Saturday, November 18, 2017

Freezing rain warning for southern Quebec

Freezing rain warnings are in place for southern Quebec this afternoon and tonight.
Strengthening low pressure will rapidly move from the central plains into the Great Lakes tonight, and down the St. Lawrence Valley on Sunday. Waves of precipitation are expected over the next 24 to 36 hours from southern Ontario into Quebec. Along the path of the storm, mixed precipitation is forecast. North and west of the system, snow will be the dominate precipitation, with as much as 25cm expected in the Laurentians and upper Ottawa Valley. South of the track towards the US border and in the Townships, look for mostly rain.

Freezing Rain Warning
Environment Canada has a wide range of warnings in effect for this afternoon and especially overnight. In Montreal, a freezing rain warning has been posted. A mix of snow and rain this afternoon, will transition to rain tonight as the temperature rises from -2C (28F) up to 4C (39F) by morning. Expect between 2-4mm of ice in Montreal. North of the city and in Ottawa, the freezing rain will last longer, with as much as 15mm possible. In Ottawa, the rain will change back to snow overnight, with as much as 10cm before it ends on Sunday. As the storm moves east of Montreal on Sunday, a strong cold front will sweep the region. Cold air will surge back into Ontario and southern Quebec, with any mixed precipitation changing back to all snow and ending in the afternoon. A couple of centimeters of snow are possible in the St. Lawrence Valley Sunday. Temperatures will fall back below freezing by noon on Sunday. Strong winds will also develop on Sunday, gusting up to 60km/h across the entire area. Travel will be highly variable and quite dangerous at times this weekend. Expect icy patches in the city. North and west of Montreal, conditions will quickly deteriorate, with lowering visibility and snow covered roads. The weather will improve on Monday.

Thursday, November 16, 2017

Strong weekend storm to bring rain and snow to Quebec

Cold air will follow the weekend storm into eastern Canada and the US. Expect temperatures to be well below normal, along with lake effect snow and snowshowers. (
A strong fall storm is forecast to develop over the Midwest US on Friday, moving across the Great Lakes and eventually down the St. Lawrence Valley this weekend. The strengthening storm is expected to bring a messy mix of rain and snow to eastern Ontario and southern Quebec. Precipitation is expected to start Saturday in Montreal, in the form of wet snow, likely mixing with and changing to rain in the city. A heavy wet snow mixed at times with freezing rain is forecast at this time north of Montreal into the lower Laurentians, as well as in the Ottawa Valley.

As much as 20cm of snow is possible north of Montreal. At this time, the forecast track of the storm is not set in stone. A change of a few kilometres will mean the difference between snow or rain for several locations. Temperatures will be cold on Friday in Montreal, warming slightly Saturday to above freezing, before cooling off Sunday. Strong winds and dropping temperatures are expected in the wake of the storm on Sunday. Winds are expected to be above 50km/h Sunday. The temperature will remain below normal next week along with the chance for some light snow or flurries.

Monday, November 13, 2017

Record cold weekend - can the snow be far behind

The first cold air of the season blasted into southern Quebec last weekend. Some locations in Quebec and Ontario recorded their first measurable snow as well. Montreal only had a trace, but more is on the way, soon.  
Temperatures across southern Quebec are slowly moderating to start the work week, after record cold Friday and Saturday. Friday was an absolute shock to the system, as a record low temperature of -8.9C (16F) in Montreal, combined with howling winds over 50km/h, to produce mid-January like windchill values. After the warm fall we have had, it was a wake up call. More cold occurred Saturday, with a record low of -9.7C (14.5F), the old record low was -8.3C (17F) set in 1973. Those temperatures were at Trudeau Airport on the island, it was much colder in the suburbs. On Saturday, the mercury remained below freezing all day with a high of -1.3C. Thankfully the wind slowly diminished for Remembrance Day services. Some snow accompanied the cold air, with a trace to 1cm in Montreal. There were some icy spots on Friday, but roads were mostly clear in the city. The cold and threat of snow had motorists scrambling to get their winter tires on. The deadline in Quebec is December 15, but that is laughable at best. Trust me when I tell you, we will have significant snow before then, guaranteed.

