Mild Weather Continues

This week will remain mild with temperatures generally on the positive side of zero. However, there will be a chance for precipitation on Tuesday.

Today will see a continuation of Sunday’s warm weather. High temperatures will be in the mid single digits in the Red River Valley, and perhaps a bit higher over the snow-free area to our west. Skies over the Red River Valley will be a mixture of sun and cloud, while conditions over western Manitoba are mainly cloudy. The only wrinkle in today’s forecast is the potential for fog tonight, aided by the additional moisture generated by the snow melt.

A low pressure will pass to our south on Tuesday, bringing rain and snow to southern Manitoba. At this point it looks like precipitation over south-eastern Manitoba will primarily come in the from of rain. The Red River Valley will probably see a mix of rain and snow, while western Manitoba sees primarily snow. Large amounts of rain/snow are not expected, but models hint at the potential for localized bands of moderate precipitation which could bump up totals in some areas. Most areas will probably see 3-6 mm of accumulation, in the form of rain and/or snow.

RDPS MSLP & 3hr. QPF valid Tuesday morning.
A weak Colorado Low will bring precipitation to the Red River Valley on Tuesday.

Wednesday will be a slightly cooler day as a colder air mass surges southward behind Tuesday’s departing low pressure system. High temperatures will be near the freezing mark with breezy north winds.

Long Range

The long range forecast shows no indication of winter returning. Models strongly suggest that most, if not all, of March will be seasonably warm. Enjoy the snow now, it may not last much longer!

First Major Snowstorm of the Winter Incoming

Southern Manitoba has its first major snowstorm of Winter 2015/16 on the doorstep as a Colorado Low moves northeastwards through the American Plains and is poised to produce 10–20 cm of fresh snow through the Red River Valley.

The incoming Colorado Low has spread snow across South Dakota this evening which is now pushing into North Dakota and Minnesota. This area of snow will intensify as it heads northwards courtesy a steadily organizing weather feature called an inverted trough. This trough of low pressure extends north/northwest out from the centre of the Colorado Low and will draw moisture into the Red River Valley and produce a swath of heavier snow through the region.

Mayville RADAR @ 10:29PM CST on December 15, 2015
At 10:29PM CST, Mayville RADAR in North Dakota shows a broad area of snow pushing northwards towards Manitoba.

At this point, it looks like the snow will begin pushing across the U.S. border sometime between 2 and 4 A.M. and then spread into Winnipeg before 4 and 6 A.M.. The heavier snow will build into the Red River Valley between 6 and 9 A.M. and persist until near lunch time. Through the first half of the day, as much as 10 cm could fall; that’s a fairly intense snowfall rate and will undoubtedly have significant impacts on transportation. The snow will ease slightly for the afternoon, but still be fairly persistent, dropping another 2–5cm or so.

Winnipeg Forecast Sounding for 11Z December 16, 2015
The forecast soundings for Winnipeg on Wednesday morning show very favourable thermodynamic profiles for moderate to heavy snow.

Heading into the evening and overnight hours, the snow will begin to become a little bit more disorganized save for one area known as the deformation zone. This feature will be the western-most extent of the snowfall and will typically have slightly more organized precipitation along it. Best indications at this point are that the deformation zone will line up through the Interlake and Red River Valley, meaning it’s fairly likely that more persistent light snow will last through the night. This snow could produce anywhere from 1–3cm more.

AWM Snowfall Outlook for December 15-17, 2015
AWM Snowfall Outlook for December 15-17, 2015 with verification overlaid.

By Thursday morning, the snow should be tapering off to flurries and moving out of the region. When all is said and done, it’s likely that anywhere from 10 to 20cm of fresh snow will have fallen in the Red River Valley. Localized amounts could possibly exceed 20cm in a few particular locations, namely anywhere that may see upslope enhancement in the northerly winds: the western escarpment of the Red River Valley and north side of Turtle Mountain being to of the most likely places. These higher amounts would be very localized, though, and are not reflected in the above snowfall forecast, which is looking more at large-scale snowfall totals.

Snowfall Warning Highlights
The highlights of this Colorado Low storm system

Environment Canada has issued a snowfall warning arcing across the Red River Valley with the discussion showing very similar thinking: 10–20cm of snow, heavy first thing Wednesday morning, then blowing snow and cooler temperatures heading into Thursday.

