|6-10 day outlook valid Dec 10-14|
showing massive warmup over
central North America (CPC)
For those already tired of the mid winter-like cold that has gripped southern MB and the Prairies much of the past 3 weeks, some good news is on the way. A major shift in the weather pattern next week is expected to bring a prolonged period of above normal temperatures across much of the southern Prairies and central North America through next week. We'll get a taste of the milder weather on Sunday as a weather system tracks across southern Manitoba bringing a southerly flow of milder air across the south, with temperatures likely climbing towards the freezing mark in Winnipeg and slightly above freezing over parts of western MB. We'll get into some briefly colder air on Monday behind this system, but the colder weather will be short lived as a massive influx of Pacific air spreads over the Prairies beginning Tuesday. This flow of warmer Pacific air will overspread southern Manitoba by mid to late week, sending temperatures in Winnipeg and the RRV above freezing from at least Thursday into Saturday. In fact, some downslope areas from Dauphin through McCreary to Portage La Prairie, Morden and Winkler may see temperatures of +7-10C by Friday. That will result in considerable melting of the meager snowpack across southern Manitoba.. with areas of bare ground likely re-appearing by the end of the week in parts of the RRV and SW Manitoba. So put away the block heater cords for awhile and stock up on the washer fluid.. warmer weather is on the way!
Hi Rob, any chance Environment Canada's +7 and +8 for this Thursday and Friday could actually happen?ReplyDelete
+8C is probably a bit optimistic for Winnipeg given an expected southerly valley wind here Thursday and Friday, but I think a few places in the western RRV and SW MB will hit +8C or even +10C by Friday, in those favourable downslope areas (such as Dauphin, McCreary, Boissevain, Portage LP, etc), forested areas, and any areas that will have lost their meager snowcover by then. For Winnipeg to get +8C we'd have to get a westerly-SW wind that would tap the very mild temps out west and surface with a favourable downslope wind. That *may" happen, but at this time, I'd be going with a more conservative +5C for Winnipeg for late week.. which is wonderful after last week! Will be very interesting to see how mild some of the more traditional warm spots get later this week, given 850C temps of +10C or more, and minimal snow cover. Some record highs quite possible..Delete
Those gusty south winds Tuesday and Wednesday will certainly temper the warm-up in the RRV, so even if we get to minus 2 or so by Wednesday, it will feel chillier with those brisk winds. Hopefully, the southerly winds won't be as strong Thursday and Friday to enjoy those milder temps.Delete
This will be one of those times I wish Winnipeg was at 5000 feet elevation.. to enjoy those +15C temps by Friday! :)
If January/February turn out to be cold, this could be bad news for water pipes. Bare ground followed by Arctic cold is a good setup for deep ground frost penetration. But if Jan and Feb are also mild, then there's nothing to complain about...ReplyDelete
By the way.. record highs for Winnipeg for later this week..ReplyDelete
Thu Dec 11 ... +9.4 (1913)
Fri Dec 12 .... +5.0 (1877)
Sat Dec 13 ... +6.7 (1895)
If we break any records, Friday would have the best chance at +5C. By the way, 1913 and 1877 both had very little snow in December, and in fact were both noted for having brown Christmases in Winnipeg. Dec 1877 was the warmest Dec on record. The 1895 record however was preceded by a cold snowy start to December with 30 cm of snow over the first 11 days of the month. So it is possible to get to +6 or +7C in Winnipeg with snow on the ground, although ideally you would need a westerly wind to tap warm Pacific air and get it to surface.
