Thursday, September 12th 2019, 1:15 pm - When the warmest and coldest spots in the country get too close for comfort
There are many places in Canada where we might joke about seeing all four seasons in just one day, but how about the hottest and coldest spots in the country landing in one province?
Within 200 km of one another?
Strange but true, that's just what happened last weekend in the Yukon, where one station soared to a high in the mid-20s -- securing the title for warmest spot in the country -- while another dropped below the freezing mark overnight and claimed the title for the coldest.
The players in this hot-and-cold story are Carmacks, a village along the Yukon River, and Burwash, its neighbour 171 km to the west, which sits along the Alaska Highway. On September 8, Carmacks hit an afternoon high of 24.3ºC, while Burwash recorded an early morning low of -4.2ºC.
24 degrees might not sound too impressive for being the hottest temperature in the country for the day, but the pattern for early September comes into play there. A lot of the country trended below seasonal for the first 10 days of the month (indicated by the blue and green-shaded areas on the map below). B.C. and the Yukon were the home for much of the country's heat during that stretch, and the Yukon's sunny skies helped nudge Carmacks to the top of the podium.
Image courtesy WeatherBell.
Those same sunny skies and dry conditions would have also helped temperatures make a big plunge for the overnight hours. Clear skies are poor insulators compared to cloudy ones, allowing a lot of the day's heat to radiate back to space after sunset.
Low humidity contributes to that as well. Temperatures can only drop as far as the dewpoint (i.e. the temperature will never be colder than the dewpoint), and while the dewpoint itself may drop a few degrees after dark, it doesn't change as dramatically as the temperature, since it reflects the amount of moisture in the air. Typically you need an air mass change to significantly change the dewpoint which, for Burwash, was sitting around -6º overnight this weekend. All that combines to mean some chilly, dry nights over the southwestern Yukon.
FROM THE MET DESK: HOW DOES HUMIDITY WORK?
So why such a big difference between the two places? Ah, that's where stats like these can be tricky. While Carmacks took the title for warmest, the high in Burwash on the 8th wasn't all that far behind at 19.5ºC. And the reverse is true, too; on the day Carmacks went on to be warmest, they had an overnight low of -0.5ºC. This makes sense given that both spots are in generally similar terrain, and under the same ridge of high pressure.