Hamilton, Ontario tornado of 2005

The Hamilton, Ontario tornado of 2005 was a tornado that touched down during the late afternoon hours of November 9, 2005 in the city of Hamilton, Ontario.

ynoptic conditions

The first week of November that year had been unusually mild with the jet stream much further north than usual. On the morning of the November 9, a major autumn storm system was passing through northern Ontario (where heavy amounts of snow fell) with much milder air working in across the lower Great Lakes. As the system began to occlude, southern Ontario was forecast to be in the "triple point", a favourable area for the development of severe thunderstorms due to high helicity values. Numerical models (especially the ETA model) had been predicting values of this, in excess of 600–800m^2/s^2 for the risk area.

Along the warm front, some thunderstorms with rotation did develop towards the noon hour along the shores of Lake Erie but this convection was highly elevated and no tornadoes were reported. Later in the afternoon around 3:20 pm, as the cold front approached from the west, a line of fast-moving thunderstorms developed rapidly in the Brantford area. Gusty winds and very heavy downpours were reported by 3:45 pm as they began to move into the west end of Hamilton.

The tornado

, the area of worst damage was concentrated in the subdivisions just east of the Limeridge Shopping Centre. Berko Avenue was particularly hard hit, including Lawfield Elementary School. At that time the damage path was approximately 150 metres wide. The school had the north part of its roof peeled off and the north wall had buckled underneath. Large dumpsters in the school's parking lot were thrown 25 metres. Homes just across the street from Lawfield also sustained serious damage, with some of their roofs almost completely removed and trees snapped or uprooted. Just east of this area there was extensive damage to trees to Bobby Kerr Park but the tornado started to weaken (and probably lifted) shortly after this. There was some weaker damage to a warehouse near the QEW on Millen Avenue but this damage was minor by comparison, and much more intermittent.

with maximum winds of 117–181 km/h (72–113 mph). A tornado track map is provided at right. It is possible that this tornado may have briefly reached F2 strength. One home on Berko Avenue had its roof completely removed, and a neighbouring one had about 90% missing. A nearby evergreen tree about a metre in diameter was uprooted. While this suggests F2 damage, it was also very localized and confined to the small swath along Berko Avenue. The numbers on the map are keyed to damage locations:

# GRAND OAKS DRIVE: Home partially unroofed (F1)
# BELLINGHAM DRIVE: Peeling of roof shingles (F0)
# BERKO AVENUE: Home partially unroofed, snapped tree (F1)
# VERN AMES PUBLIC SCHOOL: Some roof peeling, dumpsters tossed 25 metres (F1)
# BERKO AVENUE: Most of roof removed from home (F1-F2?)
# LAWFIELD PUBLIC SCHOOL: Partial unroofing, buckling of north wall (F1)
# BERKO AVENUE: Home completely unroofed, large evergreen tree uprooted (F2?)
# FIELDING CRESCENT: Wooden fences blown down (F0)
# SHAMROCK COURT: Home partially unroofed (F1)

Climatological rarity

Southern Ontario usually receives about a dozen tornadoes each year, with most of them occurring between May and September. April and October tornadoes are much less common but have occurred on occasion. Tornadoes very rarely occur outside of those time frames. This November 9 tornado was the latest one recorded in Ontario since an F2 tornado hit near Exeter on December 12, 1946. The only other tornado this late in the season was near Leamington on November 29, 1919.

References

*Rennison, John. "Blown Away"." Hamilton Spectator: Nov 10, 2005. A7
* [http://www.ctv.ca/servlet/ArticleNews/story/CTVNews/20051110/hamilton_tornado_claims_051110/20051110?hub=CTVNewsAt11 CTV.ca: Hamilton Hit by Tornado]
* [http://www.ontariostorms.com/2005/index.html OntarioStorms.com: Storms of 2005]