Thursday, March 01, 2018

Potent storm system to bring widespread snow to southern MB Sunday night into Tuesday

Surface weather map valid midnight Sunday night shows
system bringing widespread snow across southern MB
A potent storm system is forecast to develop over the central US plains later this weekend, and is expected to bring widespread snow to southern MB Sunday night into Tuesday. After a quiet winter that has seen very little snowfall (the lowest Dec-Feb snowfall in at least 30 years in Winnipeg), this upcoming storm system has the potential to produce the most significant snowfall of the season for much of southern MB, including Winnipeg. There's still a lot of uncertainty with how this storm will track and develop, but at this point, it's looking like a widespread snowfall of 15-30 cm is possible for many areas by Tuesday.

Preceding this main storm will be an initial system on Saturday that will bring a band of snow which will push across southern MB and settle into the Interlake region. This initial impulse may bring a couple cm of slushy snow to southern MB, but it shouldn't have much impact with temperatures around the melting point. Some rain may even mix in Saturday afternoon.

Things will start to get interesting by Sunday afternoon as the main storm system starts intensifying as it moves out of Colorado. This storm will track into Minnesota by Sunday night spreading a widespread area of snow across southern MB. The snow may be wet and slushy at first with temperatures hovering around the freezing mark Sunday through Sunday night. Snow could be heavy at times Sunday night into Monday as the storm system slowly pushes across Minnesota, with gusty northeast winds as well. This will make for treacherous driving conditions across southern MB Monday. Snowfall will linger into Tuesday before the system gradually winds down. As noted, snowfall amounts are still tough to predict this far out based on uncertainty in storm track and temperature profile, but in general, it looks like most of southern MB could be looking at 15-30 cm between Saturday and Tuesday night. The highest amounts would likely be over the western Red River valley with some upslope enhancement along the Pembina escarpment, but many areas have the potential to see significant snowfall with embedded bands of heavier snow. Stay tuned as more information becomes available on this developing storm system.     

42 comments:

  1. Latest guidance today is trending west with the heaviest snow with this complex system, with the highest totals generally over western MB and along the western RRV through eastern slopes of the Riding Mtns (due to upslope enhancement) where 20-30 cm are possible by Tuesday. That doesn't mean we miss out here in Winnipeg.. I still see us getting snow Monday, but amounts may be more in the 10-15 cm range instead of 20 or more. Snowfall will likely be less towards the Ontario border (perhaps 5-10 cm) As usual, models will have difficulty pinpointing finer details with a big system like this, so it's important to keep up with updates as new info become available. Don't just go by a forecast that you heard 3 days ago.. things will change as newer information is processed into the models.

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  2. If be very happy if it keeps trending that way. Love a good snow storm, but on the weekend!

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  3. Thanks Rob,

    I'm sure it will be a dud and all the good snow will be to the west.

    Thanks for the constant updates.

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  4. Even if most of the snow ends up west, it'll all eventually end up in the Assiniboine anyway.

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  5. The rivers in MB can use it but a lot will just melt into the very dry soil. It amounts to little more or less than an 30 mms or an inch of pcpn.

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  6. Euro only showing 7 cm for Winnipeg this morning come on! But Gem, geps, nam and gfs all show at least 20 cm. So is the euro wrong here? I find they tend to under forecast precipitation here anyone else agree?

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    1. I still wouldn’t favour one model yet. Euro was showing more for Winnipeg yesterday. Models still trying to get a handle on this thing. But it does look more likely that western MB will see the most from this system. I’ll post an update later this morning after the morning guidance is in.

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  7. So sick of the SW corner (and often the SE corner too) always getting the bigger storms while everything skips over us here in the middle.

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  8. Any chance the storm shifts east and we get larger amounts?

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    1. Not looking likely. Although this storm is a Colorado low type storm system, it will not be tracking into NW Ontario like classic Colorado lows usually do. This one will move into southwest Minnesota (or southeast SD), then stall and loop before heading east towards the Ohio Valley. This will tend to keep the snow from advancing too far east across southern MB. There will be an extension of this storm extending into western MB (known as an "inverted trough") which will focus the heaviest snow over eastern SK and western MB. Even so, there will likely be overrunning precipitation over the RRV and SE MB, although it may start off as ice pellets Sunday evening before changing to snow Sunday night. That would tend to hold down snowfall amounts here initially. Snow should gradually spread over Winnipeg/RRV Sunday night through Monday with general amounts of 10-15 cm possible by Tuesday morning.. but 15-30 cm likely over western MB. That's how it's looking like right now based on the latest guidance. I'll update things today and tomorrow as more info becomes available.

