Arctic Assault on Winnipeg

While we had a glimpse of how absolutely wonderful it will be for summer to be here over the past few days as temperatures shot up into the mid-20’s, the spring-that-never-ends is making an ugly return as multiple shots of Arctic air invade the Southern Prairies.

Arctic air invading the Southern Prairies

Cold Arctic air blasting south over the Prairies. Image from the NAM valid at lunchtime today.

Temperatures through the remainder of the week are going to go from below-normal to more-below-normal as the above pictured cold front continues to slump southwards. The cooler weather was ushered in overnight as the cold front passed through Winnipeg bringing strong, gusty northerly winds. Temperatures today will only climb to around 13°C with strong northerly winds gusting as high as 60km/h. Temperatures will dip down close to the freezing mark under clear skies tonight with widespread low temperatures of around 2°C.

Wednesday

13°C / 2°C
Clearing & windy from the north.
Thursday

15°C / 5°C
Mainly sunny.
Friday

12°C / 0°C
Cloudy with chance of late-morning showers. Clearing in the afternoon.

The rest of the week won’t fare much better. Temperatures will try to climb a little closer to normal tomorrow with highs reaching around 15°C. The low tomorrow night will be a little milder at around 5°C as some warmer air is pushed over the province ahead of an intense low pressure system working it’s way out of Alberta through Saskatchewan.

Friday will be fairly cloudy as yet another cold front sweeps through the Red River Valley. There may be a few showers along the cold front as it pushes through in the late morning and early afternoon, but only a couple mm of rain would be likely to fall, if any. Northerly winds in behind the cold front will clear the skies but limit our high as colder air is ushered in yet again. Overnight lows will drop close to 0°C on Friday night under clear skies.

Long-Term

A cold weekend is ahead of us as we move even deeper into the Arctic air mass. Saturday will be the coldest day with daytime highs only in the mid-to-high single digits with another night with temperatures at or just below 0°C. Conditions will improve on Sunday as the coldest air moves off to our east and the daytime high rebounds into the mid-teens.

At this point, it’s looking like we’ll be in for a huge turnaround early next week. Very warm air is expected to flood across the Prairies as an upper ridge begins building in. At this point it looks like we will start off next week with daytime highs rocketing back up into the mid-20’s. At this point it looks like 24 or 25°C is entirely possible with a slight chance we’ll see temperatures climb into the upper 20’s. The large-scale pattern shift looks like we’ll be moving into a more stable warm pattern, so just make it through the next 5 days and we’ll be enjoying summer!

Cooler Weather Returns

After a few days of tasting what actually amounted to seasonal weather, we’ll be back into a below-normal temperature regime through the rest of the work week. With little precipitation expected over the next few days, when will the warm weather return?

850mb Temperatures on Thursday Afternoon

850mb temperatures reveal a significant cold trough (blue colors) that will sit over Central North America bringing cooler temperatures to our region.

A rather strong Arctic high pressure system is building into the Prairies behind yesterday’s low pressure system that brought significant amounts of snow the Manitoba Parkland & Interlake regions while dumping 20–30mm of rainfall over the Red River Valley. While massive amounts of snow cover were lost over the weekend, portions of Western & Central Manitoba are looking decidedly whiter after as much as 30–40cm of snow fell on Monday and Tuesday.

Wednesday

1°C / -5°C
A few flurries tapering off this afternoon. Clearing overnight.

Here in the Red River Valley, the bulk of the precipitation fell as rain before switching over to light snow in yesterday evening. This morning we’re left with some flurries that, fortunately, shouldn’t really amount to much as they’re being formed in some lingering instability left behind the low pressure system that’s now pushed offshore into Hudson Bay. As the Arctic ridge builds in through the day, the increasing stability will slowly quash any remaining flurries. Temperatures will drop to around –5°C tonight as the cooler air continues to filter into the southern portions of the province.

Thursday & Friday

We’ll see the main axis of the Arctic ridge push through on Thursday which will keep our temperatures some 15°C below normal with a daytime high of only around 1°C under sunny skies. It will be another chilly night with overnight lows close to –5°C.

Thursday

1°C / -4
Sunny.
Friday

8°C / -1°C
Mainly Sunny.

