So far this winter we have seen El Nino's effects more dominant than the more normal arctic cold. During the next week to 10 days, some of both may come to the Prairies and set up temperature extremes from east to west and allowing some to see large gyrations in temperature.
A quick recap of January's climate across Western Canada from tabulations of key weather stations shows that El Nino type weather prevailed even though a couple of short periods of cold conditions did occur. Provincial temperature departures west to east from Alberta to Saskatchewan and Manitoba respectively were plus 1.2, plus 3.2, and plus 2.0 degrees Celsius above normal.
Precipitation totals in the same order from west to east were 89%, 74%, and 63% of normal, while observed snowfall was 83%, 65%, and 58% of normal. Mild, dry conditions are what we expect during a strong El Nino event and that's what the weather dished out.
Snow cover remains lack-luster across most of the Prairies as we pass the mid-winter mark with some parts of southeast Alberta and southern Saskatchewan seeing scarce amounts of snow. Snow depths are less than average for nearly all areas. The accompanying snow depth chart from Environment Canada illustrates today's snow depth measurements.
El Nino is beginning to weaken across the equatorial Pacific but normally it takes several weeks before the weakening shows up in the atmosphere so we are looking for El Nino type weather to last for the remainder of the winter on average. During the next week or so we are likely to see some change for parts of the region as the upper level jet stream flow pattern amplifies.
A strong upper level trough is likely to develop across central and east-central Canada by the time we get to early and mid-next week, while a strong ridge builds along North America's West Coast. You might think a period of severe cold is about to encompass Canada, but it appears that cold weather will take hold for central and eastern Canada for a time and will not be as severe as we have seen in recent years.
The western ridge is far enough east to allow Pacific air to spread into the western Prairies, sending temperatures upward at the same time Manitoba sees readings tumble. During early and middle of next week, temperatures may be below normal across Manitoba and well-above-normal across Alberta. This leaves Saskatchewan in a zone where temperatures may gyrate back and forth for a few days as cold and mild air play tag.
Near the boundary of cold and warm air there is likely to be some light snow at times as milder air overruns the cold air to the east. No heavy snows are expected, but some moderate totals are possible for the eastern Prairies as a couple clipper-type low pressure areas move along the thermal boundary. Low pressure moving along such a strong thermal boundary can be likened to whipping a hose up and down and letting the waves propagate along it.
Eventually it appears that the milder western pattern will begin to take over for all areas as we move into mid-month and the highly amplified upper pattern returns to a flow moving in a west-to-east fashion again. Precipitation amounts may continue to be light with these patterns and how much available moisture is present for spring seeding is something we will have to watch during the next few months.
Doug Webster can be reached at firstname.lastname@example.org
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