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2013 summer winners and losers: Summer shows late-season strength

Photo: Yolanda Wittmeier

Photo: Yolanda Wittmeier


Chris Scott
Chief Meteorologist

Tuesday, August 20, 2013, 1:46 PM -

The weather pattern through month’s end is looking more like mid-summer than the end of August.  While there will be some spells of cooler weather in parts of southern Canada to round out climatological summer (the months of June, July and August), the season will be making a strong finish across much of the country.

Who’s been up - Who’s been down

The picture below shows areas of North America which have been warmer than normal (green-yellow-orange shading) vs cooler than normal (blue shading) from the beginning of June through August 18. B.C. has had a warm summer as has much of Atlantic Canada.  However, the biggest departure from normal has been near the Arctic Circle, where locations like Kugluktuk saw 9 days in a row with temperatures above 27 C, and even eclipsed 30 C for the first time ever in August (the average daily high is only 13 C).  

The losers have been areas from southern Manitoba through northern and southern Ontario -- but not by a large margin when considering that the average temperature is running less than a degree below normal.  However, there have been some rather cool stretches of weather in these areas, and some less than beach friendly days at times during the peak vacation period.

Temperature departures from normal across North America from June 1 - August 18. Blue shading indicates below normal while green-yellow-orange shading indicates above normal temperatures.

Temperature departures from normal across North America from June 1 - August 18. Blue shading indicates below normal while green-yellow-orange shading indicates above normal temperatures.

What’s to come

The weather pattern for the remainder of August is trying its best to level the playing field as mid-summer heat will remained anchored across the central and western U.S. for the next 10 days. Some of this heat will bleed across the border and give stretches of warmer than normal weather across the Prairies and into Ontario.  Cool shots of air will nip away at this heat periodically, but overall the last half of August will be warmer than the first from Winnipeg to Toronto.

Cold air is showing up on the weather map where we expect it to be – near and north of the Arctic circle. The first snow of the season has been falling across the Arctic Archipelago (where it only really stops for about a month) and the early signs of Autumn are beginning to show up on the weather charts.  However, there are no signs this pool of colder air building in the arctic will make any meaningful headway to the south any time soon.  In fact, this type of weather pattern favours warmer than normal weather across southern Canada as the jet stream tends not to get stuck as easily (like it did in early August).

Computer model forecast of temperatures at 850 mb (about 1.5 km altitude) on Sunday. Note the strong north-south contrast in temperature across Canada as Autumn air begins building across the arctic while surging heat returns to the southern Prairies. Courtesy College of Dupage Weather Lab.

Computer model forecast of temperatures at 850 mb (about 1.5 km altitude) on Sunday. Note the strong north-south contrast in temperature across Canada as Autumn air begins building across the arctic while surging heat returns to the southern Prairies. Courtesy College of Dupage Weather Lab.

Looking beyond into the last week of August and the Labour Day long weekend, this general weather pattern looks to hold sway meaning that much of southern Canada should experience at or above normal temperatures. As we get closer to the long weekend, we’ll have a better idea on the timing of individual low pressure systems which can muck-up this general trend, but at this point the trend is in favour of warmth.

8-14 day temperature outlook. Orange shading indicates greater than 50% chance of above normal temperatures. Courtesy Environment Canada.

8-14 day temperature outlook. Orange shading indicates greater than 50% chance of above normal temperatures. Courtesy Environment Canada.

Storms to watch

With this late summer heat comes the threat of severe thunderstorms.  Over the next few days, the focus will be on a cold front moving across Ontario from north to south, bringing with it the chance of locally powerful storms, particularly Wednesday from Cochrane to Moosonee.  The Prairies, which have been relatively quiet as of late for big storms, should see some more action by this weekend as heat builds in from the U.S.

The Atlantic hurricane season has been a quiet one so far. Although there have been five named storms, generally dry air across the tropical Atlantic coupled with unfavourable jet stream winds are making for a quiet August. However, hurricane activity often occurs in bunches, and it wouldn’t be surprising to see a surge in activity during the climatological peak of the season as we move into September. The current weather pattern is a very protective one for Atlantic Canada. Any storms that would develop in the next two weeks would tend to get steered out to sea – but we’ll be keeping an eye on changes to this jet stream pattern in September for any tropical trouble which could approach.  

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