Monday, July 31, 2017

Humidity and thunderstorms forecast to return to Montreal

The weather this past weekend was perfect for whatever outdoors plans you had. I chose the 37th Annual Granby Antique Car Show in the Eastern Townships. A perfect venue, light breeze, low humidity and bright sunshine resulted in hundreds of cars on display and thousands of spectators.
After an absolutely perfect weekend, with full sunshine, low humidity and temperatures in the middle 20s, showers and thunderstorms will be on the increase today to end July. High pressure dominated the weather across southern Quebec, giving us a very rare stretch this summer with no rain. A frontal system will begin to impact Montreal today, signalling a change in the air mass. We can still expect partial sunshine, but with isolated showers and thunderstorms developing in eastern Ontario this afternoon, and moving into southern Quebec late in the day. The biggest threat from any developing thunderstorms will be heavy rain, as some cells will be slow moving.

The high temperature today, and through the entire week, will be in the 27C to 30C range (80 to 85F). As the month draws to a close, Montreal has yet to record a 30C high temperature. Normally we have 5 such days, with July 2016 featuring 6 days above 30C. Overnight lows this week will be on the mild side, around 19C (66F), In addition to the warm temperatures, humidity levels will be on the rise, reaching oppressive levels by Thursday. The risk for showers and thunderstorms will exist each day this week, peaking late Friday with the arrival of a cold front. At this time, next weekend looks decent, with clearing skies, cooler temperatures and low humidity.

The weather has been very active across North America over the past week. Heavy rain and thunderstorms occurred across a portion of the middle Atlantic states, with numerous reports of flash flooding. Meanwhile, the weather remains hot and dry across western Canada, with strong thunderstorms occurring along the periphery of the heatwave in Saskatchewan and Manitoba. Temperatures soared into the upper 30s on Sunday, with Assiniboia, Saskatchewan, a little Prairie town I am very familiar with, reaching 37.7C or 99.8F. Mankota, Saskatchewan, near the Montana border, was the warmest placer in Canada on Sunday, reaching 38.2C (101F).

Tuesday, July 25, 2017

More rain, more flooding - our summer of discontent

A quick thinking employee from Bed Bath and Beyond, checks on a stranded motorist in Kingston, Ontario on Monday. (Photo via Twitter @YGKtraffic)
Low clouds, mist and a September-like chill prevail across southern Quebec this morning, as a nasty upper-level low slowly spins eastward. The storm produced torrential rain, strong winds and cold temperatures on Monday. The high in Montreal was a mere 20C (68F), reached in the wee hours of the morning. Most of the day was spent in the middle teens as temperatures fell with the onset of heavy rain. The real story with this system was the rainfall. Trudeau Airport measured 17.8mm, but amounts rose quickly as you headed west down the 401. Here on L'Ile Perrot, I recorded 28.8mm, with 32mm at St. Anicet. In Ontario, Kingston reported 102.2mm, Brockville 102mm, Ottawa 79mm and Kemptville, 71.3mm. There were isolated reports of as much as 150mm in some locations along the Thousand Islands Parkway, and north of Kingston. Conditions were the same south of the St Lawrence River in upstate New York. Flood warnings were in effect for St. Lawrence County, New York, where upwards of 4 to 6 inches of rain fell.

Widespread flooding was observed, with several road closures across eastern Ontario. Numerous accidents were reported along area highways, including Autoroute 20, west of Montreal near Coteau du Lac. Highway 2 was closed near Johnstown, Ontario due to several metres of water covering the roadway near the rail bridge. Isolated power outages also occurred, with as many as 8000 Hydro Quebec customers without power Monday afternoon. That number is down to 1000 as of Tuesday morning.

Flood warnings and watches have been posted for several watersheds in Ontario as a result of rapid runoff. Water levels on the Kemptville Creek and Rideau River basin will be running well above normal for the next few days. All this water will be rushing down the St. Lawrence River towards Montreal over the next week. All waterways across southern Quebec and eastern Ontario remain dangerous for any activities, and vigilance is strongly encouraged.

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.

Friday, July 14, 2017

The 30th Anniversary of the Decarie Expressway flood

Firefighters rescue trapped motorists from the Decarie Expressway after thunderstorms generated historic flash flooding on July 14, 1987. (Radio Canada)
Tuesday, July 14, 1987 dawned hot and humid across southern Quebec, as it had been for the previous week. Montreal recorded high temperatures in excess of 32C (90F) from July 9th through the 14th, including a record high of 34C (94F) on July 13th. Accompanying the high heat was stifling humidity levels. Montreal is a city that is accustomed to very humid summers, but these levels were off the charts. The elevated humidity had saturated the atmosphere, similar to the tropics, not southern Canada. On the morning of July 14th, a strong cold front was lying west of Ottawa. In addition to the the front, low pressure had developed in southeast Ontario. Some partial sunshine early on July 14th in Montreal, allowed the mercury to climb to 30C (86F) before the noon hour, adding fuel to the atmosphere. The air mass had become unstable and volatile, all the conditions were perfect for powerful thunderstorms.

