Tag: Warmer Weather

Warmer Weekend Ahead With An Uncertain Finish

Brad Leave a comment

Warmer weather will wash across the Red River Valley this weekend as a south-westerly flow brings in mild Pacific air. While the sun won’t be overly present, conditions will be quite pleasant with mild temperatures and light winds. The weekend will finish on an uncertain note as a Colorado Low ejects from the Central Plains with wavering agreement on where it’s heading after that.

500mb Winds for Sunday Morning

500mb winds valid for Sunday morning at 12Z. A complicated set-up will be underway as the polar jet merges with the sub-tropical jet and a shortwave from the northern Prairies merges into a developing Colorado Low.
Friday

Mostly cloudy.
-6°C / -9°C

Skies will be mainly cloudy today as a warm front pushes eastwards towards the Red River Valley. Temperatures will climb up to –7 or –6°C, a welcome break from the cold temperatures we’ve had over the past week. Winds will pick up out of the south-southeast to 30–40km/h this morning with a slight chance of some local blowing snow through the Red River Valley. There will be a very slight chance of a few flakes of snow but there won’t be anything that can be considered significant. Temperatures will drop a few degrees tonight to about –9°C under mainly cloudy skies.

Saturday

Saturday

A mix of sun & cloud.
-4°C / -9°C

Perhaps the nicest day of the weekend will be Saturday as the clouds begin to break up a little and temperatures climb as high as –4 or –3°C. Winds will remain fairly light through the Red River Valley through the day. Not much to say for Saturday night; skies will likely clear in the evening but fairly quickly cloud over again early in the morning on Sunday.

Sunday

Sunday is a very complicated weather day. As it stands right now, we may see absolutely no snow or…quite a bit of snow, including the potential for a blizzard through portions of the Red River Valley. Temperatures should remain close to what they look to be right now with highs near –5°C across much of the Red River Valley. Winds will likely remain relatively light, regardless of the overall pattern, as there will be no significant Arctic high building into the region.

As for the complicating factors…

Sunday

Mostly cloudy. Snow/freezing rain uncertain.
-5°C / -11°C

The general synoptic pattern will be as such: a significant Colorado Low will be ejecting into central Nebraska on Saturday night with a sharp trough digging northeastwards into SE South Dakota while, at the same time, a relatively weak low pressure system slides south-eastwards out of northern Saskatchewan towards central Manitoba. By Sunday morning, the Canadian low and it’s associated jet stream will merge with the Colorado Low with the CO low situated in central Nebraska with a sharp trough extending northwards through extreme western Minnesota then arcing through the Red River Valley northwestwards towards The Pas, MB. It’s always a concerning issue when the troughs end up west of the Red River Valley, as it can often mean a northward progression of the weather into our area.

Models have notorious struggles with complicated setups where two distinct atmospheric streams merge. It’s an incredibly dynamic, sensitive process in which even small changes can dramatically effect the evolution of the entire system, so models can often waver wildly on what the outcome will be from small changes in their initial conditions. That being said, using ensemble forecasts, the track of the low, and it’s associated snow, has been creeping northwestwards; two days ago the entirety of the snow was forecast to push only into Central Minnesota; now it’s forecast to clip southeastern Manitoba, including Sprague and portions of the Whiteshell. Model trends can sometimes be more helpful than the actual model output, and combining the ensemble’s northwards trend with the knowledge that this is definitely a situation where the model may not tilt the 500mb trough enough and then, as a result, not bring the low far enough north or west, I can’t say with any certainty what Sunday will bring.

There’s a distinct chance that the snow will remain entirely on the US side of the border and we’ll be relatively unaffected by this system. Should things develop in such a way that the low digs a little more and the trough tilts a little more, it’s also entirely possible that another 5–15cm of snow, or potentially higher, will fall across the Red River Valley. In addition to the uncertainty with all these elements, should the precipitation push further to the NW into Southern Manitoba, there will be a distinct potential for freezing rain as 850mb wet bulb temperatures sit on the positive side of the 0°C mark.

The reality is that for this type of setup, it’s simply too early to tell what’s going to happen. We’ll most certainly be providing updates in the comments below on the development of this Colorado Low. For now, it’s safe to assume that Sunday will be a warmer day with winds in the 20–30km/h range, but the actual weather conditions may end up being quite poor depending on the evolution of this system.

