of State Climatologists Dissertation Award winner and past President of the Laura Ingalls Wilder Legacy and Research Association.

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