Tag: Snow

Fall Storm Set to Slam Manitoba With Rain, Snow, and Strong Winds

Brad Leave a comment

A potent fall storm brewing in Alberta will race eastwards across the Prairies today, strengthening substantially as it does. It will move through Southern Manitoba tonight and tomorrow, bringing rain, snow, and strong winds to the region. As it passes, it will also mark a substantial shift in the large-scale weather pattern that will bring much cooler temperatures to Winnipeg over the next week.

Today will be Winnipeg’s warmest day for the foreseeable future as seasonably mild air moves into the region ahead of the incoming low pressure system from Alberta. Temperatures will climb to around the 9°C mark with light northerly winds this morning switching out of the south for the afternoon. Skies will start off partly cloudy to mixed, but more and more cloud will move through the day, making for mainly cloudy conditions this afternoon.

The winds will strengthen in the evening to around 30 km/h as the low approaches, keeping temperatures mild at around 8 or 9°C well into the night. As the centre of the low moves through shortly after midnight, rain will begin spreading into the Red River Valley. Winds will back to the north shortly after midnight and intensify, reaching 40 gusting to 60 km/h by Thursday morning. At this point, we expect precipitation to remain as rain overnight with temperatures dropping to a low near +3°C; between 5 to 15 mm of rain is likely to fall overnight throughout the Red River Valley, with lower amounts near the U.S. increasing northwards towards Winnipeg and the southern Interlake.

NAM Forecast Precipitation Type and Intensity valid 09Z Thursday October 26, 2017
The forecast rain/snow line at 4 AM Thursday morning will cut through the Parkland and into the Interlake

For those further west in the southwest corner of the province or in the Manitoba Parkland, rain will change to snow overnight with lower amounts of 2 to 5 mm of rain and a dusting of snow in the southwest and higher amounts of 5 to 10 mm of rain and 2 to 4 cm of snow. The exception to the snowfall amounts will the along the Riding mountains and western escarpment, where strong northerly winds will enhance snowfall amounts. Localized accumulations of 10 to 20 cm will be possible in these regions.

NAM Forecast Precipitation Type and Intensity valid 15Z Thursday October 26, 2017
The rain is forecast to completely change over to snow in the Red River Valley by 10AM

Rain will transition to snow – potentially fairly heavy at times – early on Thursday morning in Winnipeg and spread southeastwards quickly through the remainder of the morning. Temperatures will drop to around 0 to +1°C through the morning as the northerly winds further intensify to 50 gusting to 70 km/h with the chance for gusts as high as 80 to 85 km/h. The strong winds will combine with the heavier bands of falling snow to produce poor visibilities in blowing snow. Additionally, road conditions will likely deteriorate through the day, although will be very sensitive to temperature.1 By the end of the day, Winnipeg will likely see around 3-6 cm of accumulated snow, however it may end up a little more, or a little less, depending on how much manages to melt.

NAMNEST Forecast 10m Wind Speed valid 18Z Thursday October 26, 2017
Widespread strong winds will be in place across southern Manitoba and the Dakotas

The strong winds will begin to diminish late in the afternoon, and then gradually taper off to around 20 km/h by Friday morning. The snow will ease to a few flurries in the afternoon and taper off by evening. Temperatures will dip to a low near -4°C.

So in summary, for Winnipeg, winds will intensify tonight to 40 gusting 60 km/h as rain moves into the region. Winnipeg can expect anywhere from 5-15 mm of rain tonight, but will switch over to snow early Thursday morning as winds increase further to 50 gusting 70 km/h. The gusty winds will persist through much of Thursday with moderate snow through the morning tapering off to flurries in the afternoon. Snowfall accumulations will be very sensitive to temperature, but it looks like the most likely outcome will be between 3-6 cm of snow, but should more intense bands develop over the city, up to 10 cm could pile up.

Friday will be comparatively pleasant, but cool. Winds will continue to taper off with partly cloudy skies and temperatures climbing to a high near +3°C. The clouds will clear out for Friday night as temperatures drop to a low in the -6 to -8°C range.

Long Range Outlook

The weekend looks like a bit of a mixed bag. Saturday will be cool but pleasant with a high near 5°C, light winds and fairly sunny skies. Things change on Sunday, though, as another low pressure system pushes into the province, bringing more cloud and the chance for more rain or snow.

Winnipeg’s seasonal daytime high is currently 7°C while the seasonal overnight low is -3°C.

  1. If temperatures remain closer to +1°C, roads will likely remain in relatively good shape until the freeze occurs on Thursday night, but if it dips closer to the freezing mark, area highways may become a bit slick through the afternoon. ↩
GFS Forecast Precipitation Type/Rate valid 06Z Thursday October 26, 2017

Mild Fall Temperatures On The Way Out

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The first half of the week will bring seasonal conditions Winnipeg, but the writing is on the wall: a big pattern shift will usher in significantly cooler conditions for the second half of the week and into the next.

