Friday, 21 December 2012

2012 Severe Thunderstorm Season Across Canada

     First off, this is a yearly post related to the Manitoba thunderstorm season summary which I posted early in the Fall here. Similarly, I have been keeping stats on the Canada severe thunderstorm season since 2010.
     Now in this particular post, I will summarize the SEVERE thunderstorm season across Canada. The stats I gather are of severe thunderstorm warnings and tornado warnings issued by Environment Canada. Everytime a warning of such sort is issued, I note down the day and place and gather all the stats at the end of the year. In addition, I also note all probable and confirmed tornadoes that actually touched down. There is a margin of error however. Sometimes, Environment Canada does make mistakes with issuing severe thunderstorm warnings. Some storms may actually be severe but have no warning on them; also the inverse sometimes occurs (a storm has a warning on it but never actually reached severe limits). However, there is nothing else I can personally do to eliminate this potential margin of error. Therefore, I content myself with just the warnings that EC does issue.
     Let's start with the length of the severe thunderstorm season per province in 2012, from west to east:

     The season began abnormally early in 2012 for the country as Ontario had their first bout of severe storms in mid March, 3 to 4 weeks earlier than in 2010 and 2011. Severe thunderstorms moved through the province on March 15, 17 and 18. Remarkably, even northern Ontario had severe thunderstorms on March 18. Tornado watches were even issued on March 15 in southwestern Ontario, due to the fact some tornadoes had touched down in Michigan. The exceptional warmth and humidity thanks to a jet stream that was much further north than usual was likely the culprit.

     The season was also longer in Saskatchewan and Alberta than it was in 2010 and 2011, starting a couple weeks earlier and ending a couple weeks later. 2012 also was Prince-Edward-Island's first severe thunderstorm in at least 3 years (there was none in 2010 and 2011).

     Now, as for the frequency of severe thunderstorm warnings per region in Canada in 2012, I have made a map for you all to make it easier to visualize which areas were most active:

     (Unfortunately, the way I have divided the country on this map is not perfect since the regions are not of equal size. I do plan to fix this problem in 2013.)

     With this map, it is easy to point out the most active regions; the western Prairies, northwestern Ontario and southeastern Québec. There are also other anomalies to point out however. Parts of southern Ontario were quieter than in the past 2 years, while BC was much more active. In fact, BC tripled the number of severe days seen in 2011 and saw 5 times more than in 2010.

     The biggest highlight however was the western Prairies. An unusually humid summer combined with a jet stream that was further north than usual brought frequent severe weather to Saskatchewan and Alberta. In Alberta, there was an amazing 54 days of severe thunderstorms throughout the year, 20-25 days more than in both 2010 and 2011.

     According to Environment Canada, it was the second busiest summer for severe thunderstorms in the Prairies since they've been keeping records in 1991. There were 371 severe thunderstorm events across the 3 Prairie provinces; Alberta saw a record number of 169 events while Saskatchewan saw its second highest number with 135 events. Of the 63 days between June 13 and August 14 only 11 days were free of severe weather.
     This year was also the second worst on record for hailstorms in the Prairies. In Alberta, it was a record year for crop losses. As for windstorms, it was also the second worst in the Prairies with 81 events of gusts of over 90 km/h. Again in Alberta, it was the worst year for windstorms with 41  events, breaking the old record of 37 events in 2007.
     Almost daily severe thunderstorms in Alberta in July brought serious flooding to some areas. The Edmonton region saw record rainfall for July. Stony Plain, a suburb west of Edmonton, received a total of 247.3 mm, the wettest July on record.

     Now, here's another map; this one showing the frequency of tornado warnings per region in Canada in 2012.

     Alberta and in particular Saskatchewan, saw numerous tornado warning events this season. Meanwhile, it was abnormally quiet for tornadoes in Manitoba and southwestern Ontario. Just 3 weak tornadoes were reported to Environment Canada in Manitoba, keeping in mind that none of these were actually confirmed. Saskatchewan however saw 33 tornado touchdowns, the highest amount ever in a single year for the province. Normally, Saskatchewan only sees about 13 tornadoes.

     Below is my last map; this one shows where all the probable and confirmed tornadoes occurred in Canada this season. This likely is an incomplete list; I don't have access to Environment Canada tornado reports. I use twitter, and media sources such as CTV, CBC and The weather network  for this data.

Inuvik, NWT tornado Jul 28
     The strongest confirmed tornado this season was an F2 near Storms Corner, Ontario on September 8. Unfortunately, Environment Canada has not, to my knowledge, rated all the tornadoes in western Canada. Only one F1 near Olds, Alberta on July 3 was confirmed.

     Notice that a tornado touched down all the way up near Inuvik, NWT. This occurred on July 28, and was certainly a surprise to those who saw it. Although it may seem unusual, tornadoes in NWT are not actually that rare. We just never hear about them, because most of the time no one ever sees them due to the low population density in the area. The strongest known tornado in the territory was an F2 wedge tornado in Yellowknife in 1978.

     The latest confirmed twister this year was a minor F0 near Mont-Laurier, Québec in the afternoon of October 31. It was one of the latest confirmed tornadoes on record. Some later confirmed tornadoes since the 1800's include: Nov 9, 2005 (Hamilton), Nov 16, 1989 (F2 near Mont-Saint-Hilaire, Québec), and Nov 1950 (Regina).

     And now to finish off, here's some links to some information on notable severe storm events this year:

1 - June 5/6 supercells in Alberta
2 - June 25 to 27 wicked thunderstorms in Saskatchewan
3 - Greg Johnson's collection of storm pictures 2012
4 - August 12 Calgary hailstorms
5 - July 23 eastern Ontario severe storms
6 - Hours of thunderstorms flood the Thunder Bay area in late May
7 - Montreal flooded after drenching thunderstorm May 29
8 - Heavy thunderstorms flood Edmonton early July 12

Some sources of the pictures and information I provided in this post:
The Weather Network
Environment Canada's Top 10 weather events of 2012

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