Thursday, April 20, 2017

More rain equals more flooding for southern Quebec

Flooding along the Ottawa River at Pointe Fortune, Quebec. (Traversier le Passeur Photo) 
Flooding concerns continue to mount tonight across southern Quebec and eastern Ontario, with more rain in the forecast. A state of emergency has been declared in Rigaud, northwest of Montreal, as a result of flooding from the Ottawa and Rigaud Rivers. Melting snow upstream, combined with heavy rain during the month of April, have pushed the Ottawa River and its tributaries to near record levels. In Rigaud, evacuations have been ordered, with numerous roads impassable. All that water continues to flow towards Montreal and Laval. Water levels along the rivers surrounding Montreal, as well as on Lake of Two Mountains and Lac Saint Louis, are producing flooding. Greatest concern at this time are low-lying areas in Laval, as well as Sainte-Anne-de-Bellevue, Pierrefonds, Senneville and Ile Bizard. Minor flooding is also occurring along the shoreline of L'Ile Perrot. The Town of Hudson is also watching Lake of Two Mountains which is expected to rise by several centimetres into this weekend. Sandbags are being made available by that municipality.

Laval communities are on high alert as flooding continues along the Milles Iles and Riviere des Prairies. (Radio Canada Photo)
Southeast of Montreal, Lake Champlain reached flood stage of 100 feet on Tuesday, but has since lowered slightly. Minor flooding is occurring along shore front communities in upstate New York and Vermont, northward into the Richelieu Valley of Quebec. More rain and isolated thunderstorms are in the forecast as low pressure moves from the Great Lakes into eastern Ontario on Friday. Rain will develop early Friday and taper of Saturday. Another 15-20mm is possible for the entire region.

Monday, April 17, 2017

Flood watch posted across southern Quebec

Lac St-Louis lapping at the shoreline of L'Ile Perrot early Monday morning. Minor flooding is occurring around the lake, as water levels continue to slowly rise. (ValleyWeather Photo)
Above-normal precipitation, along with seasonal snow melt, has prompted authorities to issue a flood watch for southern Quebec, including metro Montreal. According to Quebec water watchdog Hydro Meteo, several rivers have or will exceed flood stage this week. They include, but are not limited to, the Ottawa, St. Lawrence, Mille Iles and Riviere des Prairies around Montreal and Laval. The Richelieu River, southeast of Montreal, is also on the rise, as is Lake Champlain, which is expected to approach 100 feet this week. The normal level for the lake is either side of 95 feet. North of Montreal, flooding has already occurred in Rawdon, along the Ouareau River. In Mirabel, 22 homes have been evacuated.

Moderate flooding is occurring north of Montreal in Rawdon, Val Morin, Val David and Mirabel, shown above. (CBC Photo)
Minor flooding is anticipated along river roads in and around the entire region. Rivers and lakes are swollen, and in some cases, with rapid and erratic water levels and flows. Caution is advised near any body of water. Precipitation amounts in southern Quebec over the last two months have been well above normal values. In March, Montreal measured 114.6mm of precipitation at Trudeau Airport. The 30-year average is 69.1mm. To date in April, over 114mm of precipitation has fallen, with only half the month gone. April usually records 82.2mm for the entire month. A break in the rain is expected on Tuesday, before another series of storms arrives for Wednesday through Friday. Low pressure is forecast to approach New England Wednesday, spreading rain into southern Quebec. Another 25mm is expected. Additional flooding is likely.

Monday, April 10, 2017

A month's worth of rain in four days in Montreal

Just one of the hundreds of Quebec homes impacted by heavy rain and flooding over the weekend. Hardest hit were Sainte-Thérèse and Mirabel, but numerous other communities were impacted as well. (CTV News)
The weather across southern Quebec has gone from winter to summer in less than a week. That is fantastic, as long as you are not one of the hundreds of residents affected by flooding. The combination of very heavy rain, melting snow and ice jams has created moderate to major flooding in several regions of the province.

