Cedar Valley to Vivian, ON F1 Tornado of July 17, 2006

York - Durham

This second tornado in the Newmarket area was 100 metres wide and tracked for 9 kilometres. Trees were snapped and uprooted and damage occurred at a factory; part of its roof was removed and a heavy steel shipping container in the yard was moved and deposited on a stack of irrigation pipes.

Figure 1 depicts the surface observations at 8:00 pm EDT, which shows a cold front slicing through the Great Lakes. Pre-frontal storms developed in southern Ontario in the form of a cluster of storms (Figure 2), which ultimately led to two tornadoes in Newmarket and Cedar Valley.

Figure 1. Surface analysis at 00Z on July 18, 2006 showing mean sea-level pressure (MSLP) contours, surface observations, fronts and pressure centres (WPC, 2017)

Figure 2 shows the Doppler radar reflectivity at 10:10 pm moments before the tornadoes developed near Newmarket.

Figure 2. Doppler radar imagery at 10:10 pm EDT on July 17, 2006 (Source: Meteologix)

According to Environment and Climate Change Canada (2018), an F1 tornado touched down at 10:15 pm near Cedar Valley, ON. The tornado travelled for 8.84 km with a maximum width of 100 metres. The tornado caused no fatalities, injuries or property damage.


NWS Weather Prediction Center Surface Analysis Archive. (2017). Surface analysis 00Z Tue Jul 18 2006. Retrieved from: https://www.wpc.ncep.noaa.gov/archives/web_pages/sfc/sfc_archive.php

Environment and Climate Change Canada Data. (2018). Canadian National Tornado Database: Verified Events (1980-2009) – Public. Retrieved from: http://donnees.ec.gc.ca/data/weather/products/canadian-national-tornado-database-verified-events-1980-2009-public/