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UPEI CLIMATE LAB: Weather predictions for P.E.I.’s 2020-21 winter

Ross Dwyer of the UPEI Climate Research Lab flips the school's prediction coins, which show a warmer and wetter winter 2021.
Ross Dwyer of the UPEI Climate Research Lab flips the school's prediction coins, which show a warmer and wetter winter 2021.

Dr. Adam Fenech
and Dr. Xander Wang

We have already had 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 P.E.I. to be “above normal,” with precipitation (snow and rain) “normal” for the Island.

We all know people who swear by almanacs when forecasting the seasonal weather, so we took a look at the predictions from four 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 P.E.I. winter climate this year to be above average temperatures and precipitation.

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 P.E.I. 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 (six votes) with undecided precipitation (three for wetter, two for drier, and one average rain or snow) for 2020-21.

Dr. Adam Fenech is associate dean of UPEI's School of Climate Change and Adaptation. Dr. Xander Wang is assistant professor of climate change and adaptation.

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1 being least likely, and 10 being most likely

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