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Isolated Severe Thunderstorms in Southern Ontario; 2-3cm Hail, 100km/h Winds, Isolated Tornado

Thunderstorm Forecast, for Southern Ontario. Issued June 28th, 2019.
Thunderstorm Forecast, for Southern Ontario. Issued June 28th, 2019.

We are currently watching the risk for some isolated severe thunderstorms across portions of Central and Eastern Ontario and some more scattered severe thunderstorms across Southwestern Ontario.


Showers and thunderstorms are expected to cross the region throughout the late morning/early afternoon hours in Southern Ontario. Between 12 and 2pm, showers and thunderstorms will cross from west to east in a line which extends from North Bay towards Sarnia. The showers and thunderstorms will reach the GTA and Ottawa regions between 1 and 4pm.

Some of the thunderstorms look rather strong in the model data for portions of the Ottawa Valley extending from Ottawa through towards Peterborough and Belleville. An isolated severe thunderstorm can't be ruled out with these storms.

Into the late afternoon and early evening hours, showers and thunderstorms are likely to continue east into New York State as well as linger across Central and Eastern Ontario. Scattered showers are likely.

*IF* the morning showers clear in time to allow for daytime heating in the afternoon, than, across Southwestern Ontario, scattered showers and thunderstorms are likely to redevelop from an area expanding from Kincardine and Amberley towards Kitchener and Guelph towards Chatham and London, including everything in between. Some of these thunderstorms have the risk of being severe. The main threats with these thunderstorms are rainfall totals over 50mm, moderate to large sized hail between 1.5 and 3cm and gusty winds between 80 and 100km/h, locally higher are possible.

These redeveloped thunderstorms will move east again towards the Niagara and GTA regions. Some of these thunderstorms may remain severe. The main threats in these regions are rainfall totals over 50mm and moderate sized hail between 1.5 and 2cm. Gusty winds are also possible towards 90km/h.

In the 'area of interest,' we can't rule out the risk of an isolated tornado or two.


Areas highlighted in blue or marked with a '1' have a risk for mainly non-severe storms.

Areas highlighted in green or marked with a '2' have a low risk for severe storms.

Areas highlighted in yellow or marked with a '3' have a moderate risk for severe storms.


We will be watching.

Any updates needed to the forecast will be posted here below.


There are no updates at this time.

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