Based on the forecast three days out by EC, record high minimums are possible too.Delete
EC going with +8C for Thursday, +3C for Friday, and a whopping +10C for Saturday based on latest forecast for Winnipeg this morning. That +8C for Thursday is likely too high by about 5C, and +10C for Saturday? Is it possible? Well.. a couple things need to happen. One, we lose a lot of our snowcover by then.. and we get a SW surface wind with sunshine, or a SE wind to downslope off the higher terrain to our southeast. No other guidance going with temps that high at the current time with high temps generally forecast in the +2 to +5C range for Winnipeg Thu-Sat. Slight chance we could see +5 to +7C or so Friday and Saturday with favourable winds and sunshine. Will be interesting to see what actually happens..Delete
I'm at a loss to to explain where that +10C for Saturday came from. That forecast is an automated forecast straight from the GLB model, and it shows only +3C in Winnipeg for Saturday afternoon. So there must be some statistical post-processing to bump that high up to 10C. But adding 7C seems a bit extreme in this case. GLB is showing we get a bit of a E-SE surface wind Saturday which may bump us a bit to +5c or so with sunshine.. but +10C seems highly unlikely given the setup. Likewise, that +8C for Thursday seems artificially inflated.Delete
The other fly in the ointment will be the potential of low cloud spreading into the RRV and getting stuck under the strengthening inversion as 850 mb temps rise into the teens. There's already an extensive area of low cloud over Minnesota that has spread into the GFK area this afternoon, and with a southerly flow for the next few days and the potential for some melting of the snow pack, that will increase low level humidity. That would seriously jeopardize those sunny warm forecasts for Winnipeg over the next few days.Delete
In case you're wondering about how warm it can get in December in southern Manitoba... consider these records..ReplyDelete
Warmest December day in southern MB was Dec 6 1939 when it hit 17.8C in Melita, Waskada and Morden thanks to a very mild December and snow free ground. Winnipeg hit its all time December record of 11.7C that day. 1939 would go on to be one of the warmest Decembers on record, and was also noted for its green Christmas that year.
Dauphin hit 12.3C on Dec 14 1997
Warmest Christmas Day in southern MB was in 1999 when it hit 10.0C in Ochre River and 9.7C in McCreary (Ochre River is 1/2 way between Dauphin and McCreary)
The latest Dec warm spell was on Dec 27 1980 when temperatures hit 13C in Pine River (between Dauphin and Swan River), 12C in Ochre River, 11.5C in McCreary, 10.2C in Dauphin, and 9.5C in Portage LP. Winnipeg hit a record +6.4C that day, but not until late evening when winds shifted into the west after blowing hard from the south all day (50G70 km/h) with temps below freezing and blowing snow.
So what does this show? Yes, it can get warm in southern MB in December, and +10C temps are possible, but usually in more traditional downslope areas, and if there's no snow on the ground.
Is the reason that traditional downslope areas in Manitoba increase in temperature more than Winnipeg during warm spells such as this similar to the compressional heating effect provided by the mountains on places like Calgary?
Yes, the effect is very similar to the chinooks they get in southern Alberta, but on a much smaller and localized scale here. You can consider these as "mini-chinooks".Delete
Thanks, Rob. I appreciate the insight.Delete
That mini-chinooking already evident today off the Turtle Mtns with gusty southerly downslope winds already pushing temperatures above freezing in Deloraine (+1.0C as of 1 pm) while most other spots in SW MB are in the minus 5 to minus 10C range. This downsloping effect will become even more pronounced tomorrow with places like Dauphin, Ethelbert and McCreary getting into act with SW downslope winds off the Riding Mtns likely sending temps up to +7C for them. Meanwhile, we'll struggle below freezing here in Winnipeg and the RRV Wednesday thanks to a brisk southerly valley wind.ReplyDelete
By the way, similar downsloping effect in SW SK has sent temperatures up to +11C in Maple Creek SK as of 1 pm today with SW winds off the Cypress Hills.
