Prairie Weather (Rural Roots Canada) – Drought expands…will the Polar Vortex rescue us?
Late last week, there was a sobering update to the Canadian Drought Monitor. Heading into winter, well over 80 percent of the prairies are abnormally dry or in drought. The situation in the rest of the country is similarly dire. You’ll find more details in a story we posted Friday.
It is about to get considerably colder toward the end of the month. European meteorologists have brought attention to the likelihood of a Sudden Stratospheric Warming (SSW) event for the latter half of November. Long story short, high pressure over the Arctic will cause sudden warming in the stratosphere, which will destabilize the upper flow in the Arctic, unleashing the dreaded and often misunderstood Polar Vortex. That will bring cold and snowy weather to the prairies, the rest of Canada, and the northern United States. In the article linked above, it is suggested we’ll have a “December to remember”.
Latest model guidance shows the wintry weather will show up on the prairies in the last week of November.
Let’s go behind the scenes. It’s no secret that weather forecasters use computer models to come up with their outlooks. Some even report “what the models are saying” on their websites and broadcasts. Models are not forecasts. Models are tools to make a forecast. Just like a hammer is a tool to make a coffee table. The end user wants the table, not the hammer. The end weather user wants a forecast, not a model.
That said…..let’s look at some models!
The charts below are generated by the NAEFS, the North American Ensemble Forecast System.
Output from the NAEFS concur with the theory of polar cooling after stratospheric warming, beginning in the last week of November.
Here are some charts:
Calgary
Regina
Winnipeg
I could add many more charts to this page, but they all show the same thing- colder and snowier weather for the last week of November.
The colder weather arrives next week, on or about November 24h. Until then, a broad upper ridge over the Prairies will keep winter away this week, with only a couple of weak systems brushing the region. Expect generally mild conditions for mid-November, occasional fog, and only light or localized snow except in far northern areas.
Monday
Alberta, Saskatchewan, Manitoba
Other than snow sneaking into northern Alberta from a Low in central BC, the prairies will be dry on Monday. South of a line from Peace River to Fort McMurray, it will be mainly sunny in Alberta. North of that line, there will be snow. Manitoba and Saskatchewan will stay dry. In southern Saskatchewan, expect brisk wind from time to time, in the 20-30 km/h range, from the southeast. While the three provinces will experience similar weather, there will be big temperature differences. Southern Alberta will see double digit highs. Central Alberta and Southern Saskatchewan will reach the 5-10 degree range. Northern Alberta and Saskatchewan, along with all of Manitoba will remain below freeing, with highs between 0 and -10.
Tuesday
Alberta
A low pressure system will form in southwestern Saskatchewan, sending moisture back into southeastern Alberta. Early morning rain is likely from Lethbridge to Medicine Hat, and north to Coronation. At the same time, an upslope flow will produce some snow between Calgary and Banff, potentially affecting travel on the Trans Canada Highway. By midday, the rain and snow end, and in the afternoon, sunshine returns to the region.
Later in the day, in the afternoon and evening, snow will develop in central Alberta, including the Red Deer, Sundre, and Edmonton regions, as yet another low forms to the south, hear Longview. That same low will draw warm air into southeastern Alberta, and in the late evening, rain can be expected in southeastern Alberta, including Taber, Bow Island, Medicine Hat, Suffied, and Cypress Hills. South of Red Deer, highs will be in the low single digits. North of Red Deer, it will be cooler, with highs within a few degrees of -5.
Saskatchewan
A Low pressure system just southwest of Saskatoon will spread early morning rain across central Saskatchewan, and snow to the northeastern part of the province. About 5 mm of precipitation is expected. The low will weaken, and the rain tapers off, leaving behind a mainly cloudy sky for the remainder of the afternoon and evening. South of the Yellowhead highway, highs will be a few degrees above zero. North of the Yellowhead, highs will be a few degrees below zero.
Manitoba
While southern Manitoba stays dry and partly cloudy, a weak cold front will drag snow across the northern part of the province, and the northern Interlake, but well away from agricultural land. The result being that southern Manitoba will remain uncharacteristically snow-free going into the second half of November. In the south, expect some fog patches in the early morning. Southwestern Manitoba’s highs will be a few degrees above zero. In northern Manitoba, the Interlake, and the Red River Valley, highs will be a few degrees below zero.
