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| 12Z NAM model valid Monday afternoon shows rain over SE MB and snow west |
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| 12Z GDPS model valid Monday evening shows intensifying storm over Lake of the Woods |
Friday, March 03, 2017
Milder weekend ahead.. winter storm system looms for Monday
After a cold start to March, things will be turning milder this weekend as a southerly flow flushes out the Arctic airmass currently over the eastern Prairies. In Winnipeg, temperatures are expected to climb to the freezing mark on Saturday and +2C on Sunday. Note however that Saturday will see gusty south winds gusting 60-70 km/h, so that high of 0C will feel a lot colder. Sunday looks a lot more pleasant with lighter winds and temperatures above freezing.
Attention then turns to a potential winter storm system that will be impacting southern Manitoba Monday into Tuesday. At this time, models are indicating the development of a storm system over the western United States Sunday that will track across the Dakotas Monday and intensify as it moves into NW Ontario by Monday night. This system will likely start off with some rain or freezing rain over the RRV and SE Manitoba with snow over western MB and he Interlake regions. As the storm pushes towards the Ontario border later Monday, strong northwest winds on the backside of the system will draw in colder air and spread snow and blowing snow across the remainder of southern Manitoba Monday afternoon into Monday night. Travel conditions could become hazardous across southern MB through the day Monday into Monday night, especially with falling temperatures and increasing winds that will freeze up any standing water from leftover rain or melted snow.
There's still a lot of uncertainty on the track of this system and the timing when precipitation will change over to snow which will impact overall snow totals. A track across southeast MB would push the heaviest snow over western Manitoba through the Interlake regions (possibly 15-25 cm) with lesser amounts (5-10 cm) over the RRV and SE MB. A track through Lake of the Woods or east would bring heavier snow over the southern Interlake and RRV. We'll continue to monitor trends over the next few days to get a better idea of how this storm will track, and what impacts it will have for southern MB. In the meantime, be prepared for a potential return of wintery conditions Monday into Tuesday. Stay tuned..
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Models all agreeing that a very deep storm system (around 975 mb) will be tracking across the RRV (pretty much right over Winnipeg by 6 pm Monday) and then up towards Berens River then up along the NW Ontario/Manitoba border by Tuesday morning where it will drop to a very deep 970 mb storm.. very intense for this part of the world.
ReplyDeleteSo what does that mean for us? Well, Winnipeg will dodge the heaviest snowfall with this storm as the bulk of snow will be falling over western MB (Dauphin-Swan River-The Pas), Interlake and much of northern MB where 20-40 cm of snow is possible by Tuesday evening. Here in the RRV including Winnipeg, we'll be on the warm side of the storm initially Monday with above freezing temps and periods of rain spreading in by morning. In fact, some places could even see a rumble of thunder or two as we have some elevated instability move in with this intense low. Rainfall amounts will be generally 5-10 mm but some places could see 10-20 mm if they see heavier bands of showers.
Things get interesting for us by Monday evening as the center of the storm moves to our north, dragging a sharp cold front across Winnipeg/RRV. Rain will change to snow as our temperatures drop from +2C to -5C in a couple hours, and strong NW winds start gusting to 80 km/h causing poor visibility in snow and blowing snow. Any standing water from the day's melt will quickly freeze up Monday evening, making for hazardous travel conditions. Monday night will not be a good night on the highways in the RRV. That snow should push off by Tuesday morning with perhaps 5-10 cm of new snow for us. Tuesday morning commute will be challenging, especially on rural roads, exposed highways and sideroads.
Behind this storm system, we'll be back into the cold weather for awhile.. with below normal temperatures well into mid March. Winter's back, baby..
Most of the Canadian guidance from 12Z and 18Z (with the track right over Winnipeg) gives us 10 mm rain and only 2-3 cm of snow. American NAM and GFS give about 5-10 cm locally with deformation band behind the low. Temperatures drop precipitously after 8-9 PM at which time change over will occur. Before that - warm, moist advection with 50 kt LLJ and 10 C dewpoints coming up from N Dakota will result in an area of rain and embedded convection possibly as noted between 12-6 PM.
DeleteAs for temperatures after the storm.. they will be heavily modulated by negative snow cover anomalies which will extend to at least the int'l border by tomorrow. Looks like a variable period with longwave pattern favorable for cold air over western prairies, but a warm air source to our south. Note that the southern extent of below normal projected temperatures from CDC roughly corresponds to the edge of the continuous snowpack.
EC forecast gives approx. 10 cm snow for Winnipeg overnite and tomorrow. This is a bit above all the raw high resolution guidance which produces 5-6 mm additional moisture after after change over near midnite. Only GFS at this point shows higher amounts. All contingent on strength of deformation band behind the low. System will be intensifying, but moving well off to the NE with the axis of deformation extending out.. hopefully QPF is overdone for tomorrow.
