A system moving through the Northern Plains of the United States will push snow northward across the international border into much of Southern Manitoba, with warning-level amounts in some areas close to the International Border.
Heavy snowfall occurring in Montana is pushing east-northeastward into southeastern Saskatchewan and Southern Manitoba. Heavy snow giving near zero visibilities at times is expected to develop in southern regions near the international border, including the Melita, Pilot Mound, Morden/Winkler, and Emerson regions. Environment Canada has issued Snowfall warnings for the Melita and Pilot Mound/Kilarney regions, with 10cm of snow expected in areas close to the border, and the potential for amounts in excess of 15cm in upslope snowfall areas of Pilot Mound. All sorts of warnings exist for most of North Dakota, so anybody who has to travel south today should take extra precautions and prepare for extremely poor driving conditions.
For Winnipeg, the snow will push into the city mid-to-late afternoon and stick around for 18-24 hours. Thoughts based of previous model runs would have been for just some light non-accumulating snow, even taking into account that all models were keeping this system too far south. The new GEM-REG run has, however, pushed the system (in my opinion, correctly) further North and is bringing more substantial snow into the Winnipeg area.
GEM-REG 24H Cumulative Precipitation valid 12Z Tuesday 21 Dec. The heavier snow expected along the International Border and through North Dakota is the dark-ish green shading, indicating 7-10mm of liquid equivalent precipitation. This covers Monday morning to Tuesday Morning.
While we won’t deal with the extremely poor traveling conditions of our neighbours to the south, we will see accumulations of 2-4cm when all is said and done. South of the city, amounts of 5-10cm should pile up. The bulk of the precipitation will pull out of the province overnight, however there will be a weak trough that hangs back through the RRV and southeastern Manitoba that will continue to produce light snow through much of the day tomorrow.
GEM-REG 24H Cumulative Precipitation valid 00Z Wednesday 22 Dec. This shows the precipitation expected to occur Monday evening through Tuesday evening. Light snow, without significant accumulation, is expected to occur through much of southern Manitoba through the day on Tuesday.
After this system, we should have a fairly pleasant rest of the week, with highs just above or near -10C and lows in the low minus teens.
Another small point of significance to this event is that it may be one of Winnipeg’s last chance to break the record for wettest year ever. The current record is 723.6mm from 1962. We currently sit in 3rd wettest year ever at 716.0mm, with second place only a hair ahead of us at 718.4mm (which was from 1953). We need only another 7.7mm to break the record, and this system, in a worst case scenario could give us something in the 4-6mm range.
Worth noting, is that in many of the wettest years ever, a major flood did not occur in the following spring; just shows how the melt rate and spring precipitation are the most crucial aspects in our annual floods.