Widespread flooding trapped hundred of motorists in Montreal on July 14, 1987. (Radio Canada)
The storms would first develop southwest of Montreal around 11am, approaching the city shortly afterwards and moving from Chateauguay northeast across the Island of Montreal and into Laval. With plenty of available moisture, the thunderstorms would produce torrential rainfall for several hours, training over the same locations. Four separate thunderstorms cells in total would impact the city from 11am through 3pm. In some cases, a months worth of rainfall would occur in less than 2 hours. Trudeau Airport measured 57.4mm (2.25"), but it was the central portion of the city and the downtown core the would be hardest hit. I lived on the waterfront in Verdun at the time, and my rain gauge overflowed at 100mm (4 inches).

Officially, 102.2mm (4.02") fell at the McGill Observatory on McTavish, 86mm (3.38") of that fell in less than one hour. At Parc Lafontaine, 103mm (4.05") was recorded, with unofficial reports of as much as 180mm (7.1"). The deluge would overwhelm the sewer system, designed for no more than 36mm (1.41") per hour. Water would pour into highway underpasses, basements, businesses and of course the Decarie Expressway. Over 300 motorists became trapped in their vehicles on the Decarie alone, requiring rescue from the Montreal Fire Department. Nearly 400 cars would be abandoned. Traffic was gridlock across the city as major routes such as Highway 20 at 1st Avenue in Lachine and the St Remi Tunnel became flooded as well. The Metro was forced to close as a result of flooding on several lines. The evening commute would last into the wee hours of July 15th.

Flash flooding on Atwater Street in downtown Montreal, July 14, 1987. 
(The Montreal Gazette)
Wind gusts of 80km/h occurred with the thunderstorms, knocking out power to over 350,000 homes. Along with the loss of power, came the loss of air conditioning and electronic pumps. The wind snapped trees and power lines, but it was the rain that created the massive damage. In all, over 40,000 homes in the city sustained some form of water damage. As is often the case, much of it was not covered by insurance. Total losses for the storm exceeded $220 million. Sadly two fatalities were reported, one man drowned in his car in a Cote-des-Neiges underpass, while a second person was electrocuted.

Water pours down Mount Royal Avenue during flash flooding on July 14, 1987. 
(The Montreal Gazette)

Monday, July 10, 2017

Thousands forced to flee British Columbia wildfires

Highway 97 near Ashcroft, B.C. remains closed as a fire burns out of control near the community, 90km west of Kamloops. (BC Transportation via Twitter)
Nearly 300 wildfires are burning across interior British Columbia, according to the BC Wildfire Service. Of these, at least a dozen are large, intense and out of control. This includes a fire burning near 100 Mile House, that prompted the evacuation of the entire community Sunday. This increases the number of evacuees in B.C. to over 10,000. More are likely today, with a provincial state of emergency now in effect. Nearly 2000 firefighters are battling the fires, with help coming form Alberta. The fires are the result of hot, dry weather, with frequent lightning strikes prompting new fires daily. The weather has been hot across all of western Canada, with high temperatures on Sunday in the middle 30s. A brief break is expected in the form of thunderstorms by Tuesday, before high pressure builds back in, with more extreme heat. The heatwave is expected to continue right through the end of the week. The hot weather stretches into Alberta and Saskatchewan, as well as a large portion of the western US.

Stormy in Eastern Canada
It was a much different story here in Montreal, and across a large portion of eastern Canada. Our wet and frequently cool summer continues, with little relief in sight. Early Saturday morning, a strong thunderstorm with wild lightning and up to 25mm of rain in less than 30 minutes, moved from L'Ile Perrot towards the downtown core of the city. The storm produced some minor flooding, especially off island to the west. The entire weekend was unsettled, with below normal temperatures and frequent clouds, showers and thunderstorms. The weather this week will follow a similar one to that of the entire summer to date. More showers and thunderstorms are possible each day through the weekend. Temperatures will struggle to reach the normal high of 26C (79F) each day. Sadly this trend is expected through the end of July. Montreal has had measurable precipitation, on 6 of the 10 days this month, with 37.8mm of rain so far. In Ottawa 98.4mm of rain had fallen through Sunday. The July average for the entire month is 91.9mm.

Friday, July 07, 2017

Don't like the weather - just wait a few minutes

Water from Lake St Louis continues to produce minor flooding in shoreline communities in and around Montreal. Above, flood waters creep in Summerlea Park in the borough of Lachine on Wednesday. The municipality has raised the level of the walking path as well as built some reinforcements to hold the water back.(Valley Weather Photo)

Scattered thunderstorms are possible in Montreal and across southern Quebec today, as a warm and humid air mass is in place. Some of the storms may produce heavy rain and gusty winds. Temperatures will be near 27C (81F), along with elevated humidity levels. Temperatures will be slightly cooler tonight and into the weekend, with lows down to 16C (61F), and highs both Saturday and Sunday near 24C (76F). Unfortunately the weekend will display the same weather we have become accustom do for the last few months. I hate to reuse the same word over and over again, but unsettled comes to mind. The atmosphere will be busy, changing frequently and quickly, with fair skies in the morning, building instability, and showers or thunderstorms in the afternoon. This type of weather will prevail into early next week.

