Monday, January 12, 2015

A break in the deep freeze this week..

Temperatures will be on the rise this week over southern Manitoba as the upper weather pattern allows a milder Pacific airmass to spread eastward across the Prairies.  As a result, the minus 20s and minus 30s of the past two weeks will give way to more moderate temperatures, likely reaching -5C or higher by Thursday.  In the meantime, we have another cold night ahead with temperatures remaining steady near -23C tonight with southerly winds of 30 km/h giving windchills in the mid -30s into early Tuesday morning. Temperatures Tuesday will finally be edging upward with temperatures near minus 12C by evening, although the day will see brisk southerly winds of 30 km/h or more through midday before easing by evening. Wednesday will see a clipper system tracking through central Manitoba bringing a band of snow mainly through the Interlake regions, although Winnipeg will likely see a band of snow through midday of perhaps 1-2 cm. Note that the snow will be accompanied by gusty south winds to 50 or 60 km/h, so reduced visibilities in snow and blowing snow will be an issue in the RRV as the band of snow moves through. Behind the snow, winds will shift into the west as the clipper tracks east, allowing milder temperatures over southern Saskatchewan to spread into southern Manitoba by afternoon and evening. Look for temperatures to rise to -3C or so in Winnipeg Wednesday night as southerly winds shift into the west.  After a mild start, Thursday will see slightly cooler conditions move in (but still above normal) as we get "backdoored" by a cool front thanks to NE outflow winds from a colder high pressure area over northern Manitoba. This will be followed by another surge of milder air over the weekend, possibly preceded by another band of snow Friday.  All in all, a change to milder weather on the way this week, but a bit of a roller coaster ride as periodic clipper systems move across the Prairies.

Thursday, January 01, 2015

A snowy start to 2015

24 hr snowfall estimates from WPC ensemble (inches)
to midday Saturday. Heaviest snow expected
mainly south of Winnipeg through Friday night
December finished with well below normal snowfall in Winnipeg with only 7.2 cm of snow recorded during the month (as observed by the Charleswood climate station)  This would rank as the 16th least snowy December in Winnipeg since records began in 1872.  Snowlovers have been anxious for some significant snow to fall across southern Manitoba as weather systems have been few and far between so far this winter season. But it looks like our first significant snowfall since late November is on its way across southern MB as a fairly intense clipper system tracks across southern SK into North Dakota Friday into Saturday. Snow from this system will spread across southwest MB Friday afternoon and into Winnipeg/RRV by Friday evening. Snow will be falling moderate to heavily Friday night with snowfall rates of 1-2 cm/hr at times before tapering off Saturday morning. At this point, it looks like the system will be bringing a wide swath of 10-20 cm of snow along and south of the TransCanada highway, with the heaviest amounts over southwest MB through the southern RRV into SE MB. For Winnipeg, it looks like we'll be seeing around 10 cm of snow Friday night with lesser amounts to the north of the city, and higher amounts to the south. In addition, northerly winds will be increasing overnight into Saturday morning giving areas of blowing and drifting snow especially outside the Perimeter and into the southern RRV. As a result, expect poor driving conditions Friday night into Saturday across the Red River valley into North Dakota and Minnesota. (NWS has posted winter storm watches and warnings for northern ND and northern MN due to this system)