Watford, ON F2 Tornado of July 23, 2011

Sarnia - Lambton

Blown Apart
Figure 1. Damage to a barn from F2 tornado on July 23, 2011 (Lochem, 2011).

This heavily rain-wrapped F2 tornado first touched down near the intersection of Forest Road and Churchill Line to the east of Wyoming and tracked to south of Watford. Its path was 11 kilometres long and 500 metres wide, travelling through sparsely populated areas of Lambton County.

Trees were snapped and uprooted, barns were destroyed, and six steel Hydro One transmission towers were twisted and toppled, leaving 60,000 people without power and earning the tornado its high-end F2 rating. It dissipated south of Watford.

Figure 2. Doppler radar reflectivity at 7:28 pm EDT (via meteologix.com).

Figure 2 depicts the radar imagery at 7:28 pm, which shows a supercell with a classic ‘hook echo’ just east of Sarnia, ON. This storm was responsible for the strong F2 tornado east of Wyoming on this day.

Figure 3. Surface analysis at 00Z on July 24, 2011 showing mean sea-level pressure (MSLP) contours, surface observations, fronts and pressure centres (WPC, 2017)

Figure 3 shows the surface observations at 8:00 pm EDT, which shows southerly winds across southwestern Ontario. Storms initiated in eastern Michigan and crossed into Ontario in the evening hours.


Lochem, V. (2011). Blow Apart [online]. Retrieved from https://www.flickr.com/photos/37967119@N08/11328821663/in/photolist-ig6aZr-6tY8R-6RsQ5E-fdwTR5-gUa5n-6RrRHk-Jo2MQh-yu7jv5-6tYir-oSWjDg-6Rp8PK-6tXMW-cpbcZ5-8fQ4RX-57X7VX-afuMrY-pahcUy-6tXJL-6tYbn-cBZYjL-jBGsv-6tXMk-6tYgZ-6SiFns-6V4TA5-oSVZz7-oSQyfg-aKgh5i-9SSZkZ-oRau1R-4Ycmeu-9YHnbS-djJWBN-prYnCS-afhNJ6-89nauk-fc1Ri-e916co-o41yt6-afs12k-oSVXE5-pa7aZF-6tXLR-ig8g5T-7vDd93-afuFK9-aftY2x-6tXKq-p8hc77-pajpMa/

NWS Weather Prediction Center Surface Analysis Archive. (2017). Surface analysis 00Z Sun Jul 24 2011. Retrieved from: https://www.wpc.ncep.noaa.gov/archives/web_pages/sfc/sfc_archive.php