While residents of Alberta and Saskatchewan are being greeted by blowing snow and biting wind-chills this morning, those living in Ontario and Quebec are enjoying a mid-winter thaw this week, both due to the same winter storm.
From Calgary towards Regina, wind gusts of 60-90 km/h are whipping up freshly-fallen snow, cutting visibility down to less than 1 km, and driving wind chills down to near -40. These winds should die down for Alberta this afternoon, but with the Colorado Low that's kicking up these winds passing by to the southeast, on its way towards the Great Lakes, these conditions will likely keep moving along with it, impacting on the rest of southern Saskatchewan and Manitoba before the storm passes completely.
[ Related: Freezing rain to hit Ottawa this afternoon ]
With the wind chill that low, it's not just uncomfortable, it's actually dangerous. Skin exposed to that combination of freezing temperatures and driving winds can lose heat so fast that it can actually freeze in less than 10 minutes. Add water to the equation, by sweating or getting your skin wet with melting snow, and that time can drop significantly! The resulting frostbite is due to the water in your skin cells expanding as it freezes, and actually bursting the cells. Infection can set in if it isn't treated quickly, and you can lose fingers or toes (or worse) due to this.
By contrast, southern Ontario is having relatively balmy, if dreary weather today. Afternoon highs range from 14 degrees in Windsor to 5 degrees in Toronto, with progressively cooler weather as you move further east. These warmer temperatures will move into eastern Ontario and southern Quebec tomorrow, allowing people living along the lower Great Lakes and St. Lawrence Valley to shed the layers for at least a couple of days before it gets colder again on Thursday.
This Colorado Low storm is a classic weather system for meteorologists.
The warm front from this system is currently giving the St. Lawrence Valley the same treatment it delivered to the lower Great Lakes from Sunday night through until this morning. Snow, followed by freezing rain along the front, and all switching to rain as the front passes. The balmy temperatures in the 'warm sector' of the system are due to warm, humid winds being sucked from the U.S. Southeast into the low pressure at the centre of the storm, and these warm winds are supplying most of the energy (and all the precipitation) to the weather system.
The same cold winds being swirled around the northwest and west sides of the low pressure, which are causing the blowing snow and wind chills in the prairies, are driving a cold front ahead of them. As this front tracks past the Lakes and into Quebec starting on Thursday, it will drive the warmer temperatures ahead of it, leaving behind more chilly, snowy weather for the weekend and probably much of next week as well.
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