Well.. so much for a sunny Wednesday. Extensive area of low cloud that was over Minnesota today is spreading into RRV and SE MB this evening, which will likely persist through the night and Wednesday as that low cloud gets trapped under an increasingly strong inversion in that brisk southerly flow with warmer air aloft. That will mean generally cloudy skies tomorrow along with brisk south winds that will keep our temperatures below freezing. Meanwhile, sunshine will be more prevalent over western MB west of the RRV, with temps soaring into the +7-10C range in the usual downslope areas.ReplyDelete
Stratus deck holding firm over Winnipeg/RRV/SE MB today..clearing out west of Elie with sunshine in PLP this morning. Swan River-Dauphin-McCreary areas will be the MB hot spots today, possibly reaching +7C this afternoon. Meanwhile, temps will be struggling to get to -1C or -2C today in Winnipeg/RRV.ReplyDelete
Up to +5.7C in Ethelbert MB (between Swan River and Dauphin) as of 10 am according to MAFRI mesonet.Delete
Well... so much for a sunny Thursday, and Friday, and Saturday...ReplyDelete
Huge area of stratus/low cloud over US plains has surged north back into RRV and SE MB this morning and looks like it will hold firm for the next few days thanks to a persistent south wind and strong low level inversion which will rob us of that nice sunny stretch of potentially record high temperatures. As a result, we'll stay overcast with brisk south winds keeping our temperatures near or slightly below freezing today and Friday, possibly nudging above zero Saturday (but not +10!) In addition, may see some lower vsbys in fog and/or frzg drizzle at times. So although we're still a good 10C above normal these next few days, it won't feel as nice as it could have without all this low cloud in place. Meanwhile, areas west of the RRV will be sunnier and warmer over this time.
I'm assuming EC has meteorologists who predict the weather. Why are they calling for +10 on Saturday? CTV this morning was the same forecast. Yet the WN (who has been right all week with the temperatures) is calling for only 0 on Saturday.
How is this possible that the forecasts are so completely different when it is just 2 days away? People keep saying Sat is going to be so nice at +10 and I keep saying it's not going to happen. Forecasts like this drive me nuts.
This comment has been removed by the author.Delete
I'm not sure where that 10°C is coming from in the first place? Not even the GEM seems to be giving something that high. Do you know where it's coming from Rob?Delete
JJ.. That forecast high of +10C is a MOS-adjusted forecast that comes straight from model output. Basically, that automated forecast looks at model surface temperatures, then adjusts it based on several additional temperature fields and statistical analysis, including temperatures at 925 mb. In Saturday's case, it sees very warm temperatures at 925 mb and adjusts the model surface temperature higher since it assumes some of that warmer air aloft will mix down. Generally, this results in more accurate high temperature forecasts than using straight model surface temperatures.. but in this case, it results in overforecasting the high since there won't be any mixing from aloft.Delete
A human forecaster would be able to recognize this questionable adjustment and remove it, leading to a better temperature forecast (of say zero or +2C similar to what most forecasts are saying for Saturday) However, Day 3-7 forecasts from EC are automated, and are output "as is" straight from the model with no input from human forecasters. That's why you'll often see a major change in the forecast when it goes from Day 3 (computer automated) to day 2 (human adjusted) In that case, you'll likely see that sunny high of +10C for Saturday change to more reasonable temperatures with tomorrow's forecast.
well explained Rob thanks, I never pay attention to EC forecasts, WN by the way is no better, unfortunately though these for the most part are the only 2 forecasts that get publisized all over the news/radio/tv everyday in the city. How are the forecasts from others like underground or weather.com come from output as well? Those forecasts all along had showed highs zero-2 range for this period going back a few days.Delete
Anon.. Various weather forecast services use data from different models and temperature algorithms to come up with their own values. In the case of Wx Underground, AccuWeather, Weather Channel, etc, they would likely use data from American models like the NAM and GFS for their forecasts, which could differ quite a bit from Canadian models (which drive EC forecasts). TWN seems to have the flexibility to use any model guidance they want depending on the situation.Delete
Ideally though, if you're going to automate forecast production, using ensemble model guidance from a variety of models or model runs would be the best way to go (less extremes and flip flopping, more conservative forecasts)
Totally agree, well done thanks again for the info Rob!Delete
Thankyou for your insight and great explanation ! I appreciate your weather discussions and forecasts.ReplyDelete
Our stratus cloud edge is literally just half an hour west of the city. Nice and sunny in places like Elie, Carman, Portage, Morden, etc.. Low cloud has also cleared over Sprague and Whiteshell regions to our east, leaving a sliver of low cloud up the Red River valley. Overall, stratus deck appears to be eroding somewhat, so hopefully we get some breaks tomorrow. But with nighttime coming and winds dropping off with melting temperatures over a chilly snowpack, that will likely only reinforce stratus deck tonight along with areas of dense fog developing.ReplyDelete
Well, record high temperatures may be elusive because of this stratus deck; however, Winnipeg did set a new daily high minimum temperature yesterday of -0.5 C.ReplyDelete
With a low of -1.1C today (Dec 13th), Winnipeg will set another record high minimum temperature. Prev record hi min for Dec 13th was -2.8C in 1894.Delete
Can't wait for a wind shift. This persistent stratus and fog along with the sloppy mess on the streets is getting tiresome and depressing. Never thought I'd be looking forward to colder weather! Hurry up cold front!ReplyDelete
Maybe I'm one of few, but I'll take cloudy and mild for the entire winter than sunny and cold! Cloudiness doesn't actually bother me as long as it's warm :)Delete
By the way, yesterday's old record was in 2002 not 1894 (I think you saw that -2.8°C in 1894 record for Dec 11).
