Tag: Rain

Messy Winter Weather Continues

Brad Leave a comment

Winnipeg hasn’t see the last of the snow quite yet; after a mix of snow and rain yesterday, another mess of wintery weather is on the way later today as a low pressure system slumps through the province from the northwest. Afterwards, the Red River Valley will be left with generally cool weather with daytime highs below seasonal values.

Winnipeg will see but a brief reprieve from yesterday’s snowy & slushy weather before another low pressure system pushes into the province from Northern Saskatchewan and brings another shot of rain and snow to Southern Manitoba. Before that wet and messy weather moves in, Winnipeg will be stuck under mostly cloudy skies with light winds. Temperatures will be below normal today with daytime highs near +3°C.

RDPS 6hr. QPF valid 06Z April 7, 2016
The RDPS shows an area of precipitation moving across the Red River Valley on Wednesday evening

By late this afternoon, a mix of rain and snow will begin working its way into the Red River Valley from the northwest. This mix of precipitation will likely continue into the evening before changing over to just snow overnight as temperatures dip to a low near -3°C.

As the low pressure system passes to the east of the Red River Valley overnight, stronger northwesterly winds will develop with sustained winds of 30-40km/h and gusts to around 50km/h.

Thursday will bring more cloud to the region with the gusty northwesterly winds continuing throughout the day, sustained by a ridge of high pressure building in from the north. There will be a chance of light flurry activity throughout much of the day, but no significant accumulations are expected. The daytime high will be a bit cooler than Wednesday at +1 or +2°C, but as the ridge moves it brings much cooler air. It will be noticeable on Thursday night as the winds drop off and Winnipeg heads to a low near -10°C.

The sun should finally make an appearance on Friday as the weather over Southern Manitoba is dominated by a ridge of high pressure. This will result mainly sunny skies with light winds and very cool daytime highs[1] in the low minus single digits. Friday night will continue to be cold with an overnight low in the minus teens.

Long Range

Looking ahead to to the weekend and beyond, it appears that the generally cool temperatures will stick around until at least the middle of next week before a return to more seasonal values.

CPC 6-10 Day Temperature Anomaly Forecast valid April 11-15, 2016
The CPC is forecast below-normal temperatures for Southern Manitoba in the 6-10 day time period

The weekend looks like the most "active" period in the longer-range forecast as another significant low pressure system moves across the Prairies. Strong southerly winds will develop ahead of the low as it moves towards Manitoba through the day on Saturday[2], and then as they begin to diminish another mix of rain and snow will spread across portions of central and southern Manitoba. There’s uncertainty as to how much Winnipeg will see, but best indications are that most should stay north of the city.

Otherwise, the weather looks cool and calm through the first half of next week.

Winnipeg’s seasonal daytime high is currently 7°C while the seasonal overnight low is -4°C.

  1. Friday’s daytime high will be nearly 15°C below seasonal values!  ↩
  2. Sustained winds of 50 km/h are possible on Saturday with gusts as high as 70 km/h.  ↩
NAM Simulated Reflectivity valid 18Z Tuesday March 15, 2016

Major Storm System Looms

Scott 1 Comment

We’ll see one more nice day today before a potentially significant weather system affects us on Tuesday and Wednesday. Rain and snow is expected in southern Manitoba with this system, but exact amounts remain unclear.

Today will be another very nice day. Temperatures will climb into the mid teens over much of southern Manitoba, allowing our snow melt to continue. Many rural parts of southern Manitoba are already snow-free, but there is still snow to melt in sheltered areas. Skies will be mainly sunny, with breezy south-east winds.

A major low pressure system will affect southern Manitoba this week
A major low pressure system will affect southern Manitoba this week

A major low pressure system is expected to affect southern Manitoba on Tuesday and Wednesday. This system will bring a combination of rain and snow, which makes it difficult to forecast. At this time it appears that rain will be the main mode of precipitation over the Red River Valley. Models disagree widely on potential accumulation, so it is difficult to say exactly how much rain will fall. A “best guess” is that Winnipeg will see about 5-15 mm of rain. More or less rain could fall depending on how the system evolves.

We will continue to be under the influence of this system on Wednesday, but temperatures will fall as we experience a stiff north-westerly flow. As a result of this cold air surging in from the north, rain is expected to change over to snow, with a couple centimetres of accumulation being possible. The exact amount of snow will depend on how much the system stalls over our area and how much cold air manages to infiltrate southern Manitoba. High temperatures on Wednesday are currently expected to be near 2C, which would not favour large accumulations.

Long Range

The end of the week is expected to be colder as the system from earlier in the week pulls down colder air from the north. Longer range models suggest that the second half of March will see a cooler pattern with outbreaks of colder arctic air. However, if we remain mainly snow-free following this week’s system, it will be difficult for very cold conditions to last long as the darker soil will be able to absorb much more sunlight than snow would.

Mild Friday Leads to Cooler Weekend

Brad Leave a comment

The mild weather will continue today with daytime highs of +1 or +2°C today as yet more warm air washes over Southern Manitoba. The system responsible for this mild spell will be making its way across the region today and after it brings some mixed precipitation, it will push eastwards into Ontario, taking the warmth with it. Northerly winds will develop tonight and begin to usher in cooler, more seasonal temperatures.

Today will bring some more organized precipitation across the Red River Valley as the main disturbance that’s been responsible for the warmth this week moves across the region. With temperatures so close to the freezing mark, what type of precipitation will be falling is a bit of a difficult question to answer. Looking at the Red River Valley as a whole, we can say that there will be mixed precipitation, however for any one location may see just rain, just snow, or both. Even if snow falls, with the above-0°C temperatures, it won’t be able to accumulate much. By the time the precipitation tapers off, just 1-2 mm of rain or cm of snow will have fallen.