Saturday was beautiful, but cold. The chilly St Lawrence Seaway looking south into New York State at  Johnstown, Ontario. (ValleyWX)
First Measurable Snow
With the arrival of the first arctic air of the season, and the ground now partially frozen, the first measurable snow can't be too far behind. A clipper-type low will arrive late Wednesday into Thursday, with a light rain and snow mix. Any accumulations will be confined to the higher elevations and points north of Montreal. Behind this weak system, cooler air will filter back into the region for Friday. By next weekend, a much stronger storm will approach from the southwest, once again look for a mix changing to a cold rain in Montreal. This storm has the potential to produce measurable snow in some locations, along with gusty winds. By Sunday, cooler air returns, with any precipitation changing back to flurries. At this time, next week looks colder than normal, with the chance for more snow by mid-week.

Wednesday, November 08, 2017

First arctic blast of the season for southern Quebec

A strong arctic cold front will precede the coldest air of the season in southern Quebec. Some light snow and a rapid freeze is expected late Thursday night in Montreal. (
The first shot of polar air this fall season is forecast to invade southern Quebec late Thursday and Friday. Expect gusty winds, some snow and ice and a hard freeze by Friday morning. Arctic air has taken up residence in western Canada, with temperatures in the minus teens. A portion of the same airmass will arrive behind a potent cold front late Thursday. The front should cross southern Quebec shortly after midnight early Friday morning. Temperatures will rise to around 8C (48F) on Thursday, along with an increase in clouds. 

Frigid Friday
The arctic boundary that will cross the Great Lakes and southern Quebec late Thursday, will be accompanied by gusty winds and periods of rain changing to our first snow of the season. In Montreal a dusting to 1cm may fall, along with plummeting temperatures. Some higher elevations of Quebec and New England can expect as much as 5cm. Locations near the Great Lakes and across northwest Quebec may receive even heavier amounts. By Friday morning, the temperature in the city will be at a bone-chilling -11C (12F). This will come as quite the shock to the system after the extremely warm fall we have experienced. Friday will be windy and frigid, with high temperatures no better than -5C (23F). Gusty winds in excess of 50km/h will produce windchill readings near -18C (0F). Temperatures will moderate closer to normal levels as we head into the weekend. Saturday looks sunny at this time, with perhaps a few flurries or showers on Sunday. The average high/low for this time of year in Montreal should be plus 7C (45F) and -1C (30F) respectively.

Friday, November 03, 2017

Canada’s new weather supercomputers will improve forecasts and warnings

I had the absolute privilege of meeting the current President of the World Meteorological Organization and Assistant Deputy Minister for the Meteorological Service of Canada, David Grimes, in Dorval on Thursday. (Photo: Robert Frank)
Canada has moved to the forefront of weather computer modeling with the delivery of two High Performance Computers (HPC) from Shared Services Canada (SSC) and IBM. These high-performance computers were officially dedicated at a service at the Canadian Meteorological Centre in Dorval on Thursday, November 2. Minister of Public Service and Procurement, Carla Qualtrough was on hand for the unveiling. But, as a weather nerd, it was Assistant Deputy Minister for the Meteorological Service of Canada and current President of the World Meteorological Organization, David Grimes, who caught my attention. It was an absolute honour to talk to him about the new computers and weather in general. A video presentation of last weekend’s intense storm, as displayed by the new supercomputer modeling output, was beyond impressive. According to Grimes, these computers will make Canada, “one of the best modeling centers in the world”. “Our early-warning system has been greatly enhanced,” he added. The new HPC solution is the fastest recorded computer platform within the Government of Canada, and among the fastest in the world. 

The super computers will allow for complex weather programs and models, involving over 10 billion data points, to be processed much quicker. The end result for Canadians will be more accurate and timely forecasts and warnings. What was exciting for me to discover was that my Davis Vantage Vu weather station, in my backyard on L’Ile Perrot, is likely one of those data points. Information is pumped into these computers from all around the country and the world. Weather knows no boundaries. If you are processing weather data and uploading it to the web, it will likely be used in one calculation or another.

Computer weather modeling has become crucial in recent years.  It allows forecasters to input current weather data, along with additional information, variables and parameters, to basically map out how weather systems will move in both the short and long-term. According to Grimes, a typical model run can take around seven hours, but that will gradually be reduced over the next decade, down to almost real time within ten years.

