Today marks the start of an extended period of seasonably cold conditions for Winnipeg.
A low pressure system skirting along the International border will bring cloudy conditions to the Red River Valley today. It will spread an area of rain across the region with up to 10 mm possible along the border. Amounts will quickly diminish northwards, though, with just a bit of light rain likely this morning in Winnipeg. Behind this low, a brisk northerly wind near 30 gusting 50 km/h will develop and usher in a much cooler air mass. Temperatures will only reach around 8 °C today, already several degrees below the seasonal average of 11 °C. The cloud cover will break up a bit tonight as the winds gradually ease. The city will see a low near -3 °C. Hard freezes will be common from here out.
From Thursday forwards, the region will be under a northwest flow aloft on the back side of a persistent vortex over Hudson Bay. This will result in a continued feed of cold Arctic air southwards into the region. Thursday and Friday will bring daytime highs successively colder at +4 and +2 °C respectively. Overnight lows should hover in the mid-minus single digits. Both Thursday and Friday will bring partly cloudy skies to the city and winds will gradually ease from around 30–40 km/h on Thursday to around 20 km/h on Friday. Other than the chance for some lake-effect rain showers or snow in the lee of the lakes — more likely Lake Winnipeg than Manitoba — conditions should stay dry.
Long Range Outlook
The long-range outlook shows nothing but a big vortex entrenched over Hudson Bay. As a result, it also shows nothing but seasonably cold weather for Manitoba. Forecasts show daytime highs locked at the low single digits and overnight lows hovering within a couple degrees of -5 °C.
The cooler weather towards this coming weekend may end up producing lake-effect snow in the lee of Lake Manitoba in addition to Lake Winnipeg, particularly Friday night into Saturday.
Temperatures may begin to moderate towards seasonal values slightly next weekend (October 24–25), but confidence is low right now.
Today’s seasonal daytime high in Winnipeg is 11 °C while the seasonal overnight low is 0 °C.