Tag: Snow

Slight Cool Down Before Mild Temperatures Return

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26 temperature records were broken across the Southern Prairies yesterday as warm Pacific air flooded the region tied to a low pressure system tracking through central SK/MB. The RRV will see a cooler weekend as colder air is creeping southwards on the backside of this system, however the deep freeze is still a little ways off.

Overnight Snow along a weak trough in NW flow

3hr. QPF from the 12Z Jan 06 GEM-REG valid at 09Z Saturday Jan. 7

An area of snow will slowly push southwards through the RRV today, brining only minor accumulations to the region. The system should clear out by this evening, with the chance of a few light flurries through the night in a weak northwest flow. A ridge of high pressure will then work across Southern Manitoba Saturday & Sunday, brining cooler temperatures to the area with daytime highs in the -10 to -5°C range and overnight lows in the -10 to -15°C range through the region.

By Monday, another low pressure system tracking through the northern Prairies will drag more Pacific air over the Prairies once again pushing temperatures above 0°C. Many areas in Southern Manitoba should see daytime highs Monday near 5°C. Currently, it doesn’t look like temperatures will reach nearly as high as some places did yesterday, but things will become a little clearer closer to the day (naturally). It’s quite likely we’ll more daytime high record temperatures broken on Monday.

850MB temperatures from the GEM-GLB

850mb temperature from the 00Z Jan 6 GEM-GLB valid at 00Z Thurs. Jan 12

After that, it looks like we’ll be seeing a bit of a cold snap. On the back side of the system, a fairly strong push of Arctic air will flood through the Prairies, bringing us our coldest temperatures in a while. It looks reasonable, as temperatures in Oymyakon, RU have dropped below -50°C (-55°C when I checked last night), with daytime highs only around -35°C, which is a good indicator for colder weather pushing over the poles towards the Prairies. We won’t get nearly as cold as they are, but by the middle of next week, daytime highs around -15°C with overnight lows around -25°C are certainly possible, as 850mb temperatures are forecast to dip down to -25 to -30°C over Souther Manitoba . This system looks relatively dry, however we may shift into a pattern that will favour clippers tracking along the international border which may bring long-awaited snow to southern portions of the Prairies and the Northern Plains.

Chance of Freezing Rain Over The Red River Valley

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A large upper trough swinging across the Prairies is supporting two low pressure systems, one in central Saskatchewan and one in the Northern Plains of the United States, that will move across Manitoba overnight and tomorrow morning, bringing with them snow and the risk of freezing rain.

Dec. 31 Prog

For southern Manitoba, the main concern will be the precipitation generated along the apex of the frontal wave as it occludes southeastwards from the northern low in Central Manitoba to Minnesota. The warm front will align somewhere near a line from Winnipeg to Sprague, and slowly shift south/southeast through the day. Areas near the International Border have the greatest risk of freezing rain, due to the higher intensity of the precipitation expected there. The risk diminishes as you head north towards Winnipeg. I agree with the latest Environment Canada forecast that calls for ice pellets in Winnipeg; the warmest air should stay south of the city and we will likely have enough cold air entrenched to freeze any rain that comes out of an above-freezing layer. I can’t exclude the chance of a brief period or two of freezing rain, especially late overnight and early tomorrow morning. As this system develops, snow will become the predominant weather type, and much of the RRV can expect between 2-4 cm of the white stuff, while a few localities may get up to a couple inches.

I think it’s likely areas south of Morris will see some duration of freezing rain before sitching over to snow. The good news is that this doesn’t have the makings for a large-scale freezing-rain event, so there shouldn’t be any concern of widespread highway closures. Given that some roads are already very slippery, however, drivers should take caution when travelling overnight or tomorrow as fresh snow may be hiding a layer of ice underneath. Always drive with care when freezing rain and snow occur.

This system should clear out tomorrow afternoon, bringing in strong northwesterly winds behind it gusting up to 70 km/h. Fortunately, the arctic cold front is well to our north, so while chilly, we likely won’t even seen our temperature drop to even -15 to -20°C for overnight lows before the next swell of warm air pushes across the Prairies, bringing us continued pleasant winter weather with daytime highs in the -5 to 0°C range! The strong winds will move in tomorrow evening and last through much of the day on Sunday before tapering off, bringing us wind chill values as low as -25 in Winnipeg.

So hang in there, a couple chilly days and we’ll be back to pleasant temperatures with a fresh coat of snow! Happy New Year!

Rainy Day on Tap for Winnipeg

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Winnipeg will see a few showers this morning develop into a rainy afternoon before it all turns to wet snow this evening as the first “summer-y” system of the year pushes through Southern Manitoba.


Hand-analysis of the 925mb Height/Thermal Field for 12Z March 20

A very summer-y low is passing through North Dakota this morning, with a warm front draped west-to-east across much of the state, just south of the international border, before it dives south through Iowa. This system has brought with it copious amounts of warm air and is the first real summer-like system of the year.

