By Dr. Adam Fenech and Dr. Xander Wang
It is that time of year again for our predictions about how good or bad the winter weather will be this year. As a recap, no one source has had a monopoly on predicting the winter weather well over the past several years. Everyone seems to have an opinion, some of them even educated opinions. Last week brought our first snowfall so I think it is time for the UPEI Climate Lab’s annual winter predictions for Prince Edward Island.
Environment Canada uses climate models to forecast seasonal weather. Climate models are mathematical equations strung together that describe the chemistry and physics of the Earth’s climate system. These equations are calculated using the largest computers in the country, known as supercomputers. Environment Canada forecast temperatures for the coming winter (December, January, February) for PEI to be “above normal,” with precipitation (snow and rain) “normal” for the Island. I must mention, however, that Environment Canada’s seasonal forecast models are accurate for Prince Edward Island only 40-50% of the time (which is not significantly better than chance, meaning flip a coin and you’ll have the same odds of getting the forecast correct). Environment Canada’s seasonal forecasts are accurate in Northern Quebec, the southern Yukon and Baffin Island, but here on PEI, they do not forecast as well.
We all know people who swear by almanacs when forecasting the seasonal weather, so we took a look at the predictions from three of them. The 2021 Almanac for Farmers and City Folk predict temperatures above normal for December and January, and below normal precipitation for January and February; the 2021 Harrowsmith’s Almanac says the winter will “be milder than normal (in the first half) and “start out dry but then will become stormier;” and the 2021 Old Farmer’s Almanac has forecast the PEI winter climate this year to be above average temperatures and precipitation. The Old Farmer’s Almanac is the one we are most familiar with as it has been forecasting seasonal weather since its first issue in 1792 (the time of George Washington’s presidency) using a “secret formula” kept tucked away in a black tin box at the Almanac offices in Dublin, New Hampshire. This “secret formula” has recently been described by Peter Geiger, editor of the Farmers’ Almanac, as “a mathematical formula that gets applied to sunspot activity, planet positions, the effect the moon has on the Earth, and those are the components along with the math to do the weather.”
My own research at the University of Prince Edward Island that examined over 140 years of weather observations in Charlottetown has shown that the climate has definitely gotten warmer and drier, especially over the past 10-15 years or so. And that’s where I put my forecast each winter – to continue the trend and be “warmer and drier”.
Over the past eight years, no one source has been “bang on” in predicting the winter climate – the best has been following the long-term climate trends of warmer and drier but this only worked four out of the past eight years, and really missed our savage winter of 2015. Normally, a PEI winter (the months of December, January and February) averages -6 degrees Celsius and receives about 303 millimetres of precipitation, that’s rain or snow. The 2019-20 Winter was warmer than normal (-4.6 degrees Celsius, or 1.4 degrees warmer) and drier than normal (250 millimetres, or about 17 percent drier than normal). This matched my prediction, but no one else predicted “warmer and drier.”
This inability to forecast seasons accurately is because the year-to-year climate is variable – it goes up and down. Climate is nature’s merry-go-round so it is often difficult to predict the coming season even with supercomputers, secret formulas or historical trends. To emphasize this point, my new colleague at the UPEI Climate Lab, Ross Dwyer, flipped coins to see what Lady Fortune’s forecast for the winter will be – the result being “warmer and wetter”. So there are many forecasts made but only one will be correct. Predictions overall are unanimous for a warmer winter (6 votes) with undecided precipitation (3 for wetter, 2 for drier, and one average rain or snow) for 2020-21.
|Source||Temperature Warmer (+) Colder(-) Average (=)||Precipitation Wetter (+) Drier (-) Average (=)|
|Almanac for Farmers and City Folk||+||–|
|Old Farmer’s Almanac||+||+|
|Chance (Flip a Coin)||+||+|
Questions? Contact Adam Fenech at firstname.lastname@example.org or (902) 620-5220