Before I get to the updated post I would like to remind my readers that you can also follow my comments on the current and long range weather through my Twitter account @BrettAWX. Twitter allows me to quickly post comments on changing weather situations when my time is short, so check it out.
The Arctic cold front is now (late Monday evening) pressing southeastward across NY,PA and OH taking the brief period of frontal snowfall with it.
The combination of initial rain, followed by some snow and steadily dropping temperatures has resulted in some slick roadways across Ontario and Quebec this evening.
At this time, the lake effect snow is still trying to organize off Georgian Bay and Lake Huron, but I expect a narrow, but potent lake effect snow squall band to move into the London, Ontario area overnight before shifting west and southwest of the city before sunrise.
The graphic below shows the predicted movement of three primary lake-effect snow areas through Tuesday.
Since this band will be shifting a little more quickly than earlier thought I believe most snowfall amounts off Huron will be 15 cm or less, but of course there will be some isolated locations that may see more.
This southern Lake Huron band will weaken later in the morning Tuesday and may actually move back eastward toward London early in the afternoon before breaking up.
A second Lake Huron band may get organized just north of the Hanover region late in the afternoon Tuesday and this band should shift south and southwest later in the evening. Snowfall amounts under that band will likely be in the 10 cm or less range. But as is always the case, trying to predict snowfall amounts for specific areas under these narrow, shifting bands of snow is incredibly challenging.
A third, small band of snow off Georgian Bay will stretch from the Blue Mountains/Wasaga Beach area and extend southeast overnight tonight/early Tuesday perhaps as far as the Newmarket area, but this particular band will be weak compared to the Huron band and thus snowfall will average mostly under 8 cm for most areas, with the highest amounts closer to Georgian Bay and amounts closer to 2-5 cm from New Tecumseth to Newmarket.
Expect some snow showers and flurries for Toronto proper Tuesday morning.
Some needed rainfall for southern Ontario this week.
Mild air masses likely to outnumber the chilly air masses for a good part of October.
Jet stream pattern across North America will become amplified across North America into next week, which means more extremes in weather.
Warm weather will dominate in the eastern half of the country for the next week. Pattern change possible during the last week of September.
The jet stream will strengthen from the Pacific across southern Canada over the next 1-2 weeks which will keep any sustained chilly/cold air masses up across western Alaska and eastern Siberia.
The latest clues to the long range into the month of October.