A strong Alberta clipper system is moving across northern SK today ushering in a gusty southwest flow of very mild Pacific air over southern AB and southern SK. Temperatures have soared into the mid teens over southern AB with several record highs established for December 1st. This warm airmass will be moving towards southern MB over the next 24 hours, but the bulk of the mild air will be bypassing to the south of Winnipeg into the Dakotas overnight. Even so, gusty south winds tonight of 40-60 km/h will bring rising temperatures overnight to the Red River valley, with temperatures expected to climb towards the freezing mark by daybreak. In fact, there's a chance we may get above zero (+1 to +3C) for a brief period early Tuesday morning as our winds shift into the west and tap some of the retreating mild airmass over southern SK. Regardless, the mild temperatures will be short lived as strong northwest winds develop behind the clipper system Tuesday, and bring increasingly colder air through the day. So watch for temperatures to fall Tuesday, especially in the afternoon and evening as those northwest winds pick up.
As for precipitation with this system, it looks like Winnipeg may get a period of snow tonight with a risk of freezing rain or ice pellets overnight as the warm front approaches. The bulk of the snow should remain north of Winnipeg through the Interlake and central MB, but we could see a couple of cm tonight. If any freezing precipitation develops, the best chance will be between 10 pm and 4 am, but amounts should be light. Nonetheless, road conditions could be on the slick side Tuesday morning as this system moves through with some mixed precipitation and near freezing temperatures. Look for windy and colder conditions by Tuesday afternoon with occasional flurries giving a dusting to 2 cm over Winnipeg and the Red River valley.