The cooler weather begins to arrive today in Winnipeg, drawn southwards across the province behind a low pressure system that passed through overnight. A few remaining showers and cloud will clear out this morning, leaving Winnipeg with mixed skies for the afternoon. Winds will be fairly breezy out of the northwest as a ridge of high pressure builds into the province; light morning winds will build to 40 gusting 60 km/h for the afternoon. Temperatures today will barely budge from this morning, remaining steady near 6 or 7°C through the day. Expect partly cloudy skies overnight with winds diminishing to around 20-30 km/h and a low dipping down to the freezing mark.

Tuesday will be a pleasant and crisp fall day with plenty of sunshine and a high near 9°C in Winnipeg. Winds will be much calmer out with a morning breeze out of the northwest at around 20 km/h diminishing to light midday. Some cloud will spread into Winnipeg later in the afternoon, announcing the approach of the low that will usher in a dramatic change in the general weather pattern.1 Temperatures will drop to a low near 4°C overnight as northwesterly winds move back in and usher cooler air into the region once again.

RDPS 2m Temperature Forecast valid 00Z Wednesday October 25, 2017
A low pressure system moving across northern Manitoba will draw warm air eastwards into the southern half of the province for Wednesday.

Wednesday will be the last day of mild conditions before things take a dive on Thursday. Temperatures will climb to a high near 10°C as skies become cloudy for the afternoon. Northwesterly winds around 15-25 km/h in the morning will taper off to light for the afternoon. As the low pressure system begins pushing into Manitoba in the late afternoon, the chance for showers will increase as an area of rain slumps southeastwards from central Saskatchewan. Temperatures will dip to a low near 2-3°C early Thursday morning as rain moves in overnight.

Long Range Outlook

Thursday looks rather unpleasant with rain likely changing over to snow in the morning as significantly colder air floods southwards behind a strong low moving across southern Manitoba. Temperatures will reach a high in the low single digits with a brisk northerly wind – likely reaching 40-50 km/h – as the snow tapers off in the afternoon.

GFS 850mb Temperature Forecast valid 00Z Thursday October 26 to 00Z Friday October 27, 2017
This animation of 850mb temperatures – approximately 1.5km above the ground – very clearly depicts the colder air moving into the region through the day

The remainder of the week looks quite cool with highs in the low single digits and overnight lows dipping below the freezing mark each night well into next week. The one saving grace will be the cloud cover, ranging from mixed skies to overcast, that will help moderate the temperatures from getting too cold.

This pattern of cooler conditions will continue through much of next week as a persistent west-coast ridge, eastern Canada trough pattern sustains a generally northwesterly flow over the eastern Prairies.

Winnipeg’s seasonal daytime high is currently 7°C while the seasonal overnight low is -3°C.

  1. Some cloud will likely be around in the Red River Valley through much of the day as it comes off of Lake Manitoba and Winnipeg in the northwest wind. Whether Winnipeg sees any of it will depend on the exact wind direction, but it will likely remain outside the city. ↩

Forecast Update for Friday Night and Saturday

Brad Leave a comment

The disturbance that we wrote about in our forecast that went live early this morning is throwing a wrench into things as it has progressed eastwards much faster than models had anticipated, already spreading across southwestern Manitoba into the Red River Valley. This will dramatically change the forecast for Saturday morning and afternoon.

As of writing, the system is producing a line of precipitation extending from the Manitoba/Saskatchewan/North Dakota border east-northeast along a line that runs just through Boissevain and Deloraine into the Red River Valley. Much of the precipitation from this line is currently falling as rain, however snow is likely mixing in on the northern edge of the band, where temperatures have dropped towards the freezing mark.

HRRR Forecast Accumulated Precipitation valid 17Z Saturday October 14, 2017
The forecast total precipitation amounts from 9PM October 13 to 12PM October 14 reveal the narrow band that the rain/snow is expected to fall along.

Precipitation will push east-northeast throughout the night, however where it is expected to be heavy enough to accumulate in any meaningful way will lie along a very narrow band roughly located where the heaviest of the precipitation is as of this writing.

Much of this will likely remain as rain; there’s a fair amount of warm air aloft and temperatures are being maintained around 2-4°C underneath the precipitation. As mentioned before, some snow will likely mix through as it progresses eastwards, but no significant accumulations are expected.

Over the heaviest band in the southwest corner of the province, it will likely be a decent soaking, however, with 10-20 mm of rain possible.

