Prairie Weather (Rural Roots Canada) –  As December begins, prairie weather warms up, but not for long.

Frost and fog have characterized recent mornings across much of the prairies over the past few days.  The frost decorates the trees, and ices up the ground last Saturday morning near Ryley, Alberta:

Photo: Linda Hunt

 

High pressure has kept the sky mainly clear for the past few mornings, allowing the frost and fog to form.    This is expected to change, as a turn to milder weather begins Monday, along with the return of snow and freezing rain.

As of November 30th, most of southern Manitoba had yet to receive a measurable snowfall accumulation.   There is snow on the ground, though, in most of Alberta and much of Saskatchewan,  thanks to some snowy weather through November.  The map below shows departures from average precipitation.   The brownish colours show where November was drier than average.   The  bluish colours show areas that received higher than average precipitation:

 

Courtesy: Agriculture and Agri-Food Canada 

 

Here are some November snowfall accumulation totals for the month of November, from the CoCoRaHS network of volunteer weather observers:

November Snowfall Accumulations in Alberta

Monday

Alberta

The day begins with a mainly clear sky, which leads to the possibility again of early morning fog and frost.   An upper ridge of high pressure will dominate, but at the surface, a low in the southern Yukon will move southeast, and by midday, there will be snow in northern Alberta, with a chance of freezing rain in the mountains and foothills from Jasper northwest through the Peace region and into northern BC.    By late afternoon, the low moves into northern Alberta, where the snow becomes more widespread, and the freezing rain continues over higher elevations.   South of Edmonton, it should remain dry, and west of Highway 2, it’s expected to remain mainly sunny.  It will be warm across much of the province, with highs of 0 to 5 degrees from the Peace region south to the US border.   In northern and northeastern Alberta, highs will range from -5 to -15.

Saskatchewan

No significant weather is expected in Saskatchewan Monday.   Most of the province will be under a mainly sunny sky,  with a light to moderate westerly wind.   However,  Saskatchewan won’t be able to share in Alberta’s warmth, except for the southwestern corner, where highs will range from 0 to -5.   East of Moose Jaw, and across the rest of the province, it will remain cold, with highs in the south between -5 and -10, and to the north, -10 to -20.

Manitoba

It’s another seasonably cold forecast for Manitoba on Monday, with highs in the -10 to -15 degree range.  Those in the far north of Manitoba, can expect temperatures closer to -30 (not a typo).   Other than light snow around the northern basin of Lake Winnipeg, it will be an uneventful weather day in Manitoba.   No significant precipitation is expected.

 

Tuesday

Alberta

The upper ridge breaks down, and a northerly flow establishes aloft.   Snow will develop across the Peace Region, and through central  and southern Alberta. High pressure to the northeast is likely to create an upslope flow against the foothills and mountains, enhancing the snowfall in those regions.  Travel may be impacted in central Alberta, due to blowing snow caused by a brisk north wind.  Despite the snow, it will be relatively warm, especially near the foothills with highs between 0 and -5.  Elsewhwere, highs will range from -5 to -10.    Snowfall amounts will be relatively minor.   The map below shows the 24 hour snow accumulation by midnight Wednesday morning.

 

 

Saskatchewan

A surface low pressure system moves from central Alberta into southern Saskatchewan during the early morning, then into Manitoba by midday.   Snow will fall along the travel path of the Low, covering much of central and southern Saskatchewan.   In addition, there will be a brisk north wind, and it could be quite blustery.  There may be difficulties in travelling through the area as the stormy weather rolls through.  That said, it won’t be super cold.  Expect some fairly warm weather south of Saskatoon, with highs near -5.  To the north, it will be much colder, as temperatures remain close to -15.

Manitoba

A cold front rolls through central and southern Manitoba Tuesday, bringing snow to the southern half of the province.    The snow will last through the day, but because the snow will be light, and the front will move through rather quickly, snow accumulations will be under 5 cm.  The sky will clear out in the evening, after the snow and the cold front have passed through.   The northern half of the province will miss out on all this, and should stay mainly sunny.   The clearing sky will lead into a cold night, with overnight lows between -15 and -25.

 

Wednesday

Alberta

A ridge of high pressure in the Pacific keeps a northerly upper flow over Alberta.   Embedded in that flow is another low, which will bring more snow to northern  and central Alberta on Wednesday.  Southern Alberta should stay dry.  Southeast of Calgary there will be a partly cloudy sky.  Again, snow amounts will be light – less than 5 cm, with no significant snow anticipated south of Highway 9.   It will be a warm day, with highs near 0 in southern and central Alberta, and as far northwest as the Peace region.   Outside of these areas, expect highs from -5 to -10.

Saskatchewan

A high pressure system over Saskatchewan will keep the sky clear across the province until the late afternoon.  That’s when a Low drops down from the north, and spreads snow across the northern third of the province.   This is nowhere near any agricultural land.   Even as the snow arrives in the north, the southern half of the province will remain under a clear sky going into the early evening.  Overnight, some of the snow may then slump southward as far as the Trans Canada Highway.   It will be a cold day across Saskatchewan, with highs in the -15 to -20 degree range.

