Friday, March 31, 2017

March goes out like a lamb in southern MB.. Winnipeg records 7th least snowy March on record

March 2017 will go down in the record books as the 7th least snowy March in Winnipeg in 145 years of records. Only 2.4 cm of snow fell during the month, compared to the "average" of 16.5 cm that usually falls in March. That comes as a relief to residents of the Red River valley after heavy snowfall in December increased fears that a potentially major flood situation would arise in the Red River valley come the spring melt.  A wet fall, soggy soil conditions and a heavy snowpack were leading to an elevated flood risk throughout the valley, contingent on late winter and spring precipitation.

Top 10 least snowy Marches
in Winnipeg
Thankfully, precipitation has been mainly light over the past few weeks in the Red River valley, and a major winter storm that clobbered much of western Manitoba earlier in the month largely spared the valley. Overall, the month of March finished with 14 mm of total precip at YWG airport (17 mm of rain at my site + 2.4 cm of snow) Normal March precipitation is around 24 mm (composed of about 10 mm of rain and 17 cm of snow)  so March precipitation was below normal. Snowfall in February was near normal with only 12.2 cm for the month. In fact, in the 11 weeks since Jan 10th, only 22 cm of snow has fallen in Winnipeg compared to 90 cm in the 6 weeks between Dec 1st and Jan 10th. That has led to a significantly reduced snowpack in the valley, which has gradually disappeared over the past 2-3 weeks.  The reduced snowpack and gradual thaw were ideal conditions to ease the Red River flood threat this spring although mild weather over the past few days has led to some local flooding due to ice jams. The Red River is expected to crest in the Emerson area sometime next week as a "moderate" flood which will gradually progress north over the following days. More major flooding is expected over western MB in the Souris and Assiniboine watersheds where they have had more snow.  

What about April?

So with only 2 cm of snow in March, does this mean winter is over? Well, for the most part.. yes. Now that snowcover has disappeared, it will be easier for the ground to warm up since snowcover acts to reflect heat. But that doesn't mean we won't see any more cold weather or snow. A look at past Aprils in Winnipeg shows that since 1872, only 8 Aprils have not seen ANY snow during the month (not even a trace). 95% of Aprils have seen at least a trace of snow, and more than half (56%) have seen at least 5 cm of snow. So although snow is currently not in the forecast, it would be highly unusual to go the entire month of April without seeing at least some snowflakes at some point. Hopefully, April 2017 is one of those months with little or no snow. 

Chart showing odds of snow in Winnipeg during April 

April snowfall stats for Winnipeg:

- Normal April snowfall: 10 cm (but highly variable year to year) 
- Normal days in April with measureable snow (>= 0.2 cm): 3
- Odds of at least 1 day in April with a snowfall >= 2 cm: 67% (2 out of 3 years)
- Odds of at least 1 day in April with a snowfall >= 5 cm: 41% (2 out of 5 years)
Odds of at least 1 day in April with a snowfall >= 10 cm: 17% (once every 6 years)
- Snowiest April on record: April 1997, 48.6 cm (year of the big flood)     
- least snow in April:  0.0 cm (8 years;  last occurrence was April 1998)

Graph of April snowfall in Winnipeg shows how variable it is year to year.
Snowy Aprils are just as likely as snowfree ones in any given year
(graph from @jjcwpg) 


  1. Nice dry week ahead with no major systems expected through Saturday. After a bit of a cooldown today and tomorrow, things warm up nicely for the end of the week, with temps likely reaching mid teens by Friday and upper teens possible Saturday (chance of the seeing the season's first 20C in some spots)

    Things turn more unsettled as we get into Sunday and Monday as a Dakotas low spreads precip over ND into srn MB. Models have been all over the place regarding how much precip, if any, will fall over Winnipeg and the RRV.. with some runs suggesting 15-25 mm, others saying a complete miss. There's also a possibility of seeing some measurable snow on the backside of the system Monday into Tuesday.. but again, not a lot of consensus on that right now. All models do agree we get much cooler early next week (but not for a prolonged period) So at this point, all we can say is there's a system that bears watching for Sunday into early next week that has the *potential* to bring some rain and wet snow to parts of the RRV. Any further details will have to wait until there's better model agreement.

  2. Rob. I've been hearing a lot of talk about significant SNOW coming Sunday night. None of the apps show it yet but a lot has been going around saying that we could get up to 15cm. Are you thinking it'll be a rain event or a snow event?

    1. Looks like neither at this point. System will be developing well to our south, so we shouldn't see any precip from it. Before that, a system will track through central MB Saturday with a band of rain mainly though central and nrn MB. So basically, srn MB misses both precip events over the next few days.