Sunscreen instead of ski pants? What El Niño could mean for the upcoming Prairie winter
CBC
El Niño is making its return after a nearly eight-year hiatus, and forecasters say it could impact winter weather on the Prairies.
The climate pattern happens when the temperature of Pacific Ocean waters along the equator off the coast of Peru rises above normal.
The air above that water then warms and moves northward.
In Western Canada, this intrusion of warmer air can change the overall pattern of the polar jet stream — a narrow band of fast-moving air that separates colder weather to the north from milder weather to the south.
"El Niño conditions, in general, will give [the Prairies] warmer than average winters and drier than average winters," said Terri Lang, a meteorologist with Environment and Climate Change Canada.
"Those moisture-bearing low pressure systems that travel along the jet will also be ... further north."
But snowstorms and frigid temperatures are still possible, even in an El Niño winter, said Lang.
El Niño is the opposite of La Niña, where Pacific Ocean waters in the same region are cooler than normal. This typically brings more moisture and colder than average temperatures to the Prairies.
The National Oceanic and Atmospheric Administration (NOAA) in the U.S. says the last three years have seen La Niña winters.
The last El Niño, during the 2015-16 winter, was dubbed one of the stronger systems since data collection began around 1900.
That winter, Pacific Ocean temperatures rose more than 2 C above average in the region of the Pacific called Niño 3.4 — the area most watched to determine El Niño's strength.
That event left the Prairies up to 4 C warmer than normal from December through February. It also left an extreme moisture deficit.
Some climate agencies are predicting another strong El Niño this time around, with NOAA forecasting a 55 per cent chance of such an event.
David DeWitt, director of NOAA's Climate Prediction Center, said Niño 3.4 temperatures are around 1.9 C above average and are expected to intensify through December.