Manitoba

Highs of -15 in the south and -25 in the north,  and most of the province will be under sunshine through most of the day.   No significant weather is expected for Manitoba Wednesday.

 

Thursday

Alberta

Unsettled conditions continue in Alberta, with snow and cold weather in the north, and warm weather to the south.  There is a strong northwest to southeast upper flow.   Where the cold weather to the north and the warm weather to the south meet is called a baroclinic zone.  Systems will travel in that zone from the northwest to the southeast during the day, bringing clouds and snow.  Snow amounts will be minimal, in the 2 to 5 cm range.   There is a risk of freezing rain.   The risk is not zero, but it is very slight, so motorists need to pay attention.   Slush is likely to be a concern on many roads.  The map below shows a huge contrast in Thursday afternoon temperatures comparing the north to the central and southern regions.   Right along the line separating the warm from the cold is where Thursday’s snowfall is expected.

 

Saskatchewan

A low pressure system moving through the province from the north to the southeast will bring more snow to Saskatchewan Thursday.  Snow amounts will be light, as the low moves through rather fast.  Travel disruption will be minimal.   The map below shows the amount of snow expected to fall by sunrise Friday morning:

Mild air from the west will boost temperatures above the melting point south of the Trans Canada Highway.   Central Saskatchewan can expect highs between 0 and -10, while in the snowy north, afternoon highs will peak near -15.

Manitoba

As shown on the map above, central and southeastern Manitoba can also expect sow from Thursday into early Friday morning,  due to the passage of a moist, but weak Low pressure system.   After the snow falls in the morning and midday, expect some clearing in the afternoon.  This could help bring temperatures up to the -5 to -10 degree range in the afternoon in southern Manitoba and the Interlake.   In north central Manitoba, highs will be in the -15 to -20 degree range, and in the far north, it will be quite cold, with highs in the mid -20s.

 

Friday

Alberta, Saskatchewan, and Manitoba

In meteorology, there’s something called a reverse temperature trend, and we’ll see that happening across the prairie provinces on Friday.   Instead of rising through the day, temperatures will go the other way, meaning it will cool down as the day goes on.   This animated map shows arctic air plunging southward across the prairies during the day Friday:1

 

 

The advancing colder air signals a change in the weather pattern.   A change that will bring light snow to parts of central Alberta and Saskatchewan, and a few flurries to southern Manitoba.  Thee will be heavier snow over Lake Winnipeg, and in a province wide northwest to southeast band that cuts through Thompson.    Even in the areas of heavier snow, accumulations will be minimal, mostly less than 5 cm.

Saturday

Alberta

With the arctic front to the south, Alberta will have a cold day Friday.  A ridge of high pressure will sit over Saskatchewan, and the return southeast flow around the high will produce snow in much of Alberta.   Expect 5 to 10 cm of snow in northwestern Alberta, 4-7 cm in central and southeastern regions.   In the foothills west of highway 2 and south of the Yellowhead highway, there may be no snow at all.   This is a tough call, though, as the cold weather and snow could extend as far west, through the foothills, to the foot of the Rockies    It depends on whether a downslope wind develops, drying out the foothills terrain.   There is a lot of uncertainty.  In the foothills, highs could warm to between -4 and -8 if the downslope wind develops.   If not, temperatures will be similar to those across the rest of Alberta, where it will be COLD, with highs in most areas near -15.

Saskatchewan and Manitoba

High pressure brings sunshine and clear sky but the lowest temperatures of the season so far are expected in Saskatchewan and Manitoba.  Highs are expected to sit in the –15 to –18 C range, with overnight lows trending toward the mid –20s.   Wind chill values could range from -25 to -35.   That gives a high risk of frostbite after 30 minutes of skin exposure.    Here’s Environment Canada’s wind chill chart:

 

Sunday

​Alberta, Saskatchewan, and Manitoba

The high pressure system that brought the clear and cold weather to Saskatchewan and Manitoba moves to the southeast, allowing for some warmer air to come in from the west.  Under a partly to mostly cloudy sky,  temperatures in Manitoba will remain cold, with highs near or below -20.  Saskatchewan will warm up a bit with highs between -10 and -20.  The biggest changes come in Alberta, where there will again be sharp differences in the weather between the north and the south.   Chinook conditions will develop in the south, and highs will range from -5 to +5.  In central regions, highs will be in the mid minus teens.   Head further north, and it will be much colder, with snow.   Expect snow to fall north of Edmonton,  and temperatures will reach a range of -15 to -25.    The farther north, the colder it will be.

 

Heads Up:

This is from an Environment Canada briefing document:

–Violent wind gusts are possible in extreme southwestern AB on Monday and Tuesday

While Monday and Tuesday are beyond the range of this outlook, the word “violent” grabs attention.    We’ll have an update early Monday morning with our regular weekly outlook at Rural Roots Canada.