More thunderstorms possible Wednesday with heavy rain starting Friday

Another chance of thunderstorms on Wednesday. Jodi Hughes has a look at the five-day forecast from the Sky Watch Weather Centre.

As expected, showers and thunderstorms rolled through southern Alberta Tuesday afternoon prompting severe thunderstorm warnings across the region.

A similar situation is possible on Wednesday, with thunderstorms initiating off of the foothills before tracking slightly north and mostly east.

There is also a risk of thunderstorm development across northern Alberta and in the southeast portion of the province on Wednesday.

Today’s forecast includes enough available energy and wind shear within the atmospheric profile that there is a chance of supercell development.

The greatest threats from these storms include large-sized hail and strong wind, however funnel clouds and/or tornadoes can not be ruled out.

The other big weather story is an increasing likelihood of a prolific amount of rain expected to impact southern Alberta starting Friday.

An intense low pressure system from the Pacific basin is on track to stall out over the southern B.C. border by Friday, held in place by an even stronger low complex in northern Canada.

This will allow persistent moisture to funnel in to southern Alberta, circulating counterclockwise around the Pacific low and creating an upsloping scenario whereby the Rocky Mountains serve as a topographical barrier and enhance precipitation accumulations east of the foothills.

At the high end of forecast rainfall totals Calgary may see up to 90 to 100 millimetres over a few days, with more conservative estimates closer to 70 millimetres.

June is typically the wettest month of the year in Calgary, with a 30-year average of 112.7 millimetres of precipitation over the month, or one-quarter of the annual precipitation for the city.

This week’s rainfall event will also coincide with the 12-year anniversary of the 2013 floods.

Temperatures will also drop over the weekend when colder air from the west edge of the northern low flows toward Alberta’s southern border producing windy conditions.

Daytime highs in Calgary over the weekend will likely be around 10 degrees below seasonal.