Another Clipper System Brings Snow to Southern Manitoba

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Another Alberta Clipper system is racing eastwards across the Prairies and will bring another shot of snow to Southern Manitoba today.

Snowfall Accumulations for February 6, 2013

Snowfall accumulations through the day today. A swath of 5–10cm of snow will cut across Southern Manitoba as an Alberta Clipper dives into North Dakota.
Wednesday

Snow. Total 2-4cm.
-13°C / -20°C

Riding along the strong northwesterly jet stream that’s been in place over our region over the past few days, another clipper system will race across Southern Manitoba today. This system will prove to be slightly more challenging than Monday’s clipper system as it looks to be more compact and intense. When these two aspects combine, it always proves to be a tricky forecast; small changes in the track of the system (for example, even a shift of 25–30km north or south) can result in dramatically different weather for places along the edges of the track.

The low will slice across northern portions of North Dakota before diving into central Minnesota this evening. The heaviest snow should run just north of this low track with 5–10cm on the ground by the evening. Accumulations will drop off quite quickly to the north of this band which is, of course, where Winnipeg will sit. As seems to be near-climatological wizardry, Winnipeg will yet again sit right on the edge of heavier snow, making the forecast quite sensitive.

The most probable outcome today will look something like this: snow will push into Winnipeg early this morning and intensify fairly quickly. The heaviest snow will mid-to-late morning, and we’ll pick up a fairly quick 2–4cm of snow. It will start to taper off quite quickly after noon, with some lingering light snow lasting through into the evening. Like Monday’s system, there is a chance that the light snow could add another cm or so to the totals for the system. If this system tracks a little further north (even 20–30km), it’s entirely possible that we’ll see another 5–8cm of snow here in Winnipeg. We’ll provide some updates as soon as we can more definitively say which outcome is going to happen.

To the south of Winnipeg, snow will last through more and more of the afternoon the further south you go with accumulations increasing. For communities close to the international border such as Altona, Gretna and Morden, as much as 8–10cm of snow may be on the ground by the end of the day. Winds should remain light enough that blowing snow should not be an issue through the valley today. Things will clear out this evening with some lingering cloud left behind as we head to a low near –20°C.

Thursday


Mix of sun & cloud.
-16°C / -19°C

Thursday will bring a mix of sun and cloud and a high just a few degrees cooler than the day before. Instead of plunging back into the deep freeze like we normally do after many clipper systems, this one is embedded within a larger warming pattern; the highly meridional flow[1] we’ve had lately is slowly being modified and forced into a more zonal flow[2] by a developing complex of low pressure systems over Alaska. Temperatures will climb to around –16°C today and drop only a few degrees tonight as a southwesterly flow aloft kicks in and starts pushing warmer air over our region.

Friday


Mix of sun and cloud.
-6°C / -13°C

We’ll transition into the milder air that we’ve been advertising would be on it’s way by Friday. A solid southwesterly flow aloft will help push temperatures up to around –5 or –6°C across the Red River Valley under a mix of sun and clouds. This warmer weather will continue through the weekend, with highs generally between –5°C and –8°C with overnight lows dropping just below –10°C.

  1. A meridional flow is one that has a larger north-south component than east-west in the flow directions. In Winnipeg, meridional flows often bring in bitterly cold air in the winter (from the north) and oppressively hot weather in the summer (from the Gulf of Mexico).  ↩
  2. A zonal flow is one that whose east-west component is greater than it’s north-south. Zonal flows tend to moderate temperatures across the Prairies as mild Pacific air washes out the colder Arctic air.  ↩

Warmer, but not Warm

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Warmer weather will be more common in Southern Manitoba this week, but that’s not to say it will be warm weather. Rather, it will just feel warm relative to the arctic weather we’ve experienced lately.

Alberta Clipper snowfall map on Monday

The Alberta Clipper that will bring snow to Southern Manitoba on Monday

The weather this week will be characterized by a semi-zonal flow aloft. A zonal flow is when the jet stream moves west to east, which tends to give us neither really cold weather nor really warm weather. A series of small disturbances will ride along the jet stream, bringing us a couple chances for snow through the early part of the week.

Monday

Monday
image
Light Snow
-12°C / -17°C

An Alberta Clipper system will roll through Southern Manitoba on Monday bringing more snow along with it. This will be a fairly weak clipper, without much moisture to work with. At this point it looks like the “heaviest” band of snow will pass somewhat south and west of Winnipeg, where up to about 5cm could fall. In Winnipeg and area amounts will in the 2-4cm range. There won’t be much in the way of wind with this system, so its affects will be limited to adding more slippery sections to roadways.