Trudeau Airport recorded 84.4mm of rain between April 4 and 7. The long-term normal rainfall for the entire month of April is 67.7mm. The heavy rainfall, combined with the snow melt from March storms, produced both sewer backup and river flooding. Hundreds of Quebec homes have had basements inundated with water and mud. Hardest hit to date have been the lower Laurentians, including Mirabel and Sainte-Thérèse. Numerous homes have also received flooding in Two Mountains and parts of Laval, along Lake of Two Mountains. There has even been flooding reported on the Island of Montreal. Currently, Lac St-Louis is running at record levels, 22.13 metres as of April 4th. Over the weekend, the Ottawa River was almost level with Avenue St-Charles in Vaudreuil.

Flooding north of Montreal (Global News)

Most of Quebec is currently under a flood watch as more rain is forecast. As I am writing this blog, temperatures have soared to near record highs in southern Quebec. L'Ile Perrot reached 27C (81F) at 1pm Monday, while the airport is slightly cooler at 25C (77F). The record high for the date is 26.1C (79F) set in 1945. While most of the snow is gone in metro Montreal, there is still plenty upstream, along the Ottawa River Valley and into the Laurentians. Rapid snow melt will continue to be a problem, adding to the high water levels. Vigilance is recommended near any rivers or lakes, through at least the end of the month. Cooler air is on the way for the balance of the week. Seasonable daytime highs near 10C (50F) are expected. However, rain is forecast as well. A cold front will produce scattered showers and thunderstorms tonight and Tuesday. Another 10 to 15mm of rain is expected.

Thursday, April 06, 2017

Another round of heavy rain for southern Quebec and Ontario

A strong storm system will produce more heavy rain across southern Quebec over the next 24 to 36 hours. (AccuWeather)
Strengthening low pressure will slowly move from the Ohio Valley into New York State today. This storm will be responsible for a wide variety of severe weather, from the southern US northward into the Great Lakes, as well as Ontario and Quebec. Environment Canada has posted a heavy rainfall warning for southern Quebec, as well as most of southern and eastern Ontario. Flood watches are in effect across New York and New England. Southern Quebec and eastern Ontario can expect heavy rain once again, starting by the noon hour today and continuing into the overnight hours. As colder air wraps around the back end of the storm, the rain will change to snow west of Ottawa and across central Ontario tonight. In Montreal, we are expecting 25 to 40mm of rain. This amount is in addition to the 35mm the city received on Tuesday. Minor flooding was reported already, with the new rain adding to the sharp rises on rivers and streams. Temperatures will remain chilly, in the 3 to 5C (38 to 41F) range through Saturday. Winds will become rather strong and gusty in the St. Lawrence Valley, up to 60km/h.

The expected track of this low pressure would have produced a major snowstorm last month, but enough warm air is in place to guarantee rain for Montreal. Further north, heavy wet snow is expected. The same storm system produced widespread severe weather across Indiana and Georgia, stretching into the Carolina's Wednesday and today. Multiple tornadoes produced damage and injuries. More strong thunderstorms are expected today.

Behind the storm, a surge of warm air will arrive by Monday in Quebec and Ontario. Temperatures are expected to rise into the upper teens in Montreal.

Monday, April 03, 2017

More springlike with heavy rain forecast for Montreal

Spring flooding, such as that shown above in Huntigdon in 2014, is possible this week across southern Quebec. (CBC Photo)
Environment Canada has issued heavy rainfall warnings for portions of the St. Lawrence Valley. The first of two potent low pressure areas will begin to impact southern Quebec on Tuesday. Steady rain should move into Montreal early Tuesday and continue into Wednesday. Expect between 25 and 37mm (1 to 1.50 inches) of rain. The rain will cause sharp rises in area rivers and streams and could lead to some flooding. At this time no flood watches or warnings are in effect. North of Montreal, a period of freezing rain is possible early Tuesday. Closer to Quebec City and points north and east, snow is likely before a changeover to mixed precipitation and eventually rain. Icy travel is expected in those regions. Temperatures in Montreal will remain above freezing Tuesday, with lows near 2C (36F) and daytime highs of 5C (41F).