Cooler with Blowing Snow Behind the Colorado Low

Beginning Wednesday evening, northwesterly winds will begin moving into southern Manitoba. Despite the cooler temperatures pushing in and the relatively strong winds aloft, winds will likely only reach around 30 gusting to 50 km/h overnight.[1]

By Thursday morning, the wind will strengthen to 40 gusting 60 km/h, which when combined with the fresh snow, will almost undoubtedly produce fairly widespread blowing snow through the Red River Valley. These stronger northwesterly winds will also be ushering in a much cooler air mass that will drop temperatures to –20°C by Saturday morning.

This colder weather, while an abrupt change from what we’ve been seeing for the past month and a half, is actually not all that uncommon. Normal daytime highs for Winnipeg this time of year are around –10°C with normal overnight lows near –20°C. So while we’ll see temperatures dropping 10–15°C, they’ll be seasonal to just slightly below seasonal for this time of year.

Fortunately this cold snap will be brief. Early next week it looks like a weak system will move through bringing a chance for some light snow and a return to slightly above-seasonal temperatures.

  1. This is due to the cyclonic curvature of the surface pressure gradient which can act to diminish wind speeds.  ↩

Staying Above Normal; Chance of Snow Midweek

This week will remain seasonably warm, although not quite as warm as last week. There will also be another chance of snow by the middle of the week as a low pressure system pushes up from the south.

Today will be seasonably warm, but mainly cloudy. We’ll be under a breezy north-easterly flow as a strong surface high sits off to our north-east. Temperatures will sit just below the freezing mark with little change throughout the day.

Tomorrow will be mainly cloudy once again, but this time there will be a slight chance of flurries. Any snow that does fall will not accumulate to much. Temperatures will sit in the mid minus single digits with a light easterly wind.

GDPS 24hr QPF valid 06Z December 17, 2015
Just one guess of the snow swath expected with a low pressure system passing by on Wednesday.

A stronger low pressure system is currently forecast to affect southern Manitoba on Wednesday. This will be a Colorado Low type system, which is expected to mainly affect areas to our south, but may also bring light to moderate snowfall to parts of southern Manitoba. At this point it appears that areas along the US and Ontario borders will see the most snow, but it’s too early to speculate on possible accumulations. Stay tuned for more updates.

Long Range

The long range forecast suggests that we’ll continue to slide closer to seasonal temperatures in the short to medium term. That means high temperatures near -10C and low temperatures near -20C. However, ensemble guidance continues to hint at high probabilities of above-normal weather as we move toward Christmas, so any prolonged cold snaps appear quite unlikely through the end of December.

Pleasant Fall Weather Gives Way to End of Week Rain

The weather will be relatively pleasant for late October over the next couple days with above-seasonal daytime highs expected and a fair amount of sunshine. Things will take turn on Friday for the end of the week as a Colorado Low sets its sights on Southern Manitoba and brings a decent shot of rain along with it.

Today will see the cloudy skies that start the day gradually break up and become mixed to partly cloudy. Winds will pick up through the morning and make for a fairly windy afternoon with gusty northwesterlies at 40–50km/h. Today’s daytime high near 12°C will be around 4–5°C above the normal daytime highs for this time of year. Heading into the evening, the winds will taper off and skies will clear as a ridge of high pressure pushes into the province. Expect an overnight low near –2°C.

Thursday will be quite a pleasant day with relatively light winds at 20–30km/h out of the southeast and a high once again near 12–13°C. Clouds will move in overnight as we head to a low near 5–6°C.

Forecast 12hr. precipitation accumulations for Friday from the GDPS
The GDPS is forecasting 10-15mm of rain over Southern Manitoba on Friday.

Friday will see the Colorado Low push into North Dakota and Minnesota, spreading an area of rain northwards into Southern Manitoba. There’s a surprising amount of agreement in the track of the low, but how much rain it will produce seems to be a tough topic. The Canadian Global model, pictured above, shows around 10–15mm through the day on Friday, however I think it’s a bit on the low side. My best forecast at this point is that 10–20mm of rain should be expected through the Red River Valley and southern Interlake on Saturday, however for areas in the RRV south of Winnipeg, particularly closer to the U.S. border, 15–25mm seems like a possibility depending on a number of factors.

Alongside the rain, our daytime high will climb to around 9°C. Winds won’t be too much of an issue and will remain relatively light out of the southeast switching to northwest in the evening. In the evening we’ll see the last of the rain taper off and head to a low near 4°C.

Cooler air looks to push in through the weekend behind the low, so enjoy the milder temperatures today and tomorrow!