Shift Southwards Spares Southwestern Manitoba From Snow

With the shift southwards, the southwest corner of the province will be spared from the 5 to 10 cm we suggested was possible in our earlier forecast. The closer proximity to the border has the precipitation falling in warmer conditions, causing that snow to fall as rain instead.

Winnipeg On The Edge

The forecast for Winnipeg continues to be difficult, with the city likely resting right on the northern edge of the precipitation. It seems most likely that the city will see some rain or snow beginning around 2 to 4AM and tapering off by 7 to 8AM. No significant accumulations are expected.

Still A Chance for Afternoon Showers

This disturbance won’t be completely gone for Saturday afternoon, with a chance for showers re-developing over the Red River Valley mid- to late-morning and persisting until mid-afternoon. Temperatures will be warm enough that snow won’t be a concern, but 2-4 mm of rain will be possible under the “heaviest” band of showers. The chance for rain should remain south of Winnipeg.

Slightly Warmer Highs Expected

With the shift in timing for this system, daytime highs will be slightly higher than we forecast earlier. With the higher intensity precipitation finished by mid-morning, highs will be able to climb a bit warmer into the 6 to 8°C range instead of near 5°C like we advertised before.

The faster and more southerly arrival of this system means that the daytime hours on Saturday will see less precipitation than expected and allow daytime highs to climb a bit warmer. The heaviest amounts will fall along a narrow band in the southwest corner of the province with 10 to 20 mm possible through the and Saturday morning. The precipitation is largely falling as rain instead of snow, thanks to the slightly warmer temperatures aloft due to the shift southwards of this disturbance’s track.

Hopefully this covers what to expect; sometimes these systems progress a bit unexpectedly and all model guidance just…fails. This is one of those cases. We think the newer runs of rapid-update models are getting a good handle on it, though, so hopefully this forecast is able to hold up a bit better than the last one.

Saturday Brings First Snowfall of the Season

Brad Leave a comment

A low pressure system tracking along the U.S. border will bring a mix of rain and snow to southern Manitoba on Saturday, and while the Red River Valley may see a few slushy centimetres, higher accumulations of 5 to 10 cm will be possible over the southwest corner of the province. The snow will be short-lived, however, as above-seasonal temperatures are set to return next week!

Models took a quick turn after our Wednesday forecast with a dry weekend quickly turning…not so dry as they picked up on a disturbance that will track along the US border and likely bring rain and snow to southern Manitoba on Saturday. Before that, though…

Today will be a cool but beautiful day! Winnipeg will see sunny skies and westerly winds at around 15 to 25 km/h as temperatures climb to a high near 10°C. Cloud will begin pushing into the Red River Valley tonight, bringing a chance for some rain showers to Winnipeg before morning. Winds will be calm as temperatures dip to a low near 2°C.

3km NAM Forecast Precipitation Type and Intensity valid 18Z Saturday October 14, 2017
Rain showers will give way to snow from northwest to southeast across the Red River Valley on Saturday. Winnipeg will likely see the changeover occur midday.

Southern Manitoba will see a mix of precipitation through the day on Saturday. The biggest question of the day will be where the rain/snow line will set up, and right now it appears that Winnipeg will straddle that line, with a few morning showers either mixing with or changing over to snow midday. Fortunately, with near-zero temperatures, any snow will be unlikely to accumulate too much through the city, with just a slushy couple centimetres possible. Further to the west and north, more substantial snowfall is possible, with 5-10 cm possible along a line from around Estevan, SK to Virden, MB to Lake Manitoba.

We’ll definitely post an update later tonight with a revised snow/rain forecast for Saturday.

Aside from the precipitation, expect to see temperatures climb to a high just near 5°C with northeasterly winds of 15 to 25 km/h. Temperatures will dip down to around -2°C with some clear breaks overnight.

Sunday will see conditions improve, with mixed skies and a light west-southwest wind as temperatures climb to a high near 10°C. Temperatures will drop to a low slightly above freezing.

Long Range

Next week is looking fantastic for those who aren’t quite ready for the latter parts of fall. Warmer air is expected to spread eastwards across the Prairies, and while there may be a disturbance or two with a brief cool-down associated with it that moves through, temperatures will tend to remain above-seasonal.

GDPS 850mb Temperature Anomaly valid 06Z Friday October 20, 2017
Very mild air will spread eastwards across the Prairies through next week, with significantly warmer-than-seasonal temperatures (red, brown) possible at the end of the work week.

Daytime highs in the mid- to upper-teens will be common through the week, alongside variable cloudiness and few chances for rain as the main storm track appears to remain in the central and northern Prairies.

So make it through a bit of an unpleasant Saturday, and a beautiful mid-October week lies ahead.

Winnipeg’s seasonal daytime high is currently 11°C while the seasonal overnight low is 0°C.