Southern Ontario tornado outbreak of 2005

Edit links
Source: Wikipedia, the free encyclopedia.

Southern Ontario Tornado Outbreak of 2005
Supercell thunderstorm hitting Toronto and the surrounding suburbs
TypeTornado outbreak
DurationAugust 19, 2005
Tornadoes
confirmed		3 confirmed, 1 unconfirmed
Max. rating1F2 tornado
Duration of
tornado outbreak2		3 hours, 10 minutes
FatalitiesNone
Damagein excess of $500 million CAD
Areas affectedSouthern Ontario
1Most severe tornado damage; see Fujita scale
2Time from first tornado to last tornado

The Southern Ontario tornado outbreak of 2005 was a series of thunderstorms on the afternoon of August 19, 2005, that spawned tornadoes damaging homes in the

1998 ice storm and the second largest loss event in Canadian history[1] until another event of torrential rain of July 8, 2013 (1 billion CAD).[2]

Meteorological events

Composite weather map on the morning of August 19, 2005
Tornadoes and downpour cells tracks with time shown in local time and their motion speed in yellow

On the early morning of August 19, a low-pressure area was sitting over Northern

jet-stream. All of these were very favorable for the development of severe thunderstorms. Furthermore, the wind shear in the lower troposphere was creating a large helicity value conducive to a tornado potential.[3]

With the advancing cold front, two lines of thunderstorms developed. The first one was near Stratford, Ontario (20 km (12 mi) west of Kitchener), and spread as far north as Georgian Bay near Collingwood, Ontario while the second one was following behind near the shores of Lake Huron.[3] They tracked eastward and reached as far as Oshawa during the afternoon.[1] Dozens of storm cells populated the line, two of them developing into tornadic supercells. At their worst, the tornadoes reached the F2 level, with gusts between 180 and 250 km/h (110 and 160 mph).[1] Severe thunderstorm warnings were sent, mentioning the possibility of tornadoes in view of the radar output and the potential analysis.[3]

The main storm, later dubbed the Toronto Supercell, spawned a first tornado tracking through

Salem (43°41′36″N 80°26′49″W / 43.69333°N 80.44694°W / 43.69333; -80.44694 (Salem)) to Lake Belwood (43°46′05″N 80°20′08″W / 43.76806°N 80.33556°W / 43.76806; -80.33556 (Lake Belwood)) (north of Guelph), passing just to the north of Fergus 10 minutes later.[1] When the storm came close to the Greater Toronto Area, a tornado warning was issued, but the storm changed its characteristics. It produced winds of well over 100 km/h (62 mph), golf ball sized hail, but mostly heavy rain flooding many parts of the city between 2 and 4 pm.[1]

Finally, another severe storm passing Southeast of

Tavistock area (43°12′45″N 80°50′51″W / 43.21250°N 80.84750°W / 43.21250; -80.84750), gave an F1 tornado with winds between 120 and 150 kilometres per hour (75 and 93 mph) by 3:20 pm.[4]

Storm's characteristics

The Toronto Supercell maintained all the characteristics of a tornado producer as it approached the city. Convective storm detection showed on weather radars a hook echo, a BWER and a strong mesocyclone but the vortex left the ground after the second tornado.[3] Studies were made to try to explain the change in behavior to an extremely high producer of rain. One area of Thornhill, just north of the Toronto City limits recorded 175 millimetres (7 in) of rain in less than one hour.[1][3]

Toronto is situated by

temperature inversion which could have been enough to keep the rotation aloft.[3] To the west of the city, there is the Niagara Escarpment, reaching 1,500 feet (460 m) above sea level (ASL), while the shores of Lake Ontario are just 250 feet (76 m) ASL. This drop could equally have cut off the rotation from the surface.[3]

The lightning shows that there was a strong peak during the F2 tornadoes, dominated by the positive cloud-to-ground strikes. Studies have shown that this is often the case in tornadic storms. It was followed by a sharp drop and then another peak, but this one dominated by negative lightning during the flooding phase of the storm.[3]

Impacts

Flood waters washed away a portion of a parking lot near Keele St. and Highway 7 in Vaughan.

The twisters uprooted hundreds of trees, chewed the limbs off of countless others, downed power lines, tossed cars and trucks aside, and ripped into several homes, cottages and barns.[1] In Guelph and Orangeville, 10,000 residents were left without power.[5] No deaths or injuries were reported.[1]

In Toronto, 103 mm (4.1 in) of rain fell in one hour in

Environment Canada.[5]

The rain washed out a portion of Finch Avenue near Sentinel Ave in North York. It overflowed storm drains which caused severe basement flooding to many thousands of homes and two floors of the MSC building. Around Toronto, torrential rains snarled traffic and stranded drivers. Fire services responded to more than 1,000 calls. Marine services personnel rescued four people who fell into the fast-moving currents of the Don River.[1]

See also

References

  1. ^
    Environment Canada. Archived
    from the original on June 11, 2011. Retrieved June 13, 2010.
  2. Environment Canada. Archived
    from the original on December 23, 2015. Retrieved December 21, 2015.
  3. ^ a b c d e f g h Collaborative Science, Technology & Applied Research Program. "The Southern Ontario Severe Weather Event of Aug 19, 2005". State University of New York at Albany. Archived from the original on February 17, 2016. Retrieved June 15, 2010.
  4. Environment Canada. Archived from the original
    on September 28, 2011. Retrieved June 18, 2010.
  5. ^
    CTV News Channel (August 19, 2005). "Ontario endures severe storms, tornado warnings". CTV. Archived from the original
    on April 27, 2006. Retrieved June 16, 2010.

External links
Wikimedia Commons has media related to Severe thunderstorms of 2005-08-19 in Ontario.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Southern_Ontario_tornado_outbreak_of_2005&oldid=1172390076"