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This is a damage survey conducted by Laura Duchesne and Bob Berry. Bob took these photos and are used with permission. This report was sent to the Ontario Storm Prediction Centre and remains unconfirmed.

WIND DAMAGE IN THAMESFORD

Prepared by: Laura Duchesne, Bob Berry

Date of Event: May 22, 2004

Time of Event: Between 18:00 & 18:30 EDT

Location affected: Town of Thamesford (~10km WNW of Ingersoll, Ontario)

Date & Time of Survey: May 23, 2004 16:00hrs

Background:

Severe thunderstorms roared through southwestern Ontario on the evening of Saturday May 22, 2004. Two confirmed tornadoes struck the communities of Gads Hill (F3) and Mitchell (F2). The town of Thamesford was also struck by a strong wind event that night. It is unclear as to what happened here was a tornado or not. There are elements of tornado damage and microburst-like damage.

Collected Data:

Two young women at a Mac's Milk store were direct witnesses to the events during which the damage occurred. They told us it was calm before the heavy rain hit. It gradually got heavier until the two could not see the houses across the street (which were no more than 40-50 feet away). One said there were many cars parked on the side of the road because the rain was so intense (motorists couldn't see anything). There was a surge in wind and within a few seconds, trees were thrashing violently and things started to fly through the air. There were 10 other people who sought shelter in the store due to the blinding rain and they watched the storm approach through the large-paned glass windows in the front of the store (just before the winds hit)! One witness described the debris as swirling through the air, the same witness also saw a “swirling” in the sky. Witnesses said storm occurred between 6 and 6:30 pm. Within 15 seconds the winds were gone, but not before damaging the store, a fruit/vegetable stand, a garage, and one or two other outbuildings in the town. Two other people that lived in the house to the west of the Mac’s store (house with wooden fence in one picture) also confirmed the time, duration and intensity of the rain and winds, although they did not see any "swirling" debris (from their vantage point) when asked. In total, 4 witnesses were interviewed about the previous days events.

A vegetable/fruit stand sitting in a field across the street west of the Mac's Milk store was demolished. A steel support bar from the frame of the fruit stand and other miscellaneous debris hit the roof of the Mac's milk store damaging it. The bar pierced the roof causing a 1/2 foot x 1 foot gaping hole in it. The roofing material was constructed of a heavy plywood, and visually, it appears as though an impression with the approximate width of one of the steel bars was stamped into the aluminum siding. There was also 1/4" thick steel cabling (part of the tie-down support for the fruit/vegetable tent) completely wrapped around the tables that were being used at the time to display the produce. The ladies from the Mac's store could not unwind it from the tangled and crumpled mess that resulted.

Witness said that an old lady was walking her dog during the tempest and a piece of debris from the fruit stand hit her, causing her to fall. She was not injured except for the scare she received from the storm. She sought shelter at the other corner of the store (the same side that received the roof damage) near the dumpster (bad place to have been)!

There was a large open field where the top portion of several trees were snapped or stripped of foliage. Bark was shredded and scattered about the property, with many branches and other debris, (including broken plastic pieces from the tent and its associated equipment). Two twigs were found impaled into the ground no more than 1-2 inches deep without far away from any of the trees or any other larger limbs/branches. Most of the branches seemed to be facing in the same direction, but there were a few that were facing in a different direction. Several people were asked if anyone had been by to cleanup the property but no one could really say one way or the other. It did appear though that there was some cleanup that was performed as some of the larger fallen branches were lined along hwy 2, either that, or the limbs/branches did not carry very far from where they came. It appears the damage followed a northwest to southeasterly path through the town. A number of limbs felled were about 1 foot diameter thick and smaller. Branches and leaves were blown in every direction as far as across the street toward the Mac's store, which was well away from the line of trees to the WSW (at least 250-300 ft. or more).

Among other items found damaged were a ¾ inch thick wooden zorra township sign, which was split in half (the other half of which could not be found). Damage to an adjacent garage next to the milk store (to the S) was also evident and several windows on the north side were blown out. There was also a report of a shed or garage that got lifted and moved off its foundation (SE of the location of the mac's store about a km away) within the town limits. This report was not investigated.

Facing SSE on the E side of the Mac’s Milk parking lot.

Looking due East at the Mac’s Milk store. Note the hole caused by supporting leg from tent. Also evident are pieces of wood from the stand as well as the tarp covering the tent. Soffit area also had a hole torn into it.

Below shows a close-up of the roof damage. Note the pockmarks and impressions elsewhere on the siding where debris impacted it and also the impressed diagonal line leading up to the hole in the roof and to the soffit area underneath.

Facing SW at the remains of the fruit/vegetable stand. Behind the corner of the farthest piece of fence, there were a few tree limbs snapped off as well (estimated distance: 400-500 ft). Some of the deciduous trees in the background also had a few limbs felled.

Close-up of the furniture used under the fruit tent. The punctured white table was constructed of a thick plastic material. Note the 1/4 " thick steel reinforcement cable wrapped around the mess.

Picture facing SE (Mac's store west wall is to the left of the picture). Garage of house in the line of sight sustained some damage mainly in the form of blown out windows throughout and a little roof damage.

Laura holds up a Zorra township sign that was split in half.

Looking due WSW along Rd. 86 (old Hwy 2). Large limbs are down from the stand of trees lining the highway. Also note the conifer (left center) with its top stripped of foliage. Also strange is the way the rather hollow limb broke off from its (2nd tree from the right in the stand) parent, coming to rest against its neighbour.

Here is a close-up of some of the felled limbs. Limbs shown here on the ground are facing due east. Also note the hollow limb and where it broke off, coming to rest on its neighbour.

Facing NW. Branches from a few trees across the street came to rest here on the hydro pole. Note small conifer in across the street (just to the right of the pole) snapped off at the base and pointing in a SE direction.

Twig embedded into the grass (evident from the darker soil-covered portion). The depth of penetration was very close to 2 inches.

Looking NE: Mac's milk sign damaged from flying debris.

A map of the damage scene in Thamesford.

Conclusion:

Given the evidence gathered in the time allotted, there is not enough evidence to conclusively prove tornado only or microburst only. The arguments supporting tornado include: all of the damage affected a very small region, damage was clearly defined from non-damaged areas, the damage seemed spotty along the track (for instance, large tree limbs or entire trees snapped off, but no damage to an adjacent fencing system and house), eyewitness reports of swirling in the clouds. Arguments against tornado: a lot of the damage is facing one direction or was not moved very far from its original location (ie: tree limbs), no mud splatter and or leaves was evident on walls, and no supporting video/camera evidence. Radar captures or sequences from that day and time could possibly help to further the understanding of what went on here.