Small Disturbance Today; Significant Colorado Low This Weekend

There will be a very slight chance of showers today as a low pushes across the Interlake region, however the bigger news will be this weekend, when a powerful Colorado Low ushers in winter over Southern Manitoba.

The rough track of the upcoming Colorado Low

A satellite image showing the current position and estimated track of the Colorado Low that will impact Southern Manitoba this weekend.

A low pressure system track through the Interlake today will bring 10-15cm of snow through Central Manitoba, north of the track of the low. Through southern Manitoba, there will just be a slight chance of a shower through the afternoon and evening as most areas see a mainly cloudy day with a high near 3 or 4°C. There’s a slight chance to see some sun across many areas this morning, however the likelihood of fog development in any clear areas may mask the chance for sunshine.

Thursday will bring some sunshine and a windy morning, with winds gusting out of the N/NE to 30 or 40km/h behind the system, but should lighten into the afternoon. Temperatures will be cooler than late, with highs only around -1 or 0°C.

By Friday, we’ll begin to feel the impact of the Colorado Low. Winds will begin to pick up out of the northeast as snow begins pushing into SW Manitoba. Snow will make it’s way into the Red River Valley overnight, with steadier snow developing Saturday morning. Disagreement still exists amongst the model runs as to where the heaviest snowfall will be, however the NAEFS (North American Ensemble Forecast System) has been startling consistent over the past few days with painting the heaviest snowfall right over Winnipeg.

Probability of > 10cm of Snowfall

Probability of ≥ 10cm of snowfall from the NAEFS, valid from 12Z November 10th to 00Z November 11th (a 12hr. accumulation).

The NAEFS is showing significant confidence in areas in Southwest Manitoba (Melita, Pilot Mound, Virden and Brandon) regions seeing more than 10cm of snow, with a decent likelihood of people west of the Red River seeing ≥ 10cm as well. North of the Trans-Canada highway, it looks like from Portage to Winnipeg has a sizeable chance of seeing greater accumulations, as well as into the Southern Interlake.

Snow will taper off on Sunday, however significant accumulations will likely have developed in it’s wake. Current indications are that the SE corner of the Red River Valley will see the least snow, and accumulations will increase as you head west and north. In addition to the snow, gusty winds to 50 or 60km/h will push into the Red River Valley as well, producing widespread reductions in visibility due to falling and blowing snow. System-total precipitation looks to be 15-25mm, which when taking into account the expected SLR (snow-to-liquid ratio) of around 10:1, would result in a total of 15-25cm of snow. General estimates for accumulated snowfall by the end of the weekend for a few select sites are:

  • Winnipeg: 15-20cm
  • Steinbach: 10-20cm
  • Morden/Winkler: 15-25cm
  • Portage la Prairie: 15-25cm
  • Brandon: 10-20cm
  • Pilot Mound: 15-25cm
  • Sprague: 5-15cm
  • Victoria Beach: 10-20cm
  • Gimli: 10-15cm

We’ll have more updates on the track of this system as the week progresses. Monitor EC’s Weather Office site for forecasts and any watches or special weather statements as the week progresses. Although the exact timing and intensity of this system may be difficult to pin down, it’s a safe bet to say that driving conditions will likely be extremely poor with ice-covered roads and low visibilities in blowing snow. Conditions in North Dakota will also be quite poor as well this weekend. If you have plans to travel by car/truck this weekend, be sure that you’re prepared for the hazardous weather that will be present. Always carry a winter survival kit in your vehicle if you must travel during winter storms.

Wet & Windy Weather On The Way

Yesterday’s beautiful mid-October weather will be replaced in a hurry today and tomorrow, as a intense 985mb low pressure system brings unsettled weather into the Red River Valley with strong winds moving across the area as the low pushes eastwards.

RDPS 3hr. QPF for this afternoon.

3-hour accumulated precipitation for mid-afternoon from the RDPS. Precipitation will be oriented in a band NW-SE ahead of the main surface trough.

Cloudy skies will be dominant over the Red River Valley over the next couple days. While temperatures are fairly mild this morning, and of note is how high our dewpoint has climbed, we won’t gain too much temperature-wise through the day today. Showers will push into portions of the Red River Vally & SE Manitoba this morning, however it’s likely that precipitation will be sporadic for any one location through the day today with fairly minimal accumulations. Conditions don’t look too favourable for drizzle today; you generally want saturated low-levels of the atmosphere with a sharp contrast into dry air immediately above the cloud deck for drizzle generation. Today, we’ll actually have dryer low-levels with a fairly moist atmosphere above, so it’s more likely that any light precipitation would be somewhat-evaporated rain, not drizzle. Temperatures will climb to 12 or 13°C today.

A band of steady rain will begin to push into the Red River Valley this evening as an area of strong frontogenesis1 on the northwest side of the 850mb low orients itself over the region. The band of rain looks to be fairly narrow, and positioning of it will be very sensitive to the positioning of the 850mb low. All areas in the Red River Valley will see some periods of rain tonight, however any locations that end up under this sharp band of rain will likely see 5-10mm of rain. Amounts remain low, despite the strong forcing, as this system, while energetic, is relatively low in moisture. Precipitable water values look to be only in the 20-25mm range, instead of the closer to 40-50mm range we look for for higher-accumulation rainfall events.

Winds will pick up overnight into Thursday as the Red River Valley moves into a strong pressure gradient on Thursday. Winds will climb to 40-50km/h with gusts up to 60km/h. Showers will be widespread through the Valley as general “wraparound” precipitation moves in on the backside of this system. Total amounts for tomorrow will generally be 4-8mm across the Red River Valley. The rain and wind will taper off tomorrow night as the system moves off towards the Great Lakes. Temperatures will drop down to 6 or 7°C.

