Tuesday morning temps more than 20 degrees warmer than average

Warm westerly winds that started on Monday night continued into Tuesday, elevating morning temperatures in many southern Alberta communities.

As of 6 a.m., it was already 9 C in Calgary, compared to a normal overnight low of -12 C.

Westerly winds are expected to peak around 30 km/h in Calgary Tuesday morning with gusts closer to 50 km/h, but a developing lee trough will interrupt this pattern by the early afternoon.

A lee trough is a low pressure system that forms on the leeward side of a mountain range, or in this case, on the Alberta side of the Rockies.

This low will go on to become a classic “Alberta clipper” - a fast-moving weather system associated with unsettled conditions east and south of Alberta.

Colder air will mix with precipitation overnight Tuesday and the morning commute in southern Alberta on Wednesday may include freezing drizzle and/or fog.

This disturbance will be brief with warmer air returningon Thursday and continuing until Saturday.

With sunshine most days and the enhanced evaporative qualities of a westerly flow, a freeze-thaw cycle will emerge in Calgary, meaning sidewalks and parking lots will likely become icy in the overnight periods.