Thursday, May 24, 2018

Record heat and snowstorms - just another May day in Canada

A record-breaking, shocking snowstorm slammed parts of western Newfoundland on Thursday. Over 30cm fell in Gander. (CBC Photo)
Thursday was a wild day across portions of New Brunswick. A strong cold front slipped south across the province, allowing chilly maritime air to invade from the northeast. Strong thunderstorms developed along the front, producing heavy rain, hail and lightning. Winds gusted in excess of 100km/h in several locations. The severe thunderstorms also impacted portions of down east Maine and Nova Scotia. Behind the front, cold air filtered into the region changing the rain to snow. As much as 5cm fell across northern portions of New Brunswick.

In Newfoundland, a record-setting storm dumped 32cm of snow on Gander. The heavy wet snow closed schools and made for poor travel conditions, just one week before June. Unseasonable cold weather is forecast to continue across Atlantic Canada, spreading westward into Quebec this upcoming weekend.

While cold weather prevailed in the east, record breaking warmth surged across western Canada, and as far north as Fort Smith, in the Northwest Territories. The community smashed a 70 year old record, with a daytime high of 30.2C (86F). In Alberta, Fort McMurray also established a new record at 32.5C (91F), and Edmonton 29.4C (85F). Dozens or other record highs occurred from B.C. to Manitoba.

Backdoor Cold front
Friday will be sunny and summer-like in southern Ontario and Quebec, with an increase in humidity and high temperatures of 27 to 30C (81 to 86F). The good news ends there, especially for southern Quebec. A backdoor cold front will settle south across the province on Saturday, with cooling temperatures and widespread showers and thunderstorms. Northeast winds will develop, dragging the cold air southwest from the frigid waters of the Gulf of St. Lawrence. A very sharp thermal boundary will be set up somewhere in the St. Lawrence Valley this weekend, with cool showery weather to the north and warm and humid weather to the south. At this time, high temperatures in Montreal on Saturday and Sunday, will range from 16 to 18C (61 to 65F). However, just to our south and west, highs may push into the middle and upper 20s as conditions remain warm and muggy in Ontario. Rain is expected to accompany the cooler weather in southern Quebec, with perhaps as much as 25mm (1 inch) over the weekend.

Wednesday, May 16, 2018

Severe weather season in Montreal - watch vs warning

Severe thunderstorms result in millions of dollars in damages every year across Canada. The threats are many with summer thunderstorms, including flash floods, strong winds, large hail, lightning and tornadoes.
Temperatures are slowly warming up across southern Quebec, and it won't be long before thunderstorms begin rattling around. With the increase in heat and humidity, will come the inevitable thunderstorm. Southern Quebec averages 15 to 17 thunderstorm days every year, most occurring between late May and early September. Severe thunderstorms are particularly menacing, because they come with several different high impact threats that can occur in any one region. They form very quickly, in lines or even as single cells. Tornadoes and lightning are among the greatest dangers within a thunderstorm. Lighting kills an average of 10 Canadians each year, while injuring 150 more. That being said, it is flash flooding, hail and strong winds that cause the greatest damage in Montreal.

Here are just a few examples of strong storms in Montreal. On August 22, 2017, a severe thunderstorm and microburst in the Borough of NDG, levelled thousands of trees and snapped hydro poles like twigs. On May 29, 1986, and again one year later on the same date, strong thunderstorms produced copious amounts of large hail, up to 12mm in diametre. The result was over $75 million dollars in damages to homes and cars across metro Montreal, and millions more in crop losses in southern Quebec. Of course the most famous thunderstorm in Montreal, occurred on July 14, 1987, when over 100mm of rain in less than 2 hours, flooded large portions of the city, including the Decarie Expressway. Known as the Decarie Flood, the storm resulted in two fatalities and $200 million in damages.

WATCH vs WARNING
The best way to protect yourself and property from summer storms is through awareness and vigilance. During hot and humid weather, listen for updated watches and warnings. Environment Canada will post a Severe Thunderstorm Watch, typically for a large area and a wide time frame. They are posted when conditions are favourable for severe thunderstorm development, but none are occurring yet. The watch is simply to advise the public that a threat does exist for severe weather. A Severe Thunderstorm Warning is an immediate call to action for a smaller portion of the watch area. The watch means strong storms have developed and are being tracked by Environment Canada. These storms are expected to impact the warned region. Keep in mind that thunderstorms form and dissipate very quickly. They are micro scale weather events, impacting a small geographical region at any given time. Therefore it is important that you check the time and source of the warning. Often social media will share information that is dated. Warnings are typically in effect for short periods of time for any given region, often less than one hour. They are updated often as the storms move through the area. The best course of action during severe thunderstorms, is to move inside, away from windows and doors. If outside, find the lowest point, make yourself as small as possible to avoid being struck by lightning.  More lightning safety tips can be found here.