Friday will be a slow recovery day, as the clouds will begin to break up a bit through the day. With skies remaining fairly cloudy with only a few breaks for sunshine, temperatures will end up fairly steady through the day; likely only around 8°C. Looking ahead to the weekend, it looks to be a fairly seasonal weekend with a mix of sun and clouds and highs near the seasonal 10°C.

  1. From the AMS Glossary: In general, an increase in the horizontal gradient of an airmass property, principally density, and the development of the accompanying features of the wind field that typify a front. 

A Windy Day to Mark Arrival of Warmer Air

Winds will pick up today out of the south as warmer air finally begins to push it’s way into Southern Manitoba. By this afternoon, strong winds will be in place over the Red River Valley and temperatures will finally climb out of the single digits under an extensive cirrus cloud deck.

NAM Skew-T Log-P Digaram

NAM-based model Skew-T Log-P diagram for the central Red River Valley valid at 21Z this afternoon.

Winds will pick up by early this afternoon as a warm front pushes across Southern Manitoba. Sustained wind speeds will increase to 50-60km/h, with strong gusts on top of that; mostly around 70km/h, but the potential exists for gusts as high as 80-85km/h.

The picture above is a model-based skew-T log-P diagram which shows how temperature (red line) and moisture (green line) change with height in the atmosphere over a single location. Up the right-hand side of the chart are wind barbs, which represent the wind speed & direction at that height in knots. Each full tick mark is worth 10kt, a half tick mark is worth 5kt, and a filled triangle is worth 50kt. On the left hand side, the pressure is marked from 1000mb (the surface) to 100mb (about 16km off the surface). In the skew-t log-p diagram above, we can see a strong 20kt flow out of the south with an unstable layer from the surface to about 875mb. Within this unstable layer, near the inversion, winds increase to 45kt. Since it’s within mixing distance of the unstable layer, it’s entirely possible that those strong winds could be mixed down to the surface.

Temperatures will climb to about 10°C today, but with that strong wind it’s going to feel a little cool out there this afternoon. The winds will taper off this evening as things cool off, and then we’ll enter into a fairly pleasant weekend.

We’ll be under the influence of a weak low pressure system through the weekend, however unlike most systems, very little precipitation will occur near the system; instead most of the precipitation will be displaced northwards, into the high Interlake region, where frontogenetic forcing is stronger. What that means for us, fortunately, is that we’ll see relatively light winds through the weekend, a mix of sun and clouds and daytime highs in the low-to-mid teens. Overnight lows will be bumped up a little bit from the -3 to -5°C range to just at or above 0°C.

This weekend will be a pleasant break from the cold. Best to get out and enjoy it too; next week looks to bring multiple systems that could bring us some more rainy, windy weather.

Major Cool Down Begins

A significant change in the weather is underway today as Arctic air blasts southwards, pushing out the pleasant, above normal temperatures we’ve had lately and replacing it with cloudy, cool, windy weather. I hope you enjoyed the last few days, because you probably won’t enjoy the next few.

850mb Temperatures from the GFS

850mb temperatures valid this morning from the GFS model. Warm and cold fronts are depicted.

A cold front, tied to a powerful low pressure system moving through central Manitoba, swept across the Red River Valley overnight, ushering out the warmer temperatures aloft that have given us pleasant temperatures the past few days. In it’s wake is a dramatically different pattern than we’ve seen lately.

Upper troughing will dominate the Prairies as a secondary low, currently spinning up over Montana/Wyoming tracks eastwards and pulls more cold air southwards. This will establish us into a much cooler pattern where cooler, Arctic air is entrenched over the region and it’s significantly harder for us to get those nice warm breaks.

Today we’ll see winds begin to pick up out of the north as temperatures climb to only around 13°C. We’ll get cloudier as the day goes on, and by the late afternoon into the evening some showers will push into the southern regions of the Red River Valley. Further north, we’ll see a chance of showers, however it will be more difficult for any organized precipitation to develop over the northern Red River Valley.

As the aforementioned US low tracks through South Dakota, winds will shift to the north-northeast over the RRV, which when combined with the cooler air being dragged southwards, will bring lake-effect showers into the central Red River Valley. Current model solutions hint that Winnipeg may be in the path of these, however, as usual, the exact wind direction will be crucial in determining where the showers will fall. Temperatures will drop to around +3°C tonight.

Thursday will be a cool day, with northerly winds persisting, cloudy skies and a high of only 7 or 8°C. Lake effect showers will persist in the lee of the lakes, and scattered showers will likely be found throughout the entire Red River Valley. Cold air continues to pour southwards and we’ll drop to near 0°C. Precipitation is…complicated for Thursday night. The GEM-GLB & GFS models are forecasting only around 5mm of rain for Thursday evening over SE Manitoba, including the Steinbach region. Other models, such as the NAM, have a much worse forecast. The NAM spins up the low over the states into a very powerful storm system, which taps into some Gulf moisture over the east-central States and lifts it northwest and slams it into a deformation zone oriented north-south over the Red River Valley. In this outcome, 1-2 inches of precipitation is forecast to fall, some as rain, however much of it as snow. Should we believe the NAM, it would result in many communities east of the Red River waking to find over a foot of snow on the ground! Ensemble forecasts suggest that this is an outlier; most solutions favour a quicker track to the low with less precipitation over the Red River Valley. We’ll keep a close eye on this as it develops, but you should be prepared for the potential for poor travelling conditions on Friday.

Things calm down on Friday as this system leaves the region and we’ll be left with cloudy skies and a high around 10°C. Things look to improve a little bit for the weekend (e.g. we may see the sun), but temperatures will remain locked in the high single digits to low teens as cold, arctic air remains entrenched over the region.