An upper-level trough will move fairly quickly across the Prairie Provinces tomorrow into early this week. As it does so, it will induce lee-cyclogenesis at the surface in the Wyoming/western South Dakota area. This will set the stage for a quick burst of snow across parts of Manitoba and possibly North Dakota on Wednesday and then again on Friday. Below is a combination of different models, which very consistently show a low pressure forming in South Dakota:
As is usually the case with these types of systems, the position of the low will be critical. Temperatures on Tuesday will be too warm for snow and therefore rain is expected to fall. However, Tuesday evening and Wednesday early morning, a changeover to heavy wet snow is expected. Below is an example of the precipitation change:
While this doesn't not seem like a lot of precipitation, a strong deformation zone is observed on forecast models extending from the North Dakota low to parts of southern Manitoba. This axis will likely see enhanced snowfall rates and boost local amounts across Manitoba. Forecast models are having difficulties in providing the exact amount of snowfall and several things need to be taken into consideration for this event:
Rain prior to event will cause snow to melt more rapidly on contact, therefore decreasing snowfall totals;
Temperatures might hoover around the 0C mark a bit too long, preventing much snow from reaching the ground and
The exact track of the low is still unknown, a more northerly track would favour longer rainfall duration and therefore a later changeover to snow, which would ultimately limit snowfall totals.
Considering all of these factors, we have placed our fairly conservative snowfall forecast below:
Wednesday April 1st, 2020
Threat level: LOW TO MODERATE
Confidence: MODERATE TO HIGH (based on model agreements)
Expected hazards: SNOW // BRIEF WHITEOUTS // TRAVEL IMPACTS
Expected snowfall: 10-20cm
Locations impacted: southern Manitoba
Expected watch: special weather statements and snowfall warnings
Most likely areas impacted: cities in south-central Manitoba (Portage La Prairie, Ste. Claude, Morden/Winkler, Carman, Elie, Souris and vicinity)
Surface winds will not be particularly strong on Wednesday, so some brief whiteout conditions are possible, but not up to winter storm or blizzard criteria. We will be updating this post as new information becomes available.
Friday April 3rd, 2020
Threat level: LOW
Confidence: LOW (based on model agreements)
Expected hazards: SNOW
Expected snowfall: 5-10cm
Locations impacted: southern Manitoba
Expected watch: special weather statements
Most likely areas impacted: cities in south-central Manitoba (Portage La Prairie, Ste. Claude, Morden/Winkler, Carman, Elie, Souris and vicinity)