Thursday, July 20, 2017

The ring of fire dominating the weather in Montreal

Montreal remains on the northern edge of the "ring of fire". While areas to our south are experiencing searing heat this summer, the weather remains unsettled and humid in southern Quebec. Heavy rain, flash flooding and severe weather has been occurring all around the edge of the high pressure ridge. (AccuWeather)

The continent appears to be split into two distinct weather patterns this summer: extremely wet or dangerously dry. We all know how wet a year it has been here in southern Quebec, across eastern Ontario and into northern New England. At the same time, they are desperately hoping for rain in fire-ravaged B.C. The culprit this July is a rather large area of high pressure anchored over the central US. Under that dome, temperatures have soared into the upper 30s, with very little rainfall. The influence of this high pressure occasionally nudges into western Canada, keeping that region hot and dry as well. Around the ring of high pressure is a region of instability, with frequent showers and thunderstorms. In many cases, the storms have been severe, with flash flooding. Flooding has affected portions of Arizona, the Great Lakes, New England and southern Quebec, south along the Atlantic Seaboard into the US southeast.
Smoke from the British Columbia wildfires has now spread as far east as Manitoba (dark grey). There is a chance we may even see some in Ontario and Quebec before the end of July. (Environment Canada)
Here in Montreal, we are dealing with dripping-wet humidity this week, along with frequent clouds and showers. Temperatures have been close to the normal high of 27C (81F), but once the humidity is factored in, it has felt like the middle 30s. This familiar pattern will remain in place through Friday, before slightly less-humid air moves in late Saturday. The dry air will be short-lived, as another round of showers and thunderstorms is expected on Monday.

Fire damage from Loon Lake, BC. (CBC)
BC Wildfires
In western Canada, more hot and dry weather is forecast in Alberta and Saskatchewan to end July. In B.C., temperatures will trend a little cooler, but unfortunately no appreciable rain is in the forecast. The state of emergency, in effect since the start of the month, has been extended for another two weeks. Over 140 fires are burning across the province, having already consumed over 3200 square kilometres. Of those fires, 27 are considered major, with 15 threatening communities. BC resources are being augmented, with an additional 100 firefighters expected to arrive this week from Ontario. They will join 830 already on the ground from across Canada, including 45 from Quebec and 54 from Australia. To date, 41 homes and three dozen trailers have been lost to the fires. The cost to battle the wildfires has now exceeded $100 million, with over 40,000 residents evacuated. Outdoor fire bans remain in effect for the foreseeable future. Smoke from the fires has drifted as far east as Manitoba, and into the central portions of the US. Air quality advisories have been in effect on almost a daily basis across southern BC and Alberta.

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