|NAM model showing surface temperatures (F)|
Wed morning. Arctic high building in from Saskatchewan
will bring in mid winter cold over southern MB
For tonight, a weak clipper system that has been bringing some light snow across southern MB today will exit the province, with gradually clearing skies tonight from the north. This will allow temperatures to drop well into the minus 20s by Wednesday morning, with some spots in the northern Interlake likely hitting the -30C mark (Moosehorn, Grand Rapids, Berens River, Swan River, etc) In Winnipeg, temperatures are forecast to drop to -26C overnight with light northwest winds creating wind chills near -35 for the morning commute. Temperatures will recover only to around -18C Wednesday under sunny skies, some 13C below normal for late November. Wednesday night into early Thursday will be downright frigid in Winnipeg and the RRV as the core of Arctic ridge crosses the region. That will allow temperatures to plummet towards the -30C mark even in Winnipeg Wednesday night into early Thursday morning.. so make sure you have those block heater cords ready and working! (For the record, the earliest that Winnipeg has hit -30C or lower was on November 19th in 1896 with a reading of -33.9C. Record low for Thursday (Nov 27th) in Winnipeg is -36.1C in 1891, and more recently in Nov 1985, the airport had 5 days of -30C or lower over the last week of November. So believe it or not, it has been worse at this time of year)
A slight moderation is expected by Friday as the next clipper system moves in with some light snow, and high temperatures near minus 10C. Unfortunately, it looks like we're back into the deep freeze over the weekend into early next week behind the clipper system. There are some signs that the abnormally cold pattern will relax a bit by the middle to end of next week, but we'll have to see if those moderating signs continue over the next few days. Until then, bundle up and get prepared for some mid winter cold.. in November!
Meanwhile, it was 21.3C yesterday in Huntingdon, Quebec. That gave a small humidex of 23... a week before December.ReplyDelete
As of 10 pm this evening.. Grand Rapids already down to -31.4C and Swan River at -29.9C. Gives an idea how cold that Arctic ridge is. Not too happy that we're seeing these kind of temps in November already!ReplyDelete
By the way, just crunching some numbers.. and it looks like this November will end up at around -9C in Winnipeg, about 4C below normal and our coldest November in almost 20 years (since 1996). Looking at Decembers that followed a November similar in average temperature to this year reveals that 75% were followed by a colder than normal December with a mean average around -16.5C.. about 3C below normal. About 20% of Decembers were milder than normal so there's a slight chance that things could turn around next month.. but odds aren't good. There are signs that the stubborn west coast ridge is going to hold through the winter (more or less) which would put us in a deep mid continent trof allowing frequent invasions of Arctic airmasses through the winter. Yes, that's what happened last year.. but it's impossible to say if this year will be as severe or persistent. For our sakes, I hope not..ReplyDelete
-28C temperature with a -36 windchill in Dauphin. Brutal.Delete
10 -15 cm next Wed!!!! Rob is this for real??ReplyDelete
I wouldn't get over excited with that one yet.. it was only the GLB model showing that, and it has backed off on those amounts on today's runs. Ensembles and Euro not showing much at this point for Wed, so we'll keep on eye on how things develop.Delete
In the shorter term, models are coming around for more significant snow for us in the Friday night to Saturday period with some overrunning Pacific moisture over cold air. Most are showing QPF amounts in the 5 mm range which could easily result in amounts of 5-10 cm given cold air in place. Before that, looks like we may get 2 or 3 cm from a minor clipper system Thursday night. So looks like things will be getting a little whiter here by the weekend..
Will be interesting to see how cold Winnipeg airport gets tonight with arctic ridge building in and then sliding off to our south overnight. Airport barely made it above -20C this afternoon with a light NW wind, and those temps will plummet quickly this evening once we lose the sun. We maintain a light NW drainage wind at the airport until midnight which is favourable for rapid cooling at the site, before wind direction gradually swings around to the southwest then south overnight, but still very light wind speeds. That should stop the airport from plummeting below -30C, but it's possible they'll hit the -30C mark by midnight or 2 am before temperature stabilizes and even rises slightly overnight as winds swing into the south off the city. That will still allow places near and outside the perimeter to drop close to -30C overnight as well, including my site in Charleswood.ReplyDelete
Last night, the airport dropped to -29.6C, about 3-4C colder than guidance suggested because of that cold bias at the airport with a light NW drainage wind. Guidance tonight is only showing about -25 to -27C for Winnipeg, which will be too warm given the light NW drainage wind expected through midnight. RAP is suggesting a low of -30C by 4 am before temps level off. If the airport does hit -30.0C or lower tonight, it will be the first -30C reading we've had in November since 1985, almost 30 years ago. (although we did hit -29.7C in Nov 1996)
Temperature already down to -22.5C at YWG airport at 5 pm. RDPS guidance had YWG going down to -22C by 6 pm then steady the rest of the night with a a low of -23C by 6 am. Clearly not catching onto history of temps in this ridge, and local effects of light NW flow at YWG airport through midnight.Delete
Temperature not dropping as much at YWG airport this evening as winds have pretty much gone calm or starting to swing into the SW.. which is minimizing local drainage effect. YWG dropped to -26C earlier this evening and has remained fairly steady since then. We'll possibly drop a couple more degrees over the next few hours but that -30C mark looks less likely at this point. Some -30C readings however are being reported outside the city and scattered through southern Manitoba as of 11 pm. Coldest I find is -32C at Ethelbert between Dauphin and Swan River.Delete
Looking at mesoanalysis.. 850 and 925 hPa temps are around -22 to -23 C. With meager snowcover (2 cm), hard to believe you could develop enough of an inversion (with modification of airmass during the day) to get down to -30 C regionally. As Rob says, will be interesting to see region-wide lows in the morning.ReplyDelete
An official low of -29.5C at YWG airport early this morning, which must have occurred just after midnight since temperatures were pretty much steady near -26C the rest of the night as winds swung around to the south. So not an official -30C reading at the airport.. although close enough.ReplyDelete
Attention now turns to snow chances over the next couple of days. Weakening clipper from Saskatchewan brings in some snow tonight over southern Manitoba, with about 5 cm possible over SW MB, but only a cm or two expected for Winnipeg overnight. A second stronger clipper tracks through North Dakota Friday into Saturday, spreading more extensive snow across southern MB. Right now, model concensus generally indicating about 5-8 cm of snow possible for Winnipeg by Saturday with the bulk of it falling in the Friday evening to Saturday morning time frame.
Missed out on the light snow last night with nothing in Winnipeg.. although they got 1-2 cm over the Winkler and Emerson areas and 3-6 cm over SW MB. Next wave of snow coming in from the NW today, which we won't miss. Looks like snow picking up through the afternoon into this evening, and persisting tonight into Saturday morning. About 5-10 cm possible for Winnipeg.. with more to the north of the city, less to the south.Delete