T'was the day before a winter storm, and all through our homes, everyone was stirring to make sure their snowblower would go. Perhaps not the best adaptation of the Christmas story classic, but a good indication of what many across the region will be doing today ahead of a multi-day event still on track to bring substantial snowfall and difficult travel conditions. 

A Special Weather Statement remains in effect for all of southern Manitoba as a massive Colorado low begins to impact not only our province, but southeastern Saskatchewan, the Dakotas, and much of the U.S. plains for a good chunk of the remainder of the week. According to Environment Canada, snowfall accumulations will range from 10-20 cm, with some local amounts reaching as high as 30 cm by the weekend.

For the latest Road Report and Cancellation information, click here.

"Light freezing drizzle during the overnight and early morning hours of Tuesday has left a glaze of ice in many areas this morning," noted CMOS Accredited Weathercaster Chris Sumner. "This is the first round of precipitation if you'd like to call it that, associated with this storm. Highways and urban roads are slick, so take it easy on the morning commute."

Sumner noted the risk of freezing drizzle will end by noon, with a cloudy day in store. Snow will develop tonight, and continue overnight into Wednesday morning.

"The revised timeline we started talking about yesterday is still holding, with Tuesday night through Wednesday noon looking like the target for a large portion of the total snowfall from this system," he said. "Current guidance is suggesting upward of 10cms over that timeframe, possibly a little more, depending on whether heavier bands of snowfall go over a certain region. I expect travel Wednesday morning, and throughout the day frankly, to be challenging at best."

He stressed, the Tuesday to Wednesday noon snowfall is just the first round of what could be several waves over the next number of days. In fact, it's likely areas along the international border could see an additional 10cms, or more, from Wednesday afternoon to Friday afternoon.

"This is a very unique Colorado low in the sense most dump the majority of their snow over a relatively short period of time, say 36 to 48 hours," explained Sumner. "Because of the very slow crawl this system will be moving at, due to blocking high pressure to the northeast, we will see an initial dump, but then further accumulations Wednesday afternoon to potentially Friday afternoon as additional waves of precipitation fall over the region. Based on the current forecast models, it's looking very likely we'll see impacts from this storm well into Friday, more than likely a combination of snowfall and blowing/drifting snow."

Somewhat breezy conditions will develop Tuesday, with winds shifting northeasterly Tuesday night at 20 gusting to 40 km/h, and with the expected heavy snowfall rates, that will be enough to cause reduced visibility concerns.

"At this point, I'm not expecting Blizzard Warning criteria to be met, which requires significantly reduced visibility for an extended period of time, but Blowing Snow Advisories could be part of the mix beginning Tuesday night and lasting for the next couple of days, as winds pick up further as this storm system finally starts to drift eastward out of our forecast area," said Sumner. "As the low pulls away, northeasterly winds gusting up to 50 km/h, or more, are expected to develop Thursday and last into Friday night. The additional falling snow over that span, combined with the stronger winds, will mean increased blowing snow impacts.

Environment Canada's Blowing Snow Advisory threshold is when blowing snow, caused by winds of at least 30 km/h, is expected to reduce visibility to 800 meters or less for at least 3 hours. A Blizzard Warning is issued When winds of 40 km/hr or greater are expected to cause widespread reductions in visibility to 400 meters or less, due to blowing snow or blowing snow in combination with falling snow, for at least 4 hours.

Temperatures over the next several days will remain above average for this point in December, with highs between zero and -4 today through Thursday. -9 daytime and -18 overnight are where we should be for this time of year.

"Much colder conditions are on tap for the weekend and early next week, as a trough in the jet stream moves over the region, allowing bitterly cold Arctic air to flood over the eastern Prairies," said Sumner. "We'll start to see that transition Friday as cooler conditions arrive, with highs between -8 and -10, as the storm moves out of the area. The cold air will continue to settle in over the weekend, with the long-range forecast suggesting highs in the -20s are possible by the start of next week."

Related Stories