Environment Canada continues to upgrade the doppler radar network across Canada, which will greatly improve severe weather forecasts as well as watch and warning times. You can read more on the new radar technology here.

Thursday, May 10, 2018

Flood risk on the decline - fire risk on the rise in Quebec

The warmer weather this week has allowed many of the tulips in Montreal to bloom. However a frost advisory is in effect Thursday night across the Eastern Townships, where lows could dip below freezing. 
The spring flood risk has somewhat stabilized across southern Quebec. Dry conditions over the past week have allowed the rivers around Montreal to level off. The story is much the same in the Ottawa Valley. South of Montreal, Lake Champlain remains at flood stage, with the high water levels expected to travel north into the Richelieu Valley. According to Hydro Meteo, a flood warning is now in effect for the Richelieu River. At this time however, only minor flooding is forecast. Since May 1st, only 18.6mm of rain had fallen in and around Montreal. On Thursday, a few showers were forecast, but this will have little impact on water levels. The average rainfall for Montreal in May is 81.2mm. By comparison, during the historic Quebec floods of 2017, 160mm fell in April and 124mm in May.

A large portion of southern Quebec is in the elevated fire risk zone (yellow and orange). Any outdoor burning should be done with extreme vigilance. (SOPFEU)
Reconsider outdoor burning
Expect a very dry airmass to arrive behind the cold front Thursday evening. Temperatures will fall back below normal, along with low relative humidity values. According to SOPFEU, the forest fire watchdog in Quebec, the forest and brush fire risk is elevated for metro Montreal and the Monteregie, and very high for the Townships and Quebec City. Any outdoor burning should be done with extreme care. At this time, two fires are burning in the province, comprising 25.6 hectares (63 acres).

Looking ahead to the upcoming weekend and early next week, little if any precipitation is expected for Montreal. The dry breezy weather will only add to the fire risk. Colder temperatures will arrive Thursday night, with lows forecast close to the freezing point in several locations. Some frost is likely north of Montreal and across the Eastern Townships. Temperatures through the weekend will remain chilly in Montreal, with daytime highs of 15 to 17C (59 to 63F) and lows from 6 to 8C (43 to 48F). Warmer weather is expected by next Monday, as highs climb back into the middle 20s.

Saturday, May 05, 2018

Fierce winds create widespread damage - 250,000 without power in Quebec

Firefighters on L'Ile Perrot, along with their colleagues in Montreal, were busy last night responding to dozens of calls for damage generated by 100km/h winds. (ValleyWX)
A strong cold front swept across southern Quebec and Ontario Friday afternoon, accompanied by the first round of severe thunderstorms this season. Thunder and lightning along with heavy rain, greeted drivers returning home in Montreal, as the storms arrived just in time for the evening commute. However the real story for Ontario and Quebec was the strong winds that developed behind the front. Wind gusts in excess of 100km/h created widespread damage and power outages. The wind increased rapidly in Montreal around 9pm Friday evening, and by midnight, over 250,000 residents were in the dark across the southern portion of the province. A peak gust to near hurricane force, 117km/h (72mph), was observed at Trudeau Airport. The wind managed to keep first responders busy, with dozens of call for trees falling onto power lines, cars and homes. On 6th Avenue in Lasalle, the wind took down a string of power poles. On the Louis Bisson Bridge into Laval, a semi was nearly blown into the river below. Transport Quebec closed Highway 13 overnight to remove the truck.

Widespread damage was reported in southern Ontario from the wind storm Friday. Hurricane force winds occurred in several parts of the province. (CBC)
 In Ontario nearly 300,000 customers were without power. A peak gust to 126km/h was reported in Hamilton, 119km/h in Toronto and 96km/h in Ottawa. Widespread damage was reported to trees, roofs and cars. Two deaths occurred in Ontario as a result of the wind. Hundreds of flights were delayed or cancelled after a ground stop was ordered at Pearson Airport.

South of the border in New York and Vermont, a tornado watch was posted for the same system. As of this time, no tornadoes were observed, but dozens of  incidents of wind and hail damage were reported.

Friday, May 04, 2018

Heavy thunderstorms & strong winds forecast for Montreal

A strong cold front will produce severe thunderstorms for portions of southern Quebec and Ontario today. (AccuWeather)
Wind warning posted for metro Montreal.

A potent low pressure system will slide from the upper Great Lakes into western Quebec today. The associated cold front will sweep across Southern Quebec late Friday afternoon. Ahead of this front a few breaks of sun and warming temperatures to near 20C (68F), will act to destabilize the atmosphere. The front will arrive mid to late afternoon, accompanied by a line of heavy showers and thunderstorms. The possibility exists for several of the storms to become severe in eastern Ontario and extreme southern Quebec. Strong winds, hail and heavy rain will be the biggest threat. There is even a slight risk of an isolated tornado, especially south of the St. Lawrence River towards the US border, and into New England.