Where is all the hot air? 
If you want heat, go western North America. However, the sunny, hot weather comes at a price. Wildfires are running rampant from California to Montana and in especially hard-hit Colorado. Heat emergencies have been declared in many communities. The hot air has arrived in Canada, from southern interior B.C., eastward into Alberta and Saskatchewan. Temperatures this week have been in low to middle 30's, and may approach 40C along the Montana border by next week. Heat warnings have been issued by Environment Canada for several locations in Alberta and southwest Saskatchewan.

As we head into summer vacation time in Quebec and Ontario, please be extra careful around any body of water. Levels on the Great Lakes, Ottawa and St Lawrence Rivers continue to run very high. When you add any wind to the mix, the water can easily overwhelm a boat, or make swimming dangerous. Minor shoreline flooding also continues in several communities.

Tuesday, July 04, 2017

A break in the soggy weather for Montreal

A spectacular rainbow developed at sunset over the St Lawrence Valley late Sunday. It was a perfect end to a not-so-perfect weather weekend in Montreal. (Valley Weather Photo)
After a seemingly endless streak of wet weather, the sun is out today, Tuesday, July 4 across the entire region. Since early April, it has rained on nearly every second day in southern Quebec and eastern Ontario. During June, Montreal measured rainfall on 21 of the 30 days. In Ottawa, it rained on 23 of 30 days, including a stretch of 18 consecutive days through July 2. Water levels remain fast and high on area lakes and rivers. Montreal has a 30 percent chance of showers today, before high pressure settles in for a 36 hour dry spell. It is not much, but we will take it. Sunshine will prevail through Thursday morning, along with temperatures warming into the middle and upper 20s.

A tornado moves over Sebago Lake in western Maine on Saturday, July 1st. It was one of four reported in the state on Saturday alone, double the annual average. (TWC)
While Montreal had a few showers and thunderstorms this past weekend, the bulk of the heavy rain fell across the Adirondacks in New York, into central Vermont. Several locations reported severe weather, with hail, strong winds and torrential rains. Well in excess of 75mm of rain fell on already saturated ground, producing widespread flash flooding. Washouts and closures were reported on several major roads in Vermont, including Interstate 89. Severe thunderstorms were also reported in Maine, where 4 tornadoes occurred on Saturday, July 1. Maine averages only two tornadoes for the entire year.

The entire region will be under high pressure for the next two days, before more clouds, showers and thunderstorms arrive for Friday and Saturday. The humidity will be on the rise as well as we head into Thursday. Meanwhile in Western Canada, heat warnings are in effect for portions of southern Alberta. A prolonged heatwave is forecast this week for interior B.C., Alberta and Saskatchewan. Some locations near the US border are expecting high temperatures in the middle and upper 30s.

Saturday, July 01, 2017

Mother Nature's fireworks on display this Canada Day

Mother Nature will provide the fireworks today, with increasing clouds, and more showers and strong thunderstorms forecast for Canada Day in Montreal and Ottawa.
Mother Nature will provide natural fireworks today, as rounds of showers and thunderstorms are forecast for the entire region. Montreal, southern Quebec, Ontario and New England remain in a soupy air mass this Canada Day. The atmosphere will remain primed today for heavy showers and thunderstorms, as it has been most of this past week. Temperatures will be warm, 24 to 27C (75-80F), along with high humidity and very muggy conditions.

Flooding is occurring in parts of northern Vermont after torrential rain Thursday and Friday. (WCAX TV) 
On Thursday and Friday, strong storms swept across portions of the St Lawrence Valley into northern Vermont and New York. Flash flooding was reported in several locations, with roads washed out. More flooding is likely today as the thunderstorms fire up. A flood watch is in effect across all of upstate New York and Vermont. Thunderstorm watches and warnings may be likely for portions of southern Quebec and eastern Ontario including Ottawa as the day progresses. Please keep this in mind of you have any outdoor Canada Day plans. The heavy rain is falling on already saturated ground, so the potential for flooding exists across the entire region. In June, Montreal recorded 135.2mm of rain, well above the normal June rainfall of 89.3mm. On L'Ile Perrot, I recorded 127.5mm, with 130mm in Ottawa. This of course is all falling on top of the waterlogged spring we had.

After today's storms, Sunday will dawn slightly cooler and less humid, but still with a chance of showers and thunderstorms in the afternoon. Conditions should improve on Monday, with dryer weather forecast for the first time in over a week. The sunny and dry conditions should persist into early Thursday.