Prairie Weather (Rural Roots Canada) – Now that it’s officially fall, summer weather returns to the Canadian prairies!  Very warm weather, bordering on hot, with minimal rainfall, can be expected this week across Alberta, Saskatchewan and Manitoba.
Fall arrived early in the morning of Sunday, September 22, at 6:43 mountain time, 7:43 central.

Make hay while the sun shines.

A ridge of high pressure over the prairies will dominate the weather pattern all week.   Daytime highs will be in the mid to high 20s for most of the week, and the sky across the agricultural prairies will remain mostly clear.    At this time of year, a clear sky at night allows temperatures to drop fast and far, allowing for the risk of frost.  Not this time.   Overnight frost is unlikely anywhere this week, except perhaps for the mountaintops.

A big Gulf of Alaska storm is forcing the higher pressure this week over the prairies, so while Alberta, Manitoba, and Saskatchewan experience summer-like conditions, the west coast will endure heavy rain, snow, and runoff.

The only significant rain event this week on the prairies happens early Monday morning.  Well before sunrise, a Low pressure system just northwest of Lloydminster will spread a band of rain across Alberta and Saskatchewan, and it will continue during the day on Monday.  The fast moving Low will weaken as it moves east, and the rain won’t make it as far as Manitoba when the Low arrives there at the end of the day.  The heaviest rain from this system will fall in a line from Grande Prairie, through Edmonton, to Regina.   Because the system will move through very fast, rainfall accumulations will be minor, and will have little effect on soil moisture.

The dry weather this week will be welcome news for the many farmers who had to suspend harvesting operations last week due to rainfall and heavy morning dew.

This first map shows total rainfall expected up until the evening of Sunday Sept. 29. Much of southern Manitoba and part of southwestern Alberta can expect no rain at all, and most of what you see in Saskatchewan and Alberta will fall Monday. Afterward, it’ll be dry.

While much of the harvest is in, farmers are working on spring cereals, pulses, and canola, and crop reports from each of the three provinces show that work remains ahead of the normal pace, despite last week’s weather delays.

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Here’s how the warm, dry week will play out:

Monday:

As mentioned, this is the wettest day of the week, as a  Low pressure system crosses the prairies, and drops some rain on Alberta and Saskatchewan.   This will likely be the only rain event of the week.  And, as the map above shows, the most widespread accumulations will be 10 mm or less, with central Alberta and parts of southwestern Saskatchewan receiving about 20 mm.  The wet weather happens in Alberta in the early morning, and crosses Saskatchewan through the day.  After the rain passes the sky clears.  Alberta and Saskatchewan will end up with a sunny afternoon.  The afternoon sun will allow temperatures to peak in the low 20s in southern Alberta, but it will be cooler in Saskatchewan and Manitoba, with highs ranging from 15 to 20 degrees.

Tuesday:

A massive ridge of high pressure centered over Utah will clear out the Canadian prairie sky, except for northern Manitoba.    No significant weather is expected, and it will be warm.   The map below shows expected temperatures in the late afternoon Tuesday:

Wednesday:

Wednesday will be another trouble free day.  The high pressure ridge will begin to move east, but very slowly.   The prairies will remain under a clear sky.   In fact, it just may be cloud-free all the way from Pincher Creek to Lake Huron.    And, that means it will be another very warm day with temperatures in southern Alberta and southern Saskatchewan approaching 30 degrees:

Thursday:

Things change a bit Thursday, as a surface low in the Northwest Territories drags a weak cold front across the prairies.  That’ll produce some early morning rain across the province, with the greatest amounts falling near Grande Prairie and across northwestern Alberta.   In central and southern Alberta, the rain will move through so quickly that accumulations will be minor, and inconsequential.  Wind will continue to be an issue throughout the day, particularly in southern and southwestern regions.    The front will drag the rainfall into Northern Saskatchewan in the afternoon and northern Manitoba in the evening.   Behind the front,  Alberta cools off, but the rest of the southern prairies will still be sunny, dry, and warm:

Friday:

A strong westerly flow at both the surface and aloft will continue to keep the prairies dry.   Southern Alberta may see chinook cloud, especially early in the day.   While it may be windy, no precipitation is expected across the prairies, or for that matter, between British Columbia and Quebec.   And now that the Thursday cold front is long gone, it warms up again in southern Alberta and southern Saskatchewan:

Saturday and Sunday:

The upper ridge of high pressure that gave us the warm and dry weather during the week finally moves on,  to be replaced by an upper trough of low pressure, right over Alberta.   Expect gradually lowering temperatures and increasing cloud over the weekend in Alberta and Saskatchewan, with rain to develop on Sunday in the southern half of both provinces.   Manitoba will remain dry for one more day.

EVENT FORECAST

Touch-a-Truck,  Saturday, September 28, Opasquia Agricultural Society and Exhibition Grounds. The Pas, Manitoba
Mainly sunny, high 20

And, just for fun…..where will it snow this week?

COMPARE TO LAST REPORT:Prairie Weather this Week: September 16