The temperature will warm in advance of the front, reaching 18 to 21C (65-70F) across the area. As the front clears Montreal, very strong winds will develop in its wake. Wind warnings are in effect for the St. Lawrence Valley, with peak gusts as high as 90km/h possible. The wind will slowly diminish overnight to under 50km/h. On Saturday, we should have clearing skies, along with mild high temperatures of 18C (65F). The wind will remain gusty from the west up to 50km/h.

Water levels continue to slowly rise across Quebec in response to recent rainfall and melting snow. Regions south and east of metro Montreal, including Lake Champlain and the Richelieu River Valley are under flood warnings. A flood watch remains in effect for the rivers surrounding Laval as well as Lac Des Deux-Montagne. According to Hydro Meteo, minor flooding is forecast over the next few days. Vigilance is advised near all bodies of water as they are flowing high, fast and very cold. Minor flooding is also forecast in the Quebec City region, the Mauricie, Lanaudiere, Laurentians and Chaudiere-Appalaches.

Monday, April 30, 2018

Flooding potential on the rise in southern Quebec

Minor flooding was reported along the Milles-Iles River in Laval over the weekend. (Radio Canada)
The miserably cold and wet month of April is finally drawing to a close today. Once the final data is digested, I think we will find that many parts of the country, including Montreal, had one of the coldest April's on record. As we move into May, the hope is warmer air will finally win over here in southern Quebec. First we have to deal with what should be a "normal" flood season, and at least at this point, nothing record breaking like 2017. Hydro Meteo has been monitoring the waterways across the province, and has issued flood watches for many regions. Locally, a flood watch in in effect for the Townships and Laval. While water levels are sharply rising, only minor flooding has been reported to date. Over the weekend, 25 to 50mm of rain was reported across the area. With the ground saturated from earlier precipitation and snowmelt, most of this will runoff directly into rivers and streams. Hydro Meteo issued an update at 6am Monday, reporting significant rises in rivers across the Beauce, Eastern Townships, Quebec City, Mauricie and Lanaudiere. They are reminding residents who live close to waterways or in flood prone areas to remain vigilant.

The upper level low that produced the rainy and cold weekend, will meander into New Hampshire today, and eventually Atlantic Canada by Tuesday. More showers can be expected in Montreal today, with a cool high of 10C (50F). On Tuesday, skies will slowly clear, followed by the warmest surge of air so far this season. Expect a high of 17C (63F) Tuesday, and up to 24C (75F) Wednesday. Unfortunately another frontal system will arrive on Thursday, with more showers and perhaps even the first round of thunderstorms this year. Rainfall amounts may be significant in southern Quebec, adding to the current flood concerns.

Tuesday, April 17, 2018

Record setting storm slowly moving east

Hydro Ottawa poles were snapped in half after 9 hours of freezing rain across the National Capital region. (Hydro Ottawa Photo)
The storm that produced hour upon hour of freezing rain across southern Ontario and Quebec, is slowly releasing its grip on the region. The system was responsible for 9 hours of freezing rain in Montreal, the longest April event ever, dating back to 1953. Between 10 and 20mm of ice fell on the city and suburbs, delaying flights and closing most schools. A peak wind gust of 63km/h occurred at Trudeau Airport. Scattered power outages were also reported, mainly off island to the south and west.

In Ontario, the storm was much worse. Over 80mm of frozen precipitation (rain and ice pellets) fell on Toronto over 24 hours. A peak wind gust of 98km/h occurred at Billy Bishop Airport. In Ottawa and Gatineau, 9 hours of freezing rain deposited 28mm of ice. Power was out to over 60,000 homes in the region, including 44,000 on the Quebec side of the border. The ice snapped hydro poles in half in Ottawa. The Ontario Provincial Police reported hundreds of accidents over the weekend and Monday as a result of the late season storm. The Toronto Blue Jays baseball game was postponed Monday night due to ice falling from the CN Tower onto the roof of Rogers Centre.

The same storm was responsible for heavy snow across the central Great Lakes. Wiarton, Ontario reported 39.6cm of snow, while Green Bay, Wisconsin was hit with their second largest snowstorm ever, 24.2 inches. You have to go back 130 years to March 1-2, 1888 for the largest storm, 29 inches. On the warm side of the storm, widespread severe thunderstorms stretched from Arkansas to the Carolinas. Several tornadoes occurred as well as large hail. Widespread damage was reported, along with multiple injuries and at least four fatalities.