Thanks for the correction JJ.. Yes, I was looking at the 11th..Delete
No I'm with you JJ. I will take the mild even if it costs the sunshine.ReplyDelete
Snow storm next week? Accu and WN showing Monday. Snowy Christmas!!!
I now its early but does this look promising?
Those forecasts are likely based on the GFS and GLB models which show a system tracking through central Manitoba Monday and intensifying over NW Ontario Tuesday, possibly bringing some accumulating snow to Winnipeg and southern MB in that Dec 22-23rd time period. Euro model is weaker on this system with less snow.. Overall, I wouldn't get my hopes up too much at this point. Storm track doesn't look optimal for a good snow event for southern MB, and Euro is not too excited yet. We're certainly due for a good snowfall, as we've only had one snow event with more than 5 cm so far this season in Winnipeg (9 cm on Nov 28-29) but it's possible we're in a developing El-Nino pattern that generally favours less snow for us as systems bypass the southern Prairies. Whether this is a short term thing, or will last the entire winter is impossible to say at this point. But it seems to be that way so far..Delete
whether we get snow or not early next week, it does appear arctic air returns to close out the year. Rob are you still looking forward to that Colder weather? lolDelete
If it stayed like this the rest of the winter (-10/-20), I'd be happy. Going back to -30 weather.. not so much. I'm just happy we're getting through most of December fairly easily. That's one less month of brutal cold to contend with. Although I know there's still a long way to go.. and I'm not expecting us to completely dodge brutal cold spells this winter. Hopefully they're more transitory this year than last winter..Delete
Just as I post that, the Euro has come in today a bit stronger on the system for next Monday-Tuesday with potential for 5-10 cm of snow for Winnipeg. But GFS and GLB now show a split type storm system with less snow over Winnipeg. As you can see, still a lot of uncertainty with that storm system with poor model agreement so far, but certainly something to monitor over the next few days.Delete
Whats it looking like now?ReplyDelete
I see the WN has now scaled back the forecast for Monday from 5 cm to 1 cm. Sounds like another miss for the Peg.
Yes, latest guidance trending lower with snowfall amounts for Monday -Tuesday system as they start to agree with taking main storm system across Minnesota and Wisconsin with weaker trough back into Manitoba. Still expecting some minor snow here.. but not a lot at this point. Then it looks like we'll be getting colder again for Christmas into the end of December as massive storm storm system bombs over Ontario around Christmas Day (both GFS and Euro showing 961 mb low over central Ontario!), dragging colder Arctic air into Prairies.ReplyDelete
Rob, just looking at the latest WU forecast & they are now showing measurable snow from Mon night-Wed, is that the GFS/GLB latest model run or still a lot of uncertainty with guidance on this storm before arctic air arrives?Delete
Yes, WU would be using the GFS for their long range forecasts. I think they're trying to show periods of snow developing with that hangback through while the main storm bombs out over Ontario by Christmas Eve. The models seem to be having a tough time resolving the transfer of energy from the midwest system to the Ontario bomb, which would explain the flip flopping and uncertainty with the snowfall forecasts for next week. But at this time, it looks like we should be seeing some snow Monday night into Christmas Eve, perhaps 5 cm over the period, before winds and colder temps arrive by Christmas day as the Ontario bomb takes over. But again.. lots of uncertainty still based on how these systems track and when that Ontario system bombs out.Delete