Strong fall storm forecast to dampen Halloween spirits

In keeping with the trend this October, Southern Quebec will have a wet Halloween. Montreal has measured nearly 200mm of rain this month, more than double the normal of 90mm.

A strong low pressure system is forecast to develop over the Ohio Valley on Thursday and deepen rapidly as it  lifts northward across the Great Lakes and into central Ontario. The storm is expected to produce a wide variety of stormy weather from heavy snow north and west of the track, to severe thunderstorms and powerful winds south and east of the low.

Heavy rain is forecast to develop on Thursday across the St. Lawrence Valley, making for a gloomy wet Halloween. Up to 50mm may fall in Montreal, with even more possible south and west of the city.

Showers are expected to develop in Montreal on Thursday afternoon, becoming a steady rain by the evening hours. Heavy rain is forecast overnight into Friday morning, with as much as 50mm (2 inches) expected in Montreal. October has been very wet for the city, with close to 200mm (8 inches) of rain to date. The average rainfall for Montreal is closer to 90mm. The heavy rain will produce rapid rises on rivers and streams in the region. Some minor flooding is possible. As well, tons of leaves will hit the ground, clogging sewers. In addition to the heavy rain, a swath of wet snow is forecast across central Ontario into central Quebec, with as much as 15cm possible in places like Val d'or .

The system will be a very deep fall storm, with strong winds anticipated on Friday. As the storm lifts into central Quebec, southwest winds will approach 100km/h (60 mph) in the St. Lawrence Valley including metro Montreal. Winds this strong are capable of tree damage and power outages. Wind gusts may approach hurricane strength of 120km/h (75mph) across portions of the eastern Great Lakes and northern New York. Numerous watches and advisories have already been issued, and I expect weather warnings will be needed for Montreal and southern Quebec later today as the storm develops.

Temperatures will be very mild on the east side of the low pressure area, reaching into the middle teens in Montreal Wednesday and on Halloween. As the storm moves off to our north temperatures will drop rapidly on Friday, down to 5C (41F). A few flurries are even possible on Friday and Saturday across southern Quebec and eastern Ontario.

Remains of tropical storm Olga to soak southern Quebec

The remains of poorly organized tropical storm Olga will move northeast along a frontal boundary, producing a rainy, windy Sunday for southern Ontario and Quebec. (AccuWeather.com)

Tropical storm Olga quickly developed on Friday over the northern Gulf of Mexico and almost immediately became absorbed by a frontal boundary. The system remained rather weak and disorganized, with gusty winds of 90km/h (50mph) and heavy rainfall being the main threats. Isolated coastal flooding was also reported over east Texas and southern Louisiana. As of late Friday evening, what was left of the storm was located over central Louisiana.

Meanwhile high pressure was building into southern Quebec, with a cool, frosty start to the weekend in Montreal. Saturday will remain dry, with sunshine and cool weather forecast. Highs will reach 12C (54F). Clouds will be on the increase early Saturday evening, with temperatures dropping rapidly after sunset and then leveling off around 5C (41F). The remains of Olga will advance northeast on Sunday across the Ohio Valley and into the Great Lakes. Expect rain to develop before sunrise over southwestern Quebec, becoming moderate at times, with 20 to 25mm likely. This will add to our already extremely soggy October in Montreal, with 160mm down so far. Normal rainfall is only 89mm for the entire month. Sunday will be cool, with highs struggling to reach 10C (50F). Condtions will be breezy as well, with winds gusting to 50km/h.

Skies will clear on Monday, with very mild highs of 16C (60F). The good weather will be short-lived, as a deepening storm system and cold front will bring rain and even some snow to locations in Ontario and Quebec by the middle portion of next week. The Halloween weather in Montreal looks gloomy and wet for now. Much colder weather will follow this storm system as we head into early November.

Southern Quebec remains between major storms

Heavy snow is making for very difficult travel this morning across southern Manitoba and eastern North Dakota. (NDSP Photo)

The best weather across the country is right here in southern Quebec and eastern Ontario as we head into the Thanksgiving holiday weekend. High pressure is dominating the skies, with bright sunshine and above normal temperatures. These conditions will prevail over the weekend, with just a slight chance of a few showers late Saturday night as a cold front crosses the region. Sunshine returns Sunday and Monday, with temperatures just a touch cooler. The high will be near 17C (63F) Friday and Saturday, 13C (55F) Sunday and Monday.

Major Storms
While we have nearly perfect fall weather here in Montreal, major storms are impacting the east coast and across the Prairies and northern plains. A large early winter storm is hammering the Rockies and plains with heavy snow and winds in excess of 80km/h. Up to 3 feet of snow is forecast in sections of North Dakota by Saturday night. Denver, which had highs over 27C (80F) just two days earlier, was well below freezing with heavy snow on Thursday. The snow and wind will spread into southern Manitoba and northwest Ontario today, where winter storm warnings are in effect. Travel will become nearly impossible today across the Dakotas and southern Manitoba, with heavy wet snow and winds up to 100km/h. Power outages and tree damage are likely. The snow will taper off Saturday as the storm weakens and moves into Ontario.

The Atlantic Ocean spills onto North Carolina State Route 12 near Rodanthe, North Carolina on Thursday. A strong Nor'easter located well offshore continues to produce coastal flooding. (OBX Today)

Along the eastern seaboard, a strong Nor'Easter has been blasting coastal regions from North Carolina to New England with heavy rain, strong winds and flooding. Sections of Highway 12 were washed out late Thursday along the Outer Banks of North Carolina. The storm will drift northeast over the weekend impacting coastal Nova Scotia with heavy rain, strong winds and high seas.

Strong October thunderstorms produce flooding in Montreal

Strong thunderstorms produced widespread flash flooding during the evening commute in Montreal. (ValleyWeather Photo)

Frost Advisory in effect for southern Quebec.

A slow moving warm front became the focus for strong thunderstorms on Tuesday across southern Quebec and especially here in the Montreal region. Torrential rain fell on the city between 2 and 6pm producing widespread flash flooding across several regions of the city. Wicked lightning and thunder accompanied the storms, more common for Montreal in July than October.

A record breaking 48.4mm of rain fell at Trudeau Airport on Tuesday, surpassing the previous daily high of 34.3mm set in 1945. The rain overwhelmed sewers flooding basements and closing several roads including Highway 20 at Boulevard Angrignon. The flooding and heavy rain made for a long evening commute for many. The storms were part of the same weather system that produced record high temperatures across southern Ontario. Over a dozen record highs were observed on Tuesday, including 31.8C (89F) in Toronto, surpassing the previous record of 29.5C (85F) set in 2002. It was also the warmest high ever recorded in that city in October. While southern Ontario was basking in summer warmth, flurries and temperatures near 0C (32C) were occurring across northwestern portions of the province.

Montreal remained in the cool, moist air to the north of the front for most of the day, finally warming to 17C (63F) by the early evening.

The new section of Highway 20 near Boulevard Angrignon, was turned into a lake during the severe thunderstorms Tuesday afternoon. Transport Quebec was forced to close the road in both directions , snarling traffic for hours. (CTV)

First frost
Behind this weather system, much colder air will pour into southern Quebec, with a good chance for the first frost of the season early Wednesday morning. Frost advisories are in effect for the entire region, including metro Montreal, with overnight lows forecast between 0C and 2C (32 to 36F) in the city and as cold as -3C (27F) north of Montreal. Frost is also expected in eastern Ontario away from the St. Lawrence River.