Finally! Summer returns to those it left
Thursday, August 15, 2013, 11:06 AM -
Summer has been missing for certain parts of the country but more than prevalent in other parts. British Columbia and the Territories have been baking in the heat, Atlantic Canada has been seasonal but the eastern Prairies, Ontario and Quebec have been lackluster in terms of summer weather the last couple of weeks.
Why is this? We have been in a blocking pattern across the country which essentially means the weather systems aren’t moving anywhere fast. Depending on where you are within the blocking pattern dictates the type of weather you received. Those on the west coast have been stuck under the “ridge” of the blocking pattern meaning they have had dry, warm weather (with the odd thunderstorm). The eastern Prairies and Ontario and Quebec have been stuck in the “trough” of the blocking pattern. This means cool, unsettled weather which is what has been the story the first couple of weeks of August.
Up until the third week of July, most of the country was experiencing a fairly normal summer when it came to temperatures. The exception would be the Territories where temperatures were above normal. Once we entered the last week of July and into August, the country got trapped in this blocking pattern and temperatures were on the rise in British Columbia but on the decline in the Eastern Prairies right through to Quebec.
The first graphic below shows the mean temperature deviation from normal for the summer so far (up until August 12).
However, we can take a look at the first couple of weeks of August in this second graphic and notice all the cooler-than-normal air that has been trapped over the central portion of the country and all the warmer-than-normal air that has been breaking temperature records in the western Territories. There is no doubt that the last few weeks have been cool in central Canada with the biggest deviation below normal being in Manitoba and northern Ontario. We can attribute the June-August below-normal temperatures to the last week of July and first couple of weeks of August. Taking a look at June and July on their own, the country wasn’t fairing too bad with respect to temperatures.
Taking a look at the climate normals for the first two weeks of August we can see major cities in the central portion of the country are below seasonal. Toronto is normally about 26 - 27°C as daytime highs for the first two weeks of August where this year Toronto has been averaging about 24°C. The beginning of August is when we start to see the overnight lows dip into the low teens. The most drastic major city would be Winnipeg with their first two weeks averaging highs of around 22°C where normally the highs are around 26°C. The overnight lows have been drastic as well averaging to 8°C where normally they are 13°C. The nation’s capital, Ottawa, averages the same as well with the highs and lows below normal for the first two weeks of August. Taking a look at the data for northern Ontario locales and we see the same results.
Looking back at the last five years, most major cities from Manitoba to Quebec have not experienced a below normal August since 2008 or 2009. So in recent memory, the last few years, this is certainly the coolest start to August we have experienced unless you go back to 2008 or 2009.
There’s good news for those who haven’t been enjoying the cool, unsettled weather … Change is here! The pattern is breaking down allowing for warm temperatures to move back into the Prairies, Ontario and Quebec. Temperatures are forecast to be in the high 20’s and low 30’s from Alberta to Manitoba right through the weekend. In Ontario and Quebec, temperatures will warm back up this weekend and for the better part of next week. This pattern change, however, will cause places like British Columbia (especially the coast) and the Territories to experience more seasonal or cooler-than-seasonal temperatures for the next while. This will also allow rainy and unsettled conditions to settle back into the British Columbia coast where July and the beginning of August were warm and dry.
This summer has been getting a bad rap from many folks across the Prairies, Ontario and Quebec and some of it is justified. This summer has held record breaking rainfalls in Alberta and Toronto leading to flooding in both locales. Also, June didn’t start off so hot, pardon the pun, with below seasonal temperatures plaguing eastern Canada. The summer just hasn’t been consistent. Some days were hot, we even had a heatwave in July. Some days were very cool, enough for heavy sweaters. We always compare seasons to the best of our memory and last summer was hot. We set all-time records across the country last summer with the heat and had temperatures climbing to near 40C. We are soon to forget that we already had a heat wave this summer but the recent cool snap in the Eastern Prairies, Ontario and Quebec has skewed our views on this summer. The inconsistency of this summer has left it with a bad reputation of a not-so-pleasant summer.
The summer pattern does not necessarily dictate what the fall will be like. The past few weeks have been a result of a small scale blocking pattern but if we look at the rest of the summer prior to this, temperatures were normal. There is still summer left but one thing to keep in mind is that the overnight temperatures are dropping throughout August so even though the daytimes will be warm, evening and nighttime temperatures will be cool.
The Weather Network will be releasing its Fall Outlook just in time for back-to-school so check back for that at the end of August.