With light winds and above-zero temperatures, it also is possible that drizzle or fog patches are an issue throughout much of the day.

As the system moves into Ontario later today, northerly winds will begin developing over Southern Manitoba and draw in cooler air from the north. Drizzle or freezing drizzle will be possible through the early evening hours, but that risk should dissipate heading into the overnight period. Temperatures will dip to about -6°C with gusty northerly winds up to 30 km/h.

GDPS 850mb Temperature Forecast
The GDPS shows the gradual return of colder air via 850mb temperatures.

Saturday will bring mixed skies and diminishing winds as the Red River Valley sees a weak ridge of high pressure begin to build in. There’s a bit of uncertainty to exactly how much cloud will clear out of the region; it will likely trend towards cloudier, but we should see a few sunny breaks through the day. Temperatures will recover just slightly from the overnight low to a high of -5°C. The colder weather will continue pushing southwards with gradual clearing through the evening & overnight that will allow temperatures to dip to an overnight low near -17°C.

Sunday will bring partly cloudy skies to Winnipeg, but the southern Red River Valley will likely see cloudier skies as a weak low pressure moves through North Dakota. This system will produce some light snow for areas further south, but in Winnipeg there will just be a chance of flurries. Temperatures will be slightly cooler than seasonal with a high of -12°C. Skies should clear on Sunday night as temperatures head to a low near -16°C.

Long Range: Not Cold For Long

This cool-down will be brief; by Monday daytime high temperatures approaching the freezing mark will return to the Red River Valley.

Temperatures will be variable next week with warm days giving way to 1-2 days of seasonal temperatures before warmer weather returns again. No significant precipitation events are expected through next week.

Winnipeg’s seasonal daytime high is currently -7°C while the seasonal overnight low is -18°C.

Mild Weekend Then Into A Colder Stretch

Brad Leave a comment

A low pressure system crossing the Prairies will bring another wave of unseasonably mild air into Southern Manitoba and help temperatures climb above 0°C for the second time this week. Heading into the latter half of the weekend, unsettled weather will develop over Southern Manitoba bringing flurries as cooler air begins gradually slumping southwards out of the Arctic and across the Prairies.

Today will be a much nicer day for Winnipeg than it appeared like it would be earlier this week, all thanks to a more northern track for today’s low pressure system crossing the province. As a result of this trajectory, Winnipeg will still see the warmth we expected before, but much less of the precipitation, which will now mainly fall through Central Manitoba and the Interlake before heading off into Ontario.

For the city, today will start off with a chance of…well, just about anything—snow, freezing rain, or showers—as a warm front pushes through and brings our temperatures above zero. As the warm front pushes off to the east relatively early in the day, we’ll be left with skies on the cloudier side and temperatures in the +1-2°C range. Windswe will start out of the south at around 30-40km/h before shifting to westerly behind the warm front at similar speeds. The chance for showers will redevelop mid-day and through the afternoon as a little bit of cooling aloft moves across the region. Expect temperatures to drop to around -2°C tonight with a few clear breaks developing.

RDPS 12hr. QPF Forecast for Friday January 29, 2016
This RDPS forecast showing accumulated precipitation through Friday shows how most of the precipitation is expected to our north and east

Saturday will bring more warm weather cloudier skies once again, although a few sunny breaks are certainly possible and the southwestern Red River Valley may actually end up seeing a fair amount of sunshine. Temperatures will climb to around +1°C with lighter winds than Friday.

A cold front will begin slumping southwards through the region on Saturday night. This will bring cooler temperatures and send our overnight low down to around -11 or -12°C under cloudy skies. Alongside the cooling will be a chance of some light flurry activity.

Sunday will be a cooler day with a high in the near -6°C or so. Under mainly cloudy skies, Winnipeg will see a slight chance for flurries throughout the day thanks to favourable temperatures throughout the lower atmosphere. This cooler weather will mark the leading edge of a return to seasonal and below-seasonal temperatures for a short while.

Long Range: Colder, But For How Long?

Looking forward into next week, it looks like cooler weather will return to the Prairies as the conditions that have supplied the warmer weather to the region over the past week collapse southwards and allow cooler Arctic air to slump southwards.

GEPS Maximum Temperature Forecast valid February 1-6, 2016
GEPS maximum temperature forecasts valid for the February 1-6, 2016 time period

The GEPS[1] is showing a transition into slightly below normal conditions next week. This image shows the maximum temperature expected in each 6-hour time period from Monday through Saturday. Ensemble forecast systems produce numerous forecasts, and then statistical analysis can be done on the output to (in theory) produce more accurate forecasts, especially in the long range. In the image above, the easiest way to understand it is that the value along the line is a fairly reasonable "most likely" temperature, while the red shading on either line represents the certainty; if there’s little shading extending from the line that means there is high confidence in the values; if there’s a lot of shading extending above and below the line, it means that there’s more uncertainty associated with the forecast at that time.

The GEPS shows fairly reasonable confidence that daytime highs will be dropping into the -15 to -20°C range early next week, a fair amount below the seasonal highs of -11°C for this time of year. With daytime highs in that range, it’s likely overnight lows will dip into the mid-minus 20’s. Heading toward the end of the week, though, there begins to be a lot more uncertainty on the weather pattern, so we’ll just have to wait and see for when the warm-up returns!

  1. Global Ensemble Prediction System  ↩