Unsettled start to the weekend with both frost and funnel clouds possible

Friday will be a buffet day of weather – with southern Alberta experiencing fog, sunshine, clouds, rain, thunderstorms, potential funnel clouds, and frost.

Patchy fog is likely early Friday due in part to very light wind, allowing the air just above the surface to become saturated from normal overnight evaporative processes.

A surface trough in eastern British Columbia will help trigger instability along the foothills where afternoon thunderstorms could develop.

Upsloping associated with a frontal system producing active weather in the Midwest and a strong low in the Dakotas could provide wind shear, and all of the above may combine to aid in funnel clouds development along the Trans-Canada corridor later in the day.

As a more regular west-to-east weather pattern returns overnight the skies will be more clear than they have been, and that, along with cooler maximum temperatures and higher soil moisture levels could lead to frost overnight in some communities.

Saturday will be similar to Friday with a risk of showers and thunderstorms expect with higher rainfall totals possible in affected areas.

With rain on Thursday and early Friday Calgary has now had rain on 18 of 24 days in May, or 75% of the days in this month.

May is typically the start of the wet season in Calgary, and the fourth wettest month of the year (June, July and August – in that order – are the months that bring the most precipitation to the area).

As of May 23, Environment and Climate Change Canada reported 50.6 millimetres of rain so far this month, which is still below the 30-year average (56.8 millimetres) for the May monthly total, but on track to exceed that total by month’s end.

Daytime highs will creep closer to seasonal Sunday and Monday, but this will be short-lived.

By Wednesday and Thursday the daytime highs are expected to drop back down to 14 C to 17 C.