Saturday, November 23, 2019

Active weather week ahead for southern Quebec

Another round of light snow is likely on Sunday in Montreal.
The mild weather of Friday has been replaced by a chilly Saturday morning in Montreal. Ile Perrot dropped to -8C (18F) overnight, after a daytime high of 7C (45F) on Friday. This was the warmest day in the last two weeks. The warmth along with gusty southwest winds and 2 to 5mm of rain, helped to melt much of the snow from last weeks storm. Warmer weather will return for the upcoming week before we dip below freezing for an extended period starting late this week.

In the short-term, high pressure will control the weather Saturday across southern Quebec, with a gusty southwest wind up to 40km/h and a daytime high of 2C (36F). The nice weather won't last long as our on and off again Sunday snowfall is back on. Computer models have been having a difficult time locking down the track of low pressure devolving over the lower Mississippi Valley. This system is now forecast to move across interior southern New England on Sunday. The path leaves Montreal on the extreme northwest edge of the precipitation shield. Expect clouds to increase overnight, with light snow or flurries possible on Sunday. Accumulations will be very light in Montreal, perhaps 2cm. Up to 10cm is possible over the Eastern Townships and Beauce, with 15 to 20cm over portions of northern New England. The snow will be wet, with highs near 0C (32F) forecast across the region.

Behind the low pressure, skies will clear out on Monday, with near normal temperatures expected. Another larger storm system is expected by mid-week in southern Quebec and Ontario, along with a mix of rain and snow possible. Behind that storm, very strong winds are likely by Thursday, along with dropping temperatures. 

Monday, November 18, 2019

More wintry precipitation for southern Quebec

Light freezing rain and snow will spread across extreme southern Quebec and New England late Monday and Tuesday. (AccuWeather.com)
After a sunny but very cold weekend, clouds are on the increase to start the week. Montreal had yet another record low this month, on Sunday morning at -13.2C (8.2F), crushing the previous low of -10.1C (14F) set in 1980. Monday should remain dry and cold, with daytime highs reaching -2C (29F) by late in the day. Clouds will begin to thicken this afternoon in response to a coastal storm moving north along the eastern seaboard and a trough moving east from the Great Lakes.

The combination of these two systems will bring a mix of light precipitation into Montreal very late this evening or after midnight. Montreal will remain on the extreme western edge of any major precipitation form the coastal system, but the trough from the Great Lakes will enhance moisture across the city tonight.

Not snow but sand blowing across the roads and ocean water forced the closure of portions of Highway 12 on the Outer Banks of North Carolina over the weekend. A strong coastal storm produced more significant damage and flooding to the same area that was heavily damaged by hurricane Dorian in September. (NCDOT Photo)
A mix of freezing rain and snow is likely in Montreal by midnight, changing to all snow overnight into Tuesday morning, and ending by afternoon. Accumulations will be fairly light in Montreal, but enough to make roads icy and perhaps force some delays at Trudeau Airport. Look for accumulations of 2 to 6cm for Montreal, with up to 10cm possible across the Townships and into the northern New England.

Townships under a freezing rain warning
Before the snow flies, the Eastern Townships can expect 5 to 10mm of freezing rain from late this evening into the overnight hours. Keep this in mind if your travels take you down Highway 10 towards Sherbrooke. Roads will be very icy in those regions. Precipitation amount with this storm system will taper off rapidly as you head north and west of metro Montreal, with very little if any snow expected for the Laurentians and Ottawa Valley.

The balance of the week will feature below normal temperatures, with another chance for snow or rain by late Thursday and Friday.

Thursday, November 14, 2019

From record snow to record cold across Southern Quebec

The City of Montreal is conducting the earliest snow removal operation ever this week after a record breaking 21cm of snow fell on the region. Another shot of light snow is forecast Friday, followed by arctic air for the weekend. (ValleyWeather Photo)
A strong cold front will produce snow squalls across Southern Quebec and eastern Ontario Friday afternoon between 4 and 7pm.

A weak warm front is giving southern Quebec some very light snow late Thursday afternoon. Very little in the way of accumulation can be expected. The good news is that we can expect some warmer temperatures through Friday morning as we head out of the deep freeze for a few hours.

It has been a cold, snowy week, with a record setting 21cm of snow Monday and Tuesday, followed by two days of extremely cold weather for early November. On Tuesday we broke both records for coldest nighttime and daytime temperatures, the low was -10.9C (12F) (-9.4, 1971) with a high of only -4.6C (23.7F). We did the same Wednesday, with a low of -13.5C (8F) (-10.5C, 1986) and a brutally cold high of -7.1C (19F). Windchill reading were in the minus 20s, some of the coldest ever recorded so early in the season in Montreal.

