Despite the fact that Ontario will be blessed with beautiful weather this coming weekend, we can expect a series of global weather pattern reversals to bring snowfall and fluctuating temperatures to the province (and soon too).
According to The Weather Network, a pattern reversal occurring next week will bring the coldest weather relative to normal to the Great Lakes, where warmest so far this past month. The resulting conditions will be perfect for the development of lake effect rain and snow in the surrounding areas (i.e., WIndsor, London, Toronto, Sault Ste. Marie, etc) for the last week of October.
Much of the pattern reversal will be influenced by Typhoon Lan, a rapidly intensifying storm off the coast of Japan. Over the next several days, the storm is expected to reach Super Typhoon status (equivalent to a category 4 or 5 hurricane). Though it's located thousands of miles away from Canada, meteorologists say it will have a great impact on Canadian weather patterns.
While the typhoon does not directly cause the dip in the jet stream that will cause the predicted October snowfall in Ontario, it will clear the path for colder air to move south into a trough that is expected to form over the Great Lakes area.
Meteorologists will continue to track the typhoon over the next six to ten days to get a more accurate reading of the position of the jet stream near the end of the month. If the typhoon tracks near or just east of Japan (which is what they expect), the trough will likely centre over Ontario in the Great Lakes, bringing snow to that region.
However, If the typhoon recurves further west of Japan, the trough will form over western and central North America bringing warmer weather to the region instead.
For the full scientific explanation behind this phenomenon, read the report by The Weather Network here.