After a brief respite Wednesday afternoon, a stronger storm will move from the lower Mississippi Valley towards New York State. This system will deliver another 25 to 50mm (1 to 2 inches) of rain to southern Quebec through Friday. The rain will begin early Thursday morning and become heavy at times. The combination of heavy rain, melting snow and ice breaking up on rivers and streams, will elevate the flood risk once again as we head towards the end of the week. Monitor river levels closely, especially if you live in flood prone areas of southern Quebec.

Thursday, March 30, 2017

More snow forecast for southern Quebec and Ontario

A late winter storm will provide plenty of sloppy travel across the Northeast US, southern Quebec, and eastern Ontario, from Friday into early Saturday. (AccuWeather)
Stubborn low pressure over eastern Canada has maintained a cool northerly flow for most of this week in Montreal. Combined with low clouds and fog, it has not been a very pleasant stretch of weather. Sunshine will make a brief appearance Thursday as high pressure crests over the area. This will provide us with a near perfect early spring day, expect a high temperature near 7C (45F) and light winds.

Late Winter Storm
Now the bad news, the good weather will be very short-lived. Low pressure is forecast to develop today and strengthen as it move across the Ohio Valley and southern New England on Friday. A plume of moisture arrives Friday in the form of snow mixed with a cold rain. All precipitation goes over to wet snow late Friday evening in Montreal, becoming heavy at times. Forecast accumulations appear to be in the 10 to 20cm range, the highest in northern New York, Vermont and the Eastern Townships. Montreal and Ottawa should have close to 10cm by Saturday morning. The storm will be terrain driven, with the highest accumulations expected in the hills and mountains, lowest amounts on the valley floors. Some mountain locations in southern New England may see up to 30cm (1 foot) of heavy wet snow. The weight of the snow may pose a problem to power lines and trees depending on how much you receive. The temperature in Montreal will be 3C (38F) Friday, but drop once the snow starts to around the freezing point. Precipitation should end Saturday, along with partial clearing and milder temperatures. It should all be a bad memory by Sunday, with sunshine expected and a high of 10C (50F) in Montreal.

Sunday, March 26, 2017

Warmer weather returns - but first freezing rain for Montreal

Not very spring-like, but still beautiful on L'Ile Perrot and across southern Quebec early Saturday morning. This was the result of a surprise 10-15cm snowfall on Friday. (ValeyWX Photo)
Environment Canada has posted a freezing rain warning for southern Quebec and eastern Ontario. Low pressure over the southern US will push a warm front north towards the Canadian border on Monday. This is the same front that delivered a surprise, heavy snowfall on Friday to both Montreal and Ottawa. Most forecasters were expecting a limited snowfall of perhaps 2-4cm. Montreal received 11.4cm of snow, breaking the daily record for March 24 of 8.6cm established in 1991. Ottawa received 22cm of snow, smashing the 50 year old daily record of 6.4cm set in 1966.

The aforementioned warm front returns today, pushing an area of precipitation ahead of it this afternoon, into the colder air at the surface here in Montreal. A period of freezing rain is forecast from late this evening into the overnight hours. Temperatures are cold this morning, -7C (19F) in Montreal, but will warm above freezing overnight. By Monday, plain rain is expected with improving travel conditions, and a high of 2C (36F). Before the temperature warms however, a decent 2 to 10mm of ice is expected across the region. Travel will be impacted from late this afternoon into the wee hours of Monday morning. 

The same icy conditions are expected in northern New York and New England. The balance of the week will be much milder, with daytime highs approaching 10C (50F). Perhaps spring has finally sprung...perhaps.