Wednesday
The map shows the precipitation that will cross the southern prairies on Wednesday. Blue is snow, green is rain, pink is a mix.
Alberta
As the map above shows, a weak Low will form in the southwestern Alberta foothills earlier in the day, and quickly move east. Snow will begin in the early morning in central Alberta, cross the province quickly, with the sky clearing in the afternoon. Expect 5-10 cm in the Edmonton/Vegreville area, and similar amounts in east central Alberta, from Medicine Hat north to Lloydminster. By afternoon, the moisture will have moved into Saskatchewan, and high pressure will clear the sky. South of the Trans Canada highway, expect highs from 0 to 5. North of Highway one, temperatures will stay below the freezing point, with highs ranging from 0 to -6/
Saskatchewan
Referring to the map above, you’ll see a band of snow will move from west to east across south central Saskatchewan, just north of the Trans Canada Highway. That snow is generated by a weakening low as it crosses the southern part of the province. South of the Trans Canada Highway, some rain is possible, as highs in the area will reach the low single digits above zero. To the north, it will remain below freezing, with highs close to -5. Snowfall amounts will be near 5 cm.
Manitoba
Fog patches are possible again in the early morning Wednesday, followed by brief clearing. Expect rain to develop south of the Trans Canada Highway by midday. This is from a developing Low pressure system that will form near Portage La Prairie during the afternoon. As the low forms, the rain will intensify, and snow will spread into the Interlake.
As the Low moves east, the circulation will shift to the north and northwest, drawing colder air into the area, changing the rain to snow in southern Manitoba during the evening. The precipitation will continue into early Wednesday morning. 7-10 mm of rain or snow, or both, can be expected. Highs in the southern half of the province will rise a few degrees above zero. In the northern half, highs will come in cooler – a few degrees below zero.
Thursday
An outbreak of colder weather begins. As the map below shows, with the exception of southern Alberta, afternoon temperatures across the prairies will remain below the freezing point:
Alberta and Saskatchewan
High pressure over northern Saskatchewan will keep the two provinces dry. That high, combined with a weak low near Claresholm, will produce an easterly wind in southern Alberta. The air will be dry, so this upslope situation won’t result in any precipitation. Southern Alberta will be mainly cloudy, but the remainder of the two provinces will have a sunny day. Temperatures for late afternoon are shown in the map above.
Manitoba
A departing Low pressure system will head into northwestern Ontario, but snow will linger behind. For most of the day, snow will fall across southern and central Manitoba, with afternoon clearing from the west. Most of that clearing won’t begin until about sunset, so it will be a snowy, cloudy, cool day. Afternoon temperatures are shown on the map above. Snow accumulatins, especially in the eastern half of the province are likely to range from 5 to 10 cm, though snowfall accumulation forecasts this far out are not exactly exact.
Friday
Alberta, Saskatchewan, and Mantioba
A ridge of high pressure will keep all three prairie provinces dry on Friday, with no significant precipitation. Some downslope wind in southern Alberta could make it quite breezy there, especially south of highway 3. All three provinces will have a mainly sunny day. In southern Alberta and southwestern Saskatchewan, south of the Trans Canada Highway, temperatures will climb a few degrees above the melting point. Elsewhere, the prairies will continue to be locked into subfreezing weather, though not particularly cold, given the time of year.
Saturday and Sunday
Alberta, Saskatchewan, and Manitoba
Across all three provinces, Saturday’s weather is expected to be similar to Friday’s, with dry weather, and warm conditions south of the Trans Canada Highway in Alberta and Saskatchewan. The rest of the two provinces, and Manitoba, will continue with sub zero temperatures. Things change Sunday, as a low develops early in the day in Alberta. This will be a clipper system, moving rapidly across the southern prairies, but not starting to produce precipitation until it reaches southern Saskatchewan by sunrise.
Because of the temperature profile, it’s nearly impossible to pinpoint what kind of precipitation will fall. It could be rain, snow, or a mix of both, depending on the location and timing. We’ll have an update on that in our post on Thursday. By the afternoon the system is producing snow in southern Manitoba. Across all three provinces, high temperatures will be below zero, except for areas near the US border, where it would warm to a range of 0 to 5 degrees.
This will be a good week for transport. Any movement of grain or equipment should be completed this week, ahead of possibly colder and snowier weather next week.
COMPARE: Prairie Weather This Week – November 10
