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What's in the forecast (and the oven) ahead of Thanksgiving ...


Dr. Doug Gillham
Meteorologist, PhD

Tuesday, October 8, 2013, 7:26 -

While autumn officially runs from September 22 to December 20th, typically when we think about fall weather the months of September, October, and November come to mind. From that perspective, we are approaching the mid-point of the fall weather season, so let’s review what we have seen so far, and take a look ahead to what we can expect during the upcoming Thanksgiving weekend.

While August featured several rounds of autumnal weather over central and eastern Canada, summer made a strong comeback during September from the interior of British Columbia to Western Ontario.  From Kenora to Kamloops, high temperatures averaged two to five degrees above seasonal for the month of September. Saskatoon especially stands out with an average high of 23.8 °C, which is 5.3 °C above their average high of 18.3 °C. 

From Southern Ontario through the Maritimes, a mix of both warm and cool days during September resulted in temperatures that were within a degree of the long term averages for the month. Coastal British Columbia also saw temperatures close to seasonal for the month. However, September was very warm and humid in Newfoundland as the average high of 18.5 °C in St. John’s was two degrees above seasonal. The Avalon Peninsula will also remember September 2013 for several days of unusually high humidity. The second highest dewpoint on record was recorded on September 14 (23.1 °C), which was just shy of the all-time highest dewpoint which was recorded earlier in the summer.  

Rainfall during September was highly variable across the country. Edmonton received only 1.8 mm (average is 40.3 mm) and Saskatoon only received 3.5 mm (average is 34.1 mm). On the other hand, two late-month storms brought Vancouver’s rainfall total to 155.6 mm, which is over triple their average rainfall for September. Atlantic Canada also had a wet September as a couple of slow moving systems with tropical moisture contributed to Charlottetown’s total of 176.4 mm and St. John’s’ total of 211.4 mm, nearly double the two cities’ average rainfall for September. Much of the rest of the country saw rain totals close to their monthly averages.

Outside of Canada, we saw a continuation of two interesting trends into early October. We are over 75 per cent of the way through the Atlantic Hurricane season and with 11 named storms so far, it would appear that we are in the midst of an active season. However, most of the storms have been weak and short-lived. The Accumulated Cyclone Energy (ACE) Index is a better tool for comparing the intensity of tropical seasons and so far 2013 is 71 per cent below normal, making this the fifth least active year since 1950.  

Typically when the Atlantic basin has a quieter season, this is offset by higher than normal tropical cyclone activity in other parts of the world. However, the global ACE Index number is 46% below normal and at its lowest level since 1977. (Source: Dr. Ryan Maue)

In addition, the trend of seeing less severe weather across North America continued through September. Even after the October 4 tornado outbreak in Nebraska, South Dakota and Iowa, the United States has seen fewer tornadoes this year than any other year in modern record keeping history (starting 1950).  The total of 649 through October 4 is well below the previous record low of 761.

During the first week of October, much of Canada saw a reversal in the pattern that dominated much of September with the cooler than seasonal temperatures for B.C. and the Prairies and warmer than seasonal from Ontario to Atlantic Canada. As we look ahead to the Thanksgiving long weekend, it looks like this pattern will continue. There is actually good agreement among the different models for the upcoming weekend though a slow moving storm late in the week off the East Coast of the United States does have the potential to impact the timing of systems across the country.

On Saturday, most of B.C. and the Prairies can expect temperatures that are below seasonal, while warmer than seasonal temperatures are expected for Ontario and Quebec. The Maritimes look to be near-to-below seasonal with rather chilly conditions for Newfoundland. The image below highlights the temperature trends for Saturday across North America according to one of the long range forecast models. The most active weather on Saturday will be in Manitoba, where strong winds and heavy rain are likely.

Little change in this overall pattern is expected for Sunday, though the cool temperatures in the Prairies are expected to move into western Ontario.

For Thanksgiving Day, B.C. and Alberta will see a few degrees of warming while temperatures in Southern Ontario and Quebec will cool a few degrees, but they should still remain above seasonal. For Atlantic Canada, Thanksgiving should be the warmest day of the long weekend.

For more details on the weather in your local area or on how the weather will impact your travel plans, please be sure watch for updates from us on television and at theweathernetwork.com 

For more details on the wild weather that the fall season often brings across Canada, be sure to read meteorologist Rob Davis’ article on fall as a season of extremes.

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