Computer models continue to indicate that strong low pressure will impact our region starting late tonight through late Monday. In the meantime, we have the calm before the storm in Montreal, with a perfect late October day. The 2pm temperature at Trudeau Airport is 18C (65F), with abundant sunshine. Behind a potent cold front, Toronto sits at 7C (45F).
The aforementioned front will become the focus for very heavy rain on Sunday. As the front advances eastward, low pressure will develop along the east coast and ride northward along it towards Lake Champlain. This storm is expected to strengthen rapidly, producing a widespread, high impact weather event. Heavy rain will fall along and west of the storm track. At this time, the heaviest rain, up to 100mm (4 inches), is expected from Watertown and Kingston northeast towards Ottawa. Here in Montreal 40-60mm is likely. Another component of the storm will be strong winds. The winds will develop late Sunday from the southeast up to 60km/h, backing to the northwest Monday and increasing up to 100km/h. Winds of this strength can bring down trees and produce power outages.
With all the leaves on the ground and those likely to be stripped form the trees, urban flooding is a real concern. Expect travel delays across the entire region late Sunday and Monday. In New England and eastern Quebec, coastal flooding will also be a concern. The storm should move out of the region by early Tuesday. The weather will turn much colder behind the storm, with showers and perhaps a few flurries on Halloween day.
As of 3pm, a flood watch is in effect for the US side of the St. Lawrence Valley, along with a high wind watch. At this time, special weather statements are highlighting the storm on the Canadian side of the border. I expect official warnings will be issued at some point later today. I will update these as they happen.