A short, but moderate-sized lake-effect snow event will set up tonight (Friday) and tomorrow (Saturday) downwind of the Great Lakes as gusty winds spread much colder air over the relatively warmer Great Lakes.
I have narrowed down the areas where I think there is a greater potential for over 10 cm of snow as we are more confident with the wind flow. Since yesterday, it appears that the primary wind direction will not be NNW to SSE, but more of a true NW to SE flow.
With this slight adjustment, it looks like the primary snow band off Lake Huron will end up just north and east of the London, Ontario, area. This band may eventually get all the way down into parts of north-central Pennsylvania by Saturday afternoon before weakening. Under this band, a few locations well to the north and northeast of London, Ontario, could end up with locally 20 cm or more.
There should also be a shorter, weaker band off Georgian Bay.
Under these bands visibility will quickly get reduced and roads will get covered quickly.
The Huron band should slowly shift toward the south midday Saturday before weakening late in the day.
By the way.....
Looking more an more likely that the two branches of the jet stream will not phase early next week, which will prevent a storm from moving up into Ontario on Tuesday, though it will end up being colder with some flurries.
Large storm clashing with warmth and higher humidity will lead to heavy rainfall and locally severe thunderstorms over the Prairies the next couple of days.
Potential for localized rainfall amounts in excess of 100 mm (4 inches) over western Alberta this week....
Here is my latest interpretation of the ECMWF weekly update that goes into mid-July.....
Potential for strong thunderstorms and heavy rainfall Wednesday/Wednesday night.
What the latest ECMWF seasonal forecast output shows for July, August and September...
Below is my interpretation of last night's release of the latest ECMWF model weeklies that now go out through the first week of July.