DeleteCanadian and GFS temperature guidance looks too cold - suggesting -30's C by Friday morning. With all the latent heat release from refreezing of water and remaining snowpack, would expect more modification.. especially if we receive <= 5 cm new snow.
A couple of disturbances will track across the US along the main thermal boundary setting up across the Central Plains the next week. Some hints of a moderating pattern starting on March 15/16.
Yeah ain't that something. Now that we are in March winter settles in nicely. Surprise surprise. Honestly how many can say they didn'the see this coming. I for one saw this coming even back in December. We've had back to back early Springs, we certainly won't get a 3rd straight. No way not around here.
ReplyDeleteWow we didn't even get a single cm of snow here. I wish we got the 50+cm they got up in the pas. Instead we just get a bunch of rain and wind.
ReplyDeleteWinter 2016/17 overall was the 15th warmest on record too. Hoping we will see some more extended below normal temps.
Matthew.. Sure, a massive snowstorm would be fun to experience, but then look at the problems it would cause. Travel issues, school and business closures, then a delayed spring and an elevated risk of flooding with all that extra snowpack. I love a good snowstorm as much as the next guy, but now would not be a good time for one. It was a good thing that the RRV missed the bulk of precip with this storm. It would have caused a lot of problems we don't need..
DeleteRob, i'very been hearing of a pattern change to warmer weather starting around Wednesday next week. What are your thoughts on This?
ReplyDeleteYes, looks like a nice warmup to normal or above normal values next week over southern MB with highs near or above freezing by mid to late week. That warming will be tempered somewhat over western MB where they had more snow for the latest storm. Indications are that the milder weather should continue through the end of the month, but another cooler shot possible for the beginning of April. Not a lot of confidence however in the longer term as models have been having trouble with the long range pattern as we transition from winter to spring..
DeleteThe extensive snow pack over SW Manitoba and SE Saskatchewan had a huge impact on overnite temperatures. Areas under the ridge with deep, fresh snowcover dropped to -35 to -37 C (Dauphin and Duck Mts back through Prince Albert, SK). As stated earlier, temperatures locally stayed warmer.. -23/24 C around Winnipeg due to sparse, degraded snowpack. In fact, there is basically only 3-4 cm of frozen slush interspersed with some areas of frozen ground water in open country. Ice has a much higher thermal diffusivity than snow, so we cannot radiate out nearly as efficiently as areas out west.
DeleteNAM really out-shone all other models in terms of performance (projected -23 C at Winnipeg); and had a much more realistic pattern of overnite temperatures which reflected current distribution of snow cover. Was surprised at how bad Canadian guidance was for last night (especially the regional model). There seems to be a real issue with its land surface scheme or inputting of snow cover data (rather than radiative parameterization or physics). It had coldest temperatures over RRV and Winnipeg.. pretty awful.
Temperatures should recover to above normal rapidly by end of next week due to the total lack of snowcover up the the international border. That should finally finish off the generalized snow locally, and open the door for spring to begin. Tributaries and the main stem of the Red River will start to respond.. hopefully early enough to avoid the crest from the Assiniboine River.
Rob, it seems as though long range models are hinting at a major storm system for early next week for Southern Manitoba.
ReplyDeleteWhat are your thoughts on this?
That's weird as WN and Accuweather show no forecast of a major storm.
ReplyDeleteAs our snow disappears locally, temperature anomalies so far this month have been heavily modulated by below average snowcover in N. Dakota and parts of the RRV in Manitoba. Here's a good link to show that from the N. Dakota mesonet:
ReplyDeleteNDAWN Temperature Anomalies
Canadian guidance again looks too cold, seems to still not have a handle on current surface conditions. RDPS and GDPS show overnight lows of -15/-16 C. Currently have strong cold advection ongoing.. with temperatures falling rapidly at Dauphin and Brandon, but these are areas with deep snowcover still present. Would blend with NAM and GFS guidance which show approximately -10 C.. they have had a much better track record of late with overnight lows during the past few arctic incursions. Surprised to see that in fact EC has gone below even Canadian guidance and meteocode with -18 C given the lack of snowcover. We'll see.
Only reached about -12C here last night in Winnipeg. The degraded and sparse snowpack is keeping things warmer. After this brief cooldown it looks like the gateway to warm air from the south opens late this week. Official Snow depth is down to only a couple of cm and most places are almost completely bare now. And it looks like the warmth will persist. Maybe it will be spring for good now. Last year we had a very chilly start to April but that doesn't look like the case this year.
ReplyDeleteI just wish winter had gotten off to an earlier start so that we would have had the snowpack longer. It looks like we will see an early spring for the third year in a row.
There have been bare patches since mid February here in Winnipeg. I am surprised at how inconsistent the second half of winter was after a strong start in December and early January. If we didn't lose that snowpack with the warm ups in the winter I suspect it would have been a much later spring.
ReplyDelete