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Warm, dry weather expected into December

Computer modelling suggests precipitation closer to average levels in January

What a difference a month can make. If you remember back to October, it was a cold and snowy, yet dry month. Temperatures across southern and central Manitoba averaged from 2.5 to 3.5 C below the long-term average, with precipitation also coming in well below average. Jump ahead 30 days and we have gone from well-below-average temperatures to above, with precipitation still running well below average. In fact, it’s almost time to bring up the “D” word for some regions: drought.

Looking back at November, the tone for the month was set early on, as daytime highs soared into the mid- to upper teens, with even a few low 20s from Nov. 2 through to Nov. 8. Several locations broke record highs during this period. In the table here you’ll see the records that were set on Sunday, Nov. 8 as compiled by Environment Canada.

After that warm start, temperatures settled back to around average to a little either above or below average for the rest of the month. There were no real outbreaks of cold air, with the coldest overnight lows only falling to around -20 C and those only on a couple of nights. Daytime highs were almost equally split between above-zero highs and below-zero highs. When all the temperatures are added up and then averaged out, mean November temperatures fell between 0.5 C and 1.5 C above average. The coldest readings were in the central and western regions, with the warmest readings in the south and eastern sections.

Precipitation across all three of the major reporting centres was well below average last month. November averages ranged from 30 to 35 mm of water-equivalent precipitation. For this November, amounts ranged from five to 10 mm across most areas — significantly below average. Except for June across western regions, all 11 months of 2020 have reported below-average precipitation. The Winnipeg region has been the driest. With only one month left in the year, its total amount of precipitation is currently at about 255 mm, which is just shy of 50 per cent of average. While a wet winter or spring can make up for the shortfall, it is something we need to think about.

Who called it?

OK, now on to the December and winter weather outlooks. First, looking back at last month’s forecasts, none of the forecasts were spot on. Several predicted the above-average temperatures, but those same forecasts called for near- to above-average precipitation. If I had to give the nod to just one forecast, it would be the CanSIPS weather model, with its prediction of average temperatures and near-average precipitation.

Now, on to December and January’s forecasts. The Old Farmer’s Almanac calls for a cool, wet December followed by a very warm and slightly wet January. The Canadian Farmers’ Almanac appears to call for near-average temperatures and precipitation.

Moving on to the computer models, NOAA is calling for below-average temperatures and above-average precipitation. The CFS model is calling for a very warm December with near- to above-average precipitation, followed by an abrupt shift to below-average temperatures with near-average precipitation in January. The CanSIPS model calls for near-average temperatures in December with near- to above-average amounts of precipitation, followed by cooler-than-average temperatures and above-average precipitation in January.

Lastly, my look ahead. Instead of going on my gut feeling, I did some poking around, looking at what happened weather-wise in years similar to this one. The first thing I looked at was what the winter was like the last time there was such an active Atlantic hurricane season, which was back in 2005. The winter of 2005-06 was a warm one, with below-average precipitation. Then I looked at previous winters that had similar La Niña conditions as we are expected to have this year: moderate to strong conditions. I don’t have room to list them all, but here is a summary of those years. All of them reported either average or above-average temperatures, with 60 per cent of the years reporting near- or above-average precipitation. The other 40 per cent reported below-average amounts. After examining these years, I’m not sure why it is always reported that La Niña years are cold and snowy. Based on these years, it looks like we have a good chance of seeing a warmer-than-average winter (December is definitely looking to be warm) with near- to above-average precipitation.

About the author

Co-operator contributor

Daniel Bezte

Daniel Bezte is a teacher by profession with a BA (Hon.) in geography, specializing in climatology, from the U of W. He operates a computerized weather station near Birds Hill Park.

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