Tuesday

Tuesday
image
Mainly Cloudy
-10°C / -15°C

Tuesday will be a fairly nice day overall, with light winds and mainly cloudy skies. Temperatures will be fairly close to seasonal values, with highs in the upper single digits or lower double digits (below zero of course).

Wednesday

Wednesday
image
Snow
-7°C / -18°C

It appears that we’ll see yet another Alberta Clipper on Wednesday. It will bring snow once again, with accumulations probably being a bit higher than those seen on Monday. It’s hard to say exactly how much we might get from this clipper, but an early guess would be anywhere from 4 to 8cm in Southern Manitoba. Check the comments for an updated forecast for Wednesday over the next couple days.

For once there may be something of interest to talk about in the long-range. There have been numerous indications over the past week that we may be heading toward a more prolonged warm period that could exist through mid-February. The Climate Prediction Centre, NAEFS ensemble, ECMWF, and arctic oscillation predictions are all in line with milder weather for the early to mid-month period. They don’t give a clear indication of how mild it could get, but certainly arctic outbreaks like those experienced in January could be much harder to come over the next while.

A Break From The Cold

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A break from the bitter cold snap that we’ve been under the influence of over the past week is on it’s way this weekend.

850mb Temperatures valid Saturday Morning

850mb temperatures on Saturday morning from the GEMGLB model. Near–0°C or above temperatures are forecast to push across Southern Manitoba aloft, bringing much warmer weather to the region.

Behind yesterday’s Alberta clipper system, a zonal flow[1] is pushing into the Prairies and breaking down the entrenched northwesterly flow that has been in place over the past week bringing us multiple nights with overnight lows in the mid-minus 30’s and many daytime highs barely climbing over –25°C. The milder Pacific air contained in the more zonal flow will begin to work it’s way eastwards across Alberta and Saskatchewan today, bringing daytime highs closer to –7 or –8°C instead of –20°C.

Friday

Friday

Sunny
-20°C / -29°C

For us in Winnipeg & across the Red River Valley, we’ll face one more day with quite chilly temperatures. Under mainly sunny skies, temperatures will climb to about –20°C with light winds. Temperatures will drop quite a bit tonight as another arctic ridge passes over us; our last cold night before the warmer air pushes in will see us with temperatures bottoming out near –29°C.

Saturday & Sunday

Saturday

Mix of sun and cloud. Increasing cloudiness overnight.
-12°C / -13°C

We’ll see a mix of sun and cloud on Saturday as the milder Pacific air finally pushes in. Temperatures will climb quite quickly through the late morning and early afternoon from our overnight low all the way up to –12°C by the evening hours. By the evening there may be a few light flurries over the southeast portion of the Province (Whiteshell & Sprague), but through the Red River Valley there’s no significant chance of any snow. Temperatures will remain fairly steady overnight as more clouds push in.

Sunday

Mainly cloudy. Chance of flurries overnight.
-7°C / -8°C

We’ll see mainly cloudy skies on Sunday as more moisture and lift begin to spread over the province ahead of an approaching shortwave. Temperatures will climb to around –7 or –6°C across Southern Manitoba; the warmest day we’ve had in what seems like quite a long time. Overnight, an increasing chance for light snow will move into the province, starting with southwest Manitoba in the evening hours and slowly spreading eastwards overnight. Temperatures will remain steady, perhaps drop a degree or two, overnight as we remain cloudy with warm air over the region.

Next Week

Next week is looking like we’ll see a return to colder weather. There’s some uncertainty with regards to the strength of Monday’s system; it may be a fairly organized feature that brings close to 10cm over SW portions of the province and 5–10cm over the Red River Valley and areas eastwards, or it may end up being a rather disorganized system that brings just some scattered light flurry activity with only a couple cm for most places. With either scenario, it still looks like Monday will be the warmest day yet in our little break from the cold. Unfortunately, it looks that once this system passes, Arctic air will once again push back over the Eastern Prairies and establish itself; locking us back into a sunny, but very cold, weather pattern with daytime highs back near –20°C.

  1. A zonal flow, with respect to meteorology, is one that travels more west-east than it does north-south. By contrast, a meridional flow is one that has a larger north-south component than west-east.  ↩