Ag Weather Forum

The weather pattern during January has been interesting to say the least. The polar vortex was dominating across much of central and eastern Canada early in the month before taking a 10-day vacation across the northern Canadian islands mid-month. A rebuild of the western North America ridge has allowed a return of the polar vortex to the Hudson Bay region during the past few days bringing back bitter cold to central and eastern Canada.

Temperatures across the Canadian Prairies have shown considerable differences from east to west with cold weather more dominant for Manitoba so far during January while Alberta has seen mild temperatures more of the time. This can be seen in the temperature departures for January through the 22nd.

Manitoba has seen temperatures average 2 to 4 Celsius (4 to 7 Fahrenheit) below normal so far during January while readings are running as much as 3 to 5 C (5 to 9 F) above normal across Alberta. As you might have guessed, Saskatchewan has been stuck in the middle with readings mostly near normal but with readings varying considerably from day-to-day as the Arctic air and Pacific air play tag across the province.

The reason for the temperature differences is with the position of the main upper air weather features across North America. A ridge continues to be dominant near the west coast of North America while the polar vortex has been at home most of the time so far this winter across east-central Canada. This leaves us with a fast moving jet stream flow moving in a southeastward direction across the Prairies.

Disturbances move along the jet stream flow at a rather rapid pace and cause the jet stream to waver back and forth much like when one takes a garden hose and whips it up and down. These waves propagate along it. Each of these waves represents a clipper low pressure area known as an Alberta clipper.

Ahead of the clipper mild Pacific air can shift east to nearly the Manitoba border, but after its passage the arctic air shifts back west and southwest to eastern Alberta and sometimes even further west. This is why Saskatchewan has seen large and frequent temperature fluctuations during the past few weeks. Manitoba has been mostly on the cold side of the storm track allowing for much colder weather and a little more snowfall. Less snow has been noted across the west where the mild theme has been more dominant.

We see more of the same during the next several days, but there are signs that all of the Prairies could share in some very cold weather early to middle of next week for a time. Precipitation prospects continue to be limited to only some light snow with the passage of any clippers zipping through the region. Early winter snow and a decent snow pack in most areas will be maintained during the next few weeks.

Some of the forecasts for February are hinting that the month could turn cold for all of the Prairies along with a return of snowier conditions. Depending on how much snow falls and how fast and when temperatures increase as spring arrives will determine how much of a threat we have for spring flooding and any potential planting delays.

Doug Webster can be reached at doug.webster@dtn.com

(ES)

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