Mixed precipitation early Tuesday creates icy conditions for mountain passes early Tuesday

Another 14 Alberta communities set new maximum temperature records Monday, including Banff, Sundre, Crowsnest and Waterton areas.

Conditions were so warm that overnight precipitation coming from British Columbia was falling as rain early Tuesday, however certain regions ended up with mixed precipitation and even freezing rain.

Around 7 a.m. Tuesday, police reported a closure in the eastbound lanes Highway 1 just after Castle Junction due to a collision involving up to five semi trucks. According to 511 Alberta motorists should “expect delays (from) Banff to Lake Louise.”

The type of precipitation that any area receives will be determined by the atmospheric temperature profile that moisture falls through, as well as the temperature of the surface that moisture lands on. Generally speaking higher elevations will correspond to colder air and surface temperatures– meaning moisture in the mountains often remains frozen.

During warmer trends, that moisture can turn into “super-cooled water droplets” and land and freeze on contact with colder mountain surfaces.  

During the day Tuesday, westerly winds will continue to boost temperatures throughout southern Alberta. Winds in Calgary are expected to hover around 20 km/h with stronger winds forecast for the southwest corner of the province.

Highways conditions west of Calgary may become icy again overnight Tuesday with snow and mixed precipitation expected into the mountain parks.

Forecast models suggest snow (purple and white) and mixed precipitation (pink) is expected to fall in the mountain parks early Wednesday.

A broad ridge of high pressure extending from Colorado to the southern Prairies will continue to draw warmer air into the region, and Calgary will continue to see warm and windy conditions for the next few days.

Late Friday this ridge will break down and be replaced by cold, Artic air as a pattern reversal drops temperatures back down to seasonal ranges.

For the latest weather warnings from Environment and Climate Change Canada click here. Driving conditions in Alberta can be found here from 511 Alberta, or here from Drive BC.