With the ridge past us on Friday, milder air will begin to push back into the region. We can expect just a few clouds and temperatures beginning to climb back towards normal, but only topping out at around 8°C. The overnight low on Friday night will dip just below the freezing mark.

A Look To The Weekend

This weekend looks quite pleasant with temperatures rebounding back into the mid-teens. A weak cold trough aloft is expected to linger near the region, so our temperatures may end up in the low-teens instead of the mid-to-high teens if it ends up setting up a little further west or north than currently forecast. While a potent system looks to affect Grand Forks & Fargo through the weekend, current indications are that this system will stay well to our south, just pushing some light cloud cover into the Red River Valley & SE Manitoba. There’s a slight chance areas in extreme SE Manitoba, such as Sprague, may see a light shower or two through the weekend.

Week to Start Cool, but is Spring Coming?

This week will start out well below normal, but there are signs that we may begin to warm up towards week’s end. Is Spring finally set to arrive?

Monday and Tuesday

Monday
image
Mix of sun and cloud. Chance of flurries.
-3°C / -8°C
Tuesday
image
Mainly sunny.
2°C / -8°C

Monday will be a cold day by April standards. High temperatures are generally not expected to exceed the freezing mark in Southern Manitoba (except in cities and forests), which will make the day some 15 degrees below our normal high of 13C. There may be some isolated flurries on Monday, as weak low-level instability develops during the day.

Tuesday will be a bit warmer than Monday, but not by much. Temperatures should climb just above zero in most areas, but that will still put as well below normal.

Wednesday

Wednesday
image
Mainly cloudy. Chance of flurries.
2°C / 2°C

Wednesday should be another above freezing day in Southern Manitoba, but we could see more snow as well. Flurries look to plague us for much of the day as the atmosphere once again destabilizes behind a passing weather system. Accumulations look to be minimal, but I doubt that will make the snow any more pleasant.

Long Range

image

Forecast high temperatures on Friday

There are signs that we may finally see a return to near normal or just below normal conditions by late this week or into the weekend. Models are in fairly good agreement that temperatures will rise up into the high single digits or low DOUBLE digits by later in the week/weekend. Of course we have seen forecasts like this fall apart before this spring, but hopefully this time things will be different.

Pleasant Weekend With Stormy End

Although temperatures will remain well below normal, we’ll see a pleasant weekend ahead when compared to the weather we’ve had as of late.

Friday

4°C / -14°C
Sunny.
Saturday

2°C / -4°C
Increasing cloudiness in the afternoon.
Sunday

2°C / -3·C
Cloudy; rain or snow beginning midday.

The next two days will be fairly nice despite the cool air that remains entrenched over the province. Both Friday and Saturday will provide plenty of sunshine and daytime highs climbing a few degrees above zero. We should see substantial snow-melt here in Winnipeg over the next two days thanks to that increasingly strong April sun. We’ll see a cooler night tonight as winds lighten up allowing us to radiate more heat away than the past couple nights. Temperatures will likely drop into the minus teens tonight while cloud cover will keep us substantially warmer on Saturday night.

Stormy Sunday

Precipitation totals for the daytime period on Sunday from the 00Z April 19 GDPS model.

For Sunday, an Alberta Clipper will make it’s way across Southern Manitoba and while many aspects of the system look to be relatively innocuous, it looks poised to pack a punch precipitation-wise. Snow will push into the Red River Valley midday, but the afternoon brings a particular challenge. Warm air will be advected northwards in the southeast flow ahead of this system, slowly warming the lower-levels of the atmosphere. Some indications are that preciptiation will switch over to rain in the afternoon, especially for the central Red River Valley and areas eastwards. It’s a very challenging problem and the phase of the precipitaiton will make a significant impact: around 10mm of liquid-equivalent precipitation and if it ends up falling as snow, that could quickly amount to another 6-10cm of the stuff. It’s almost a certainty that areas east of the Red River Valley will see mainly rain and areas west of the Red River Valley will see mainly snow.

At this point I think we’ll end up seeing a mix here in Winnipeg, with predominantly snow in heavier areas of precipitation. I’m not going to wager too much on accumulations right now; it’s likely that much of the snow will melt on contact with the ground as temperatures will likely remain just over the freezing mark. The system will move off overnight leaving clearing skies on Monday morning.