Forecast of thunderstorm potential.

Today..Isolated non-severe thunderstorms are possible this afternoon
over Northeastern Ontario to the southeast of a line from Sault Ste
Marie to Timmins and Cochrane and over Southern Ontario particularly
near lakes Erie and Ontario. Some of the thunderstorms over Southern
Ontario may approach severe limits this afternoon with wind gusts to
85 km/h, very heavy downpours giving localized rainfall amounts of
20 to 40 mm in under an hour and marble to penny sized hail.

Tonight..Over Northeastern Ontario southeast of a line from sault
Ste Marie to Cochrane isolated non severe thunderstorms are
Possible this evening. Over Southern Ontario a few non-severe
thunderstorms with heavy downpours, hail and gusty winds are
Possible this evening especially near lakes Erie and Ontario. Moving
into Southwestern Ontario overnight in advance of a strengthening
Low pressure area approaching from the us midwest, isolated
non-severe thunderstorms with very heavy downpours are possible.

Saturday..Isolated non-severe thunderstorms with heavy downpours and
gusty winds are possible over southern and Eastern Ontario as a
strong low pressure system moves northeast across the district into
Quebec.

Special weather statement for:
=new= City of Toronto
=new= Windsor - Essex - Chatham-Kent
=new= Sarnia - Lambton
=new= Elgin
=new= London - Middlesex
=new= Simcoe - Delhi - Norfolk
=new= Oxford - Brant
=new= Niagara
=new= City of Hamilton
=new= Halton - Peel
=new= York - Durham
=new= Huron - Perth
=new= Waterloo - Wellington
=new= Dufferin - Innisfil
=new= Grey - Bruce
=new= Barrie - Orillia - Midland
=new= Belleville - Quinte - Northumberland
=new= Kingston - Prince Edward
=new= Peterborough - Kawartha Lakes
=new= Stirling - Tweed - South Frontenac
=new= Bancroft - Bon Echo Park
=new= Brockville - Leeds and Grenville
=new= City of Ottawa
=new= Gatineau
=new= Smiths Falls - Lanark - Sharbot Lake
=new= Parry Sound - Muskoka
=new= Haliburton
=new= Renfrew - Pembroke - Barry's Bay
=new= Algonquin
=new= Burk's Falls - Bayfield Inlet.

Significant rainfall on tap tonight into Saturday.

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==discussion==

A low pressure area over the us midwest is forecast to track
towards the Great Lakes today then intensify as it moves across
Southern Ontario into Quebec on Saturday.

This disturbance will be quite laden with moisture and is
Expected to bring a general 20 to 40 mm rainfall across much of the
district by Saturday evening.

A few local rainfall amounts near 50 mm are possible in areas that
receive a thunderstorm or two.

In the wake of this disturbance later Saturday and into Sunday,
considerably cooler air ushered in by brisk northwesterly winds will
bring a taste of fall to Southern Ontario.

Environment Canada is monitoring this situation closely.

The public is advised to monitor future forecasts and warnings as
warnings may be required or extended.