Another Alberta Clipper system is racing eastwards across the Prairies and will bring another shot of snow to Southern Manitoba today.
Snow. Total 2-4cm.
-13°C / -20°C
Riding along the strong northwesterly jet stream that’s been in place over our region over the past few days, another clipper system will race across Southern Manitoba today. This system will prove to be slightly more challenging than Monday’s clipper system as it looks to be more compact and intense. When these two aspects combine, it always proves to be a tricky forecast; small changes in the track of the system (for example, even a shift of 25–30km north or south) can result in dramatically different weather for places along the edges of the track.
The low will slice across northern portions of North Dakota before diving into central Minnesota this evening. The heaviest snow should run just north of this low track with 5–10cm on the ground by the evening. Accumulations will drop off quite quickly to the north of this band which is, of course, where Winnipeg will sit. As seems to be near-climatological wizardry, Winnipeg will yet again sit right on the edge of heavier snow, making the forecast quite sensitive.
The most probable outcome today will look something like this: snow will push into Winnipeg early this morning and intensify fairly quickly. The heaviest snow will mid-to-late morning, and we’ll pick up a fairly quick 2–4cm of snow. It will start to taper off quite quickly after noon, with some lingering light snow lasting through into the evening. Like Monday’s system, there is a chance that the light snow could add another cm or so to the totals for the system. If this system tracks a little further north (even 20–30km), it’s entirely possible that we’ll see another 5–8cm of snow here in Winnipeg. We’ll provide some updates as soon as we can more definitively say which outcome is going to happen.
To the south of Winnipeg, snow will last through more and more of the afternoon the further south you go with accumulations increasing. For communities close to the international border such as Altona, Gretna and Morden, as much as 8–10cm of snow may be on the ground by the end of the day. Winds should remain light enough that blowing snow should not be an issue through the valley today. Things will clear out this evening with some lingering cloud left behind as we head to a low near –20°C.
Thursday
Mix of sun & cloud.
-16°C / -19°C
Thursday will bring a mix of sun and cloud and a high just a few degrees cooler than the day before. Instead of plunging back into the deep freeze like we normally do after many clipper systems, this one is embedded within a larger warming pattern; the highly meridional flow[1] we’ve had lately is slowly being modified and forced into a more zonal flow[2] by a developing complex of low pressure systems over Alaska. Temperatures will climb to around –16°C today and drop only a few degrees tonight as a southwesterly flow aloft kicks in and starts pushing warmer air over our region.
Friday
Mix of sun and cloud.
-6°C / -13°C
We’ll transition into the milder air that we’ve been advertising would be on it’s way by Friday. A solid southwesterly flow aloft will help push temperatures up to around –5 or –6°C across the Red River Valley under a mix of sun and clouds. This warmer weather will continue through the weekend, with highs generally between –5°C and –8°C with overnight lows dropping just below –10°C.
- A meridional flow is one that has a larger north-south component than east-west in the flow directions. In Winnipeg, meridional flows often bring in bitterly cold air in the winter (from the north) and oppressively hot weather in the summer (from the Gulf of Mexico). ↩
- A zonal flow is one that whose east-west component is greater than it’s north-south. Zonal flows tend to moderate temperatures across the Prairies as mild Pacific air washes out the colder Arctic air. ↩