East of the warm front, in Iowa, a complex of thunderstorms are moving across the state, supported by a 60 kt 850mb jet riding over the surface warm front, bringing with it moist air with Θw values near 20°C. This 60 kt LLJ then arcs north and pushes into Northwestern Ontario. As can be seen by the red shading in the analysis I have done this morning, warmer air is being pushed up through much of Southern Manitoba, including the RRV, Interlake and Parkland regions of west-central Manitoba. With the surface warm front just south of the border and plenty of warm air overrunning it, this has brought a mix of precipitation for areas in Southwestern Manitoba across the Trans-Canada highway into the Whiteshell and north.


1.5km CAPPI Radar Reflectivities

Pilot Mound, Morden, Steinbach and Sprague should escape most of the precipitation until later today. Being so close to the warm front, the precipitation is actually developing north of them where the air aloft that is being lifted is saturating. For those areas, expect a cloudy day with drizzle likely and if the wind manages to calm a bit (say to 15 km/h or less) fog patches are certainly possible. By later this afternoon, rain should move into the area, though with accumulations of about 5mm. For Portage la Prairie, Winnipeg, Dugald, Selkirk/Gimli and the Whiteshell, showers seen this morning will continue to develop and intensify to an area of rain by this afternoon. Expect to see about 5-10mm of rain before switching over to wet snow this evening. Do not be surprised to see a few snowflakes today, though; as it is quite likely for there to be embedded convection in the rain bands, areas of heavier precipitation may be able to produce rain mixed with snow as the shallow warm pool is unable to completely melt all the precipitation.


12Z 20 March 2011 GEM-REG 12h QPF Accumulation valid 00Z March 21 2011

Further west, over the higher terrain, the precipitation will predominantly be snow. Dauphin/St. Rose/Minnedosa are under a heavy snowfall warning as 10-15cm of snow are expected by this evening. Fortunately, as this weather system is driven primarily by warm air, the precipitation should end quite quickly as the low pulls out of our area this evening.

All in all, it’s quite a good day to stay inside with a hot drink and read a book. A little bit of everything will be seen through the afternoon, and unless you’re a big fan of having a new “Rally Inspired” paint job on your car, it’s best to stay off the messy, messy roads.

The next significant weather system will pass through on Tuesday, and this system will receive plenty of attention as it develops as it has the potential to produce significant amounts of snow/rain, and could add uncomfortable amounts of water into the Assiniboine/Red River drainage basins. I’ll post some more information about that system on Monday when things are a little clearer.

Snow on the Way

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A significant storm system is currently developing in Montana this morning that will push it’s way eastwards across the Northern Plains of the United States and into Northwestern Ontario by Thursday morning.

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Snow will push into Saskatchewan today and a snow band will develop aligned somewhere between Shaunovan and Kamsack, as shown in the above model image. There is a slight chance that some of these sites will see warning-level amounts of snow, however it currently looks like the possibility of that is borderline. This band of snow will then consolidate and push into Central Manitoba, while a second impulse brings an area of lift into Southeastern Saskatchewan and Southern Manitoba.

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This second band of snow will move eastwards through Southern Manitoba, giving most areas somewhere between 5-10cm of snow. Brisk northerly winds will push into the Red River Valley on the backside of the low as it moves into Northwestern Ontario, and with fresh snow, significant blowing snow will exist in any open areas inside the valley. Based on this projection, the snow would begin in Winnipeg late Thursday morning and last until sometime Friday morning, with the heaviest snow and worst conditions coming by late Thursday afternoon. Significant blowing snow would most likely occur during the evening and overnight period, which will be important to take into account for anybody planning to travel on Thursday evening/night, especially through the southern Red River Valley.

At least, that is how this system should evolve. The jury is still out on what will actually happen. The last 5 runs of the GEM-REG model have all produced drastically different results. The GFS and NAM offer little consensus on where the heaviest snow will be, the UKMET shows similarities to the 00Z GEM-REG run (from which I’ve gotten these images), and ensemble models show little confidence in the track and evolution of this system. Why is this? One look at the Water Vapour imagery shows the problem:

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The two +’s in this image are the two main vorticity centers for this incoming system, and the yellow arrows depict their rough paths given the streams they are each in, respectively. This system is a somewhat unique scenario, wherein the two “streams” of air are close together, and are moving in sync. Typically, the reason this is a problem is because the models can have a hard time dealing with the energy distribution between the two streams. We have seen many times in the past where model solutions flip flop back and forth and back and forth, even when the event is close (less than 36 hours away) where the model error could be attributed to the complex dynamics that occur when this situation occurs.

So if we don’t actually know what’s going to happen, what’s going to happen?  Odds are that the RRV will get snow on Thursday.  I’ll go on record saying we’ll get at least 3-4 cm.  In a worst case scenario, a line from Pilot Mound to Winnipeg could get as much as 10-15 cm, however I think that’s quite unlikely.  If we get fresh snow in the RRV, there will be blowing snow Thursday night as the winds pick up to 50G70 km/h out of the north.  And sadly, our wonderful warm spell is going to come to an end this week, with temperatures plummeting to -20°C by Friday morning.

I’ll keep the comments of this post updated as the system develops and try to narrow down the impact it will have on Southern Manitoba.  Stay tuned!