The HPC is five times faster than the old Environment and Climate Change Canada (ECCC) computers, processing data at an astonishing 2.444 trillion calculations per second. The HPC is primarily for ECCC weather predictions, but additional organizations will also benefit from this resource. Health Canada for air quality alerts, Fisheries and Oceans Canada to support ocean modeling and Public Safety Canada to support environmental emergency prevention – just to name a few. Today’s new supercomputers are 70 million times faster than Environment Canada’s first supercomputer purchased in 1974.

The new ECCC supercomputers were dedicated to; Kenneth Hare above, and Harriet Brooks below.
(ECCC Photo)
The new supercomputers were named for two late distinguished Canadian scientists: Harriet Brooks, Canada’s first female nuclear physicist, who worked with Marie Curie and contributed to research on radon gas, and Kenneth Hare, Canadian environmental science advocate, who warned about carbon-driven climate change long before many others were paying attention.

Tuesday, October 31, 2017

Widespread damage across Quebec in the wake of storm

A deep coastal storm produced damaging winds across southern Quebec on Monday, including the Eastern Townships shown above. (Photo: Sandra Thomson) 
The storm is over but the scars remain. Montreal was rather fortunate, as the worst of the powerful coastal storm seemed to split the city. Deep low pressure moved just west of Montreal, producing near record low barometric pressure (976mb) and winds up to 80km/h. We were lucky ones. Other regions had winds in excess of 100km/h, combined with torrential rains and flooding.

In the wake of the storm, nearly 1.5 million customers were without power in New England, Quebec and Ontario. As of 11am Tuesday, 40,000 Hydro Quebec customers were still without power across the province. The utility has over 700 personnel on the job. The storm also took down thousands of trees, many onto homes and cars. Peak wind gusts over the last 36 hours included, 214km/h (133mph) on Mount Washington, New Hampshire, 101km/h (63mph) at Burlington, Vermont, 109km/h (68mph) at Port Menier, Quebec, 87km/h (54mph) at Saint Hubert and 80km/h (49mph) at Trudeau Airport in Montreal. Warm air circulated along the east side of the low pressure, with 28 record highs reported in Quebec on Monday. Thunderstorms even rattled across Quebec City producing additional heavy rain and wind damage.

Hydro Quebec has 700 workers on the job, after strong winds knocked power out to over 200,000 Quebec homes. Above a crew works in Knowlton, Quebec. (
West of the storm track, extremely heavy rain fell. Flooding occurred in Ottawa/Gatineau, where 112mm of rain fell in less than 48 hours. Today a flood watch remains in effect across the Rideau Valley. Major flooding was also reported in New Hampshire, where numerous rivers overflowed their banks, sweeping away roads and in some cases entire homes.

Cold air has settled into southern Quebec for Halloween. Gusty west winds will continue today, diminishing towards sunset. Temperatures will be near 4C (39F) for trick or treating. Indications are that the cool weather and perhaps even flurries or light snow will occur during the first week of November. Now might be the time to get those snow tires on.

Monday, October 30, 2017

Damaging winds for Montreal

NOAA water vapor image of powerful low pressure moving north up the Hudson Valley, (dry slot in the middle of the image) towards Montreal this morning.
A high wind warning remains in effect for the entire region this morning. Winds have been gusting in excess of 100km/h across the Eastern Townships into Vermont overnight. In Montreal, gusts have been up to 60km/h, but they will increase towards 90km/h this morning. Deep low pressure will move north from the Hudson Valley towards Massena, New York today and into western Quebec tonight. Extremely low barometric pressure readings have been occurring across our area, with 977mb here at my home on L'Ile Perrot and 972mb at Ottawa. This represents the lowest pressure of the year for L'Ile Perrot. Also, the pressure has fallen 20mb since midnight, indicating just how strong this storm is. Southeast winds and a dry slot cut off precipitation here in Montreal overnight, with 25 to 30mm recorded. On the cold side of the storm in Ottawa, heavy rain fell all night, with in excess of 50mm falling. The weather is also very warm in Montreal this morning. With a temperature of 19C (66F) at 6am, Montreal is the warmest location in the country.

Storm damage in New England overnight. (NBCCT)
The wind has caused widespread damage and power outages across New England and Quebec. In Quebec, Hydro is reporting 157,000 customers without power as of 7am. That number will only grow as the strongest winds move into metro Montreal.

As the storm moves north of Montreal today, winds will shift to the southwest and west and eventually diminish a little by evening. Temperatures will also drop rapidly today back into the single digits. Showers, some heavy are expected through early afternoon.