Southern Manitoba will be under an increasing risk of thunderstorms as the week progresses. Heat and humidity will slowly build back into the region as a deep upper trough begins to build over the Rocky Mountains before tracking eastwards across the Prairies later in the week.

We’ll see warmer temperatures today as warmer air pushes in behind a warm front that passed through overnight. Daytime highs should be near the 25°C mark through most of the RRV. By this afternoon a weak frontal wave will be positioned near the international border with a trough extending NW to a low pressure system tracking into Western Manitoba. Showers and thunderstorms will develop over SW Manitoba early this afternoon and slowly develop northeastwards into the Red River Valley. It will mainly be regions through the northern Red River Valley that face the risk for showers or thunderstorms (Portage la Prairie, Winnipeg, Selkirk; as seen in the image above). The showers and thunderstorms will lift northwards into the Interlake overnight while overnight lows drop to the mid-teens over most of Southern Manitoba.

Opinions differ for Thursday, however it’s generally expected that a north-south band of showers with a chance of an embedded thunderstorm will develop over the Red River Valley or the Whiteshell in the afternoon. This line will slowly move eastwards and intensify into a band of thunderstorms. Again, there’s still quite a bit of uncertainty to where this line will develop, and the potential exists for fairly large (close to 1”) rainfall accumulations. We’ll be keeping close track of this system’s development.

Friday looks to be a fairly nice day with comfortable humdity and daytime highs in the mid-20’s. A large MCS is forecast to develop on Friday night in North Dakota, bringing the chance for a stormy and rainy Saturday. We’ll take a closer look at that system later this week.