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  9. New Euro is in, and they're giving about 10 cm to Winnipeg by Tuesday, 15-20 cm over southern and western RRV, and 20-30 cm over western MB towards the SK border. Barely anything east of Winnipeg to the ON border. Other models give more to Winnipeg.. in the 10-20 cm range. I'm thinking 10-15 cm still looks good for the city.. 5-10 cm east of Winnipeg, 15-25 cm west of the city. Bulk of snow falling Sun night into Monday night, possibly beginning as ice pellets or wet snow Sunday afternoon/evening.

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  10. Rob, is freezing rain a possibility for Winnipeg as well tomorrow night before the changeover to snow?

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    1. Yes, there's a risk of freezing rain or ice pellets (sleet) Sunday evening as the main precipitation shield moves in. But it's looking like it will be more of an ice pellet risk than freezing rain based on the temperature profiles, which isn't as bad. Regardless, it shouldn't last too long as the airmass cools and precip changes to snow Sun night.

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  11. EC forecast discussion says they will likely be issuing winter storm watches for southern MB with the afternoon forecast update (by 330 pm) Heaviest snowfall expected over Westman with 20-30 cm possible along with blowing snow. Less snow (7-15 cm) but mixed with freezing precip for RRV/SE MB.

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  12. Sunday morning update: Well, things are coming better in line with upcoming storm system based on overnight model runs. Here's the latest:

    Storm system will be pushing up into Dakotas later today with precip shield expanding over southern MB this afternoon. Precip will move into the RRV by late afternoon/suppertime reaching Winnipeg by 6-7 pm. Precipitation type will be an issue initially as model soundings and precip type charts show precip starting as ice pellets or rain/frzg rain over much of the RRV/SE MB due to an elevated nose of above freezing temps this evening. That however will quickly erode as precipitation intensifies, so look for a quick transition to snow this evening. Snow should continue through the night, heavy at times into Monday morning before tapering off Monday night. General snowfall amounts for Winnipeg/RRV should be in the 10-20 cm range, with lesser amounts to the east and higher amounts to the west. I think Winnipeg should see a good 10 cm by 8 am Monday morning with another 5 cm during the day Monday.. so storm totals here should be around 15 cm by Monday night.. possibly up to 20 cm if we get into some heavier snowbands. Overall for Winnipeg, low end totals will be around 10 cm, high end 20 cm.

    Highest snowfall totals with this storm system will be over western MB especially around the Riding Mountains which will benefit from colder temps, higher terrain, and upslope enhancement. These areas could see 30-40 cm of snow by Tuesday morning.

    That's how it's looking right now in model land. Soon, we'll be able to use radar to see what's actually happening, and get better specifics for timing/precip type/amounts/ etc. Will be interesting to see how this unfolds!

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    1. Morning guidance coming in with higher snowfall totals for Winnipeg and RRV tonight and Monday. Some showing 20-30 cm by Monday night. Not ready to buy into that yet, but it's looking less likely that this thing will be a bust for Winnipeg/RRV. Bring it on!

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  13. Looks like weather networked dropped the snowfall amount. Any validity?

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    1. That's odd.. model guidance has been creeping up if anything and almost all in agreement that we'll see 15-20 mm of melted precip over next 24-36 hours. Even the conservative Euro is giving us 15-20 mm of precip (a good 15 cm of snow) Not sure why TWN would drop amounts at this point. Certainly not supported by the latest guidance.

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    2. Expecting more to fall as rain?

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    3. No, only showing about 1 mm of rain this evening then 5 cm of snow tonight through Monday.

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    4. That would make me happy! I'm thinking 10 cm for my place and 15 - 20 cm in the City from east to west.