The storm brought the monthly snow total so far to 29.6cm, well above the normal of 20cm, which is for the entire month.

More cold air is on the way. After the brief influx of mild air, a potent arctic boundary will slide across southern Quebec Friday afternoon. The front will be accompanied by scattered snow flurries and squalls. Visibilities may be reduced in sudden bursts of heavy snow during the afternoon hours. The front will bring even colder air to the region than that of earlier in the week. The high on Friday will be 2C (36F) reached during the midday hours. Temperatures will drop rapidly behind the front, down to -15C (5F) by Saturday morning in Montreal.

The weekend will be blustery and cold, but sunny with highs around -5C (23F). We may add two more record lows to the books, Saturday's record is -15C set in 1967 and Sunday's is -10.1C set in 1980. Milder air returns early next week, but temperatures will still remain below the normal high of 5C (41F) for mid November. There will be a chance of rain or snow showers by Tuesday.

Monday, November 11, 2019

Snowfall warning for Montreal

A potent fall storm will spread heavy snow across southern Ontario into southern Quebec to start the week. Anywhere from 15 to 30cm is forecast along the St. Lawrence Valley and points south. A little less, 10-15cm is expected in Ottawa. Record cold will surge into the region behind the storm. (AccuWeather.com)
Snowfall Warning in effect for Montreal

Widespread winter storm warnings are now in effect for a swath of eastern Ontario, southern Quebec and parts of the Northeast US and New England. An arctic boundary has slipped south of Montreal early Monday morning, with much colder air pouring into the region. Temperatures have fallen from a Sunday high of 6C (43F), down to -5C (23F) at 5am Monday. The cold air will remain with us for the balance of the week, with record low temperatures likely by Wednesday morning.

Low pressure developing over the Ohio Valley will lift northeast along the aforementioned arctic front through Tuesday. Moisture will overspread the region late Monday, with snow developing by the afternoon hours. The snow will become heavy overnight into the Tuesday morning commute in Montreal. This is a potent snowstorm for anytime of the season, but especially in early November as the first storm of the season. At this time forecasters are anticipating 15 to 25cm along the St. Lawrence Valley including Montreal, with up to 30cm across the Eastern Townships, northern New York and New England. The snow will spread into eastern Quebec Tuesday, accompanied by 50km/h winds, producing blowing snow.

If you have any travel plans from late today into Tuesday, consider postponing them or allow yourself plenty of extra time. Do yourself and everyone else a favour on the roads, if you have no winter tires on yet, use public transit. Be safe.

Friday, November 08, 2019

First snowstorm of the season possible for Montreal

Strong winds and wet snow are bringing a quick end to the fall foliage season across southern Quebec.
Our first taste of winter weather this season is upon us across southern Quebec, as a strong cold front produced 2 to 10cm of wet snow on Thursday. Most of the snow melted on contact acorss the Island of Montreal, but many off-island suburbs, including Ile Perrot, measured a coating to 2cm of slushy wet snow.

Early Friday morning, a few snow showers moved across Ile Perrot and the Vaudreuil/Dorion region, putting down a quick centimetre of snow. The sudden snow made for a very icy commute, at least until reaching the West Island, where no snow had fallen. Consider this the appetizer to a more potent storm early next week.

Montreal may be looking at our first snowstorm of the season, depending on the exact track of low pressure moving across southern New England early next week. (AccuWeather.com)
First snowstorm of the season?
Friday will be breezy and very cold for early November, with the temperature reaching only -1C (30F), the normal high should be 8C (48F). There is a chance for a few flurries today, as well as gusty northwest winds up to 40km/h, making it feel even colder. On Saturday, high pressure will move in giving Montreal a decent, milder day, with a high near 2C (36F). Sunday will be warmer as a frontal boundary approaches form the west. Expect a few showers around as daytime highs reach 6C (43F). The warmth will be short-lived.

A strong polar front crossing the region late Sunday, will usher in the coldest airmass of the season so far, with temperatures dropping to -10C (14F) by Monday morning. That front will stall across southern New England, setting the stage for Tuesday's potential snowstorm. Low pressure will develop over the Ohio Valley, and move along the front towards southern New England. The storm is forecast to deepen rapidly. Snow will spread into eastern Ontario and southern Quebec late Monday night and persist through Tuesday. Depending on the exact track of the storm and how far south the front settles, we may be looking at a significant snowfall in Montreal. It remains too early for specific amounts, but it should be enough to plow. My current thinking is 10 to 15cm, but this is subject to change.

I will post further updates over the upcoming weekend.