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  14. I live a little ways northeast of the city, and models are showing the snowfall amounts drastically cutting off as one heads east. It would be a shame to see Winnipeg get a good dump while I miss out, lol

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  15. Late evening update: Precip has changed to snow in Winnipeg and will continue through much of the night before band dissipates or weakens overnight. Accumulations in Winnipeg have been minimal so far as of 10 pm.. only about 1 cm or so whereas models had us already up to 5 or 6 cm by now, so they didn't account for the ice pellets and melting this evening. So we need to get some decent snowfall rates over the next few hours to get towards 10 cm by morning. If we don't.. then we'll end up with 5 cm or so instead tonight. For Monday, models are showing only light snow over Winnipeg and east.. possibly another 2 to 5 cm with some waves of snow pushing up from the southeast. Overall, it's looking like maybe 10-15 cm for Winnipeg, and likely on the low end of that if we don't get into some decent rates tonight.

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  16. I measured 14 cm of heavy wet snow as of 7 am at my place. Generally 12-18 cm being reported across the city as of 8 am. Could see another 2-5 cm today so we’ll be close to 20 cm with this storm. A winter wonderland out there!

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  17. Looks like easily 5 more cm today. Coming down hard!!

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  18. Hi Rob,

    When do you think this will stop today?
    Done by supper time?

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  19. Saw your twitter post. Thanks for the update.

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    1. Yeah, I tend to be more active on Twitter with updates than here. I just find Twitter quicker and easier.. and also I like posting graphics with my responses to help explain things. Can't do that here..

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  20. Picked up another 7 cm of snow today at my place between 7 am and 2 pm. 21 cm storm total. Seeing reports of 19-23 cm generally across the city. All of it falling within 18 hours! We had more snow from this storm than Jan and Feb combined (17.6 cm). We also basically doubled our winter precip in this one storm. YWG airport recorded 14.4 mm of melted precip with this storm.. and they had 14.6 mm total precipitation in the entire 3 month period of Dec-Feb. 19 mm at the Forks. A good soil moisture input leading into spring.

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  21. Rob,

    Speaking of Spring, are there any sings of spring in the near future in terms of a warmup or are we expected to remain generally below seasonal over the next little while?

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    1. We’ll stay near or slightly below normal this week (normal high is now -3C) but there are hints of a warmup by mid March. Too early to say if it will be a temporary thing, or a transition to a springlike pattern. The good news is I’m not seeing signs of a prolonged well below normal temperature pattern in the next week or two.

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  22. Weak impulse moving across southern MB Saturday will bring an area of light snow across western MB overnight spreading into the RRV Saturday morning. Doesn't look like a lot.. perhaps 2-3 cm of snow for Winnipeg mainly between 10 am and 6 pm. More of a nuisance snow than anything.

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  23. Hey Rob,

    I know its a week away but do you see a potential snow storm next week? Weather network has been flirting with this potential storm for the last few days now.

    Thanks.

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  24. Chance of some minor snow this weekend otherwise models are pretty quiet for us next week. Most of the storm action looks like it stays to our south in the US

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  25. Hi rob
    Any insight on the snowfall in Sunday’s forecast ? Will Winnipeg get anything?

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    1. Looks like an area of snow coming through Sunday morning into the afternoon.. could give Winnipeg/RRV a quick 2-5 cm by mid afternoon. But winds will be gusty from the south, and temps will be near or above zero, so actual snowfall amounts will be minimal. Even so, we could see an hour or two when the snow comes down pretty good and gives low visibility.

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    2. Well, that snow was a complete bust for Winnipeg. Had a bit early this morning as an area of snow moved to our northwest, then a secondary area of snow went to our southeast towards Sprague/Whiteshell. Bottom line.. Winnipeg missed both areas of snow, not that I'm disappointed. But admittedly, wasn't forecast well..

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    3. Or Peg Stormshield is working instead of tweeting

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  26. First thought that comes to mind with the outlook for the next week...WTF?!

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    1. Yeah.. not a good start to April. Really getting tired of this below normal nonsense. Need to get rid of this snow and move into spring!

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  27. Were we below normal again? If we were how many months in a row?

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    1. Didn't seem like it, but March in Winnipeg was pretty close to normal, with an average temperature of -6.1C vs the 30 year average of -5.8C. So just slightly below normal, but not by much. Feb was about 3C below normal while January was 1.5C above normal.

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