Tag: Ice Pellets

Ontario

How a Major Blizzard Stateside Will Impact Ontario

An area of low-pressure sliding out of Colorado will undergo explosive intensification through the day Wednesday. This will be an blockbuster blizzard for portions of the Upper Midwest including South Dakota & Minnesota. 40-60cm+ of snow concurrent with 70-90km/h winds will cripple the region.

BLIZZARD WEAKENS AS IT MOVES INTO NORTHWESTERN ONTARIO

The explosive Colorado Low that will cripple South Dakota, will thankfully be weakening as it approaches Ontario. Snow will move into the Thunder Bay, Nipigon, Atikokan, Upsala area before midnight Thursday. Accumulating snow will combine with gusty winds between 40-55km/h, through Thursday night and Friday. It will be a good day to stay home and off the roads if you can.

Moderate to heavy snow transitioning to rain across Northeastern Ontario. Northwestern Ontario sees all snow from this system. Click to navigate the map and find your region.

Wawa to Timmins will see more ice pellets and wet snow, than rain. A transition to rain showers is expected throughout Friday Afternoon.

Kapuskasing to Hearst will remain as snow, where 15-20cm is expected to fall.

SOUTHERN ONTARIO IMPACTS

Strong wind, a surge of warmer air and rainfall will be the story across Southern Ontario Friday. A cool and partly-cloudy day Thursday, with patchy mixed precipitation. Largely confined to Southwestern Ontario.

Strong wind anticipated across Southwestern Ontario Friday morning. Strong Southeasterly gusts between 70-80km/h is expected north of Lake Erie and East of Lake Huron.

Temperatures in the afternoon will spike into the double digits across Southern Ontario. The Nations Capital Region will see the temperature climb near 9c. The trade-off will be a lousy day with occasional rain or showers Thursday. There is even a risk for localized thunderstorms early in the day Friday.

Ontario

[UPDATED] Freezing Rain & Power Outage Risk Across Portions…

A risk of freezing rain supersedes an early February warm-up. A temperature roller coaster with a risk of freezing rain will be the story this week across Southwestern Ontario.

Rainfall and above seasonal temperatures are the story this evening into the overnight. Rainfall ends before morning, with temperatures falling throughout the day.

Be mindful around streams and creeks Tuesday morning. As well as, on roadways, where standing water could lead to hydroplaning. Rainfall and snow-melt will lead to higher water levels. Stay tuned to your local Conservation Authority for the latest information.

A freezing rain risk develops by Wednesday morning. This may be an extended period of freezing drizzle & freezing rain for locales north of Lake Erie, including the 401/402 corridor. Local freezing rain accretion may approach or exceed 15mm. Ice pellets and patchy freezing drizzle will be the story for the rest of Southwestern and Central Ontario.

Projected Freezing rain between Wednesday & Thursday AM. Freezing rain will also track east of Lake Huron. Hamilton-Brantford will be at risk for 15mm of ice accretion and power outages.

There will be two waves of precipitation. The second translates across the region Thursday along a developing low-pressure system. There is some uncertainty in regards to the evolution of this system. Current model guidance suggests a northerly track, leading to a surge in temperatures (above freezing) across Southern Ontario, Thursday. This would be a big snow maker across Northern Ontario & Quebec.

Projected Power Outages Through Wednesday Evening.

Sporadic power outages are anticipated across portions of Southwestern Ontario. A stiff northeasterly wind (aiding in low-level cold delivery), will be enhanced over Lake Ontario. Bringing wind gusts to 40km/h downwind of the lake. Sporadic power outages will begin throughout the evening. Peaking between 8pm-12am Wednesday. An extended period of freezing drizzle will succeed the initial wave of convective-driven freezing rain. For regions East of the Escarpment, through South Central Ontario & the Northern GTA this will be a primarily ice pellet event. Briefly beginning as snow, especially stretching from the Bruce Peninsula through Northern sections of Central Ontario.

Charge those devices! And stay tuned.

Ontario

[UPDATED] – Historic Weekend Ice-Storm and Strong Wind Gusts…


A strengthening, and ultimately a strong low pressure system from the Central Plains of the USA will approach Ontario and Quebec this weekend and stall as strong High Pressure in Northern Canada will force the low to become incredibly stagnant over the regions. There will be breaks in the precipitation at times [and a couple pulses of significant moisture, especially Sunday], but overall, the ‘quantitative precipitation forecast (QPF)’, or measurable total precipitation will be high from Saturday through Monday.

It is important to note that this storm will have EXTREMELY tight gradients between precipitation types and amounts (and hence, temperature). One region to the next in as little as 20 or 30 kilometers could receive drastically different amounts of snow, ice-pellets, and/or freezing rain. The difference between -1 and +1 could pose significant changes in traveling conditions for residents across ON/QC.

Importantly, regions who receive ice-pellets should note that the water content for snow and ice-pellets are drastically different. While snow is, on average, 10:1, ice-pellets are typically 2 or 3:1. This means, that 20-30mm worth of ice-pellets will “look” drastically different than 20-30cm of snow. On our forecast map, ice precipitation totals are displayed in mm. Please note that this is the equivalent amount of moisture that will fall as ice pellets. If 25mm falls – 75mm worth of ice pellets would accumulate; 3:1 ratio.

What to Expect

1) Heaviest Snow Region: Colder air will invade much of this region leading to mostly exclusively heavy snow. Some snow will occur Saturday/Monday; significant snow through Sunday.

2) Mostly Heavy Snow Region: Colder air will also invade much of this region. Most impacts through Sunday and residual on Monday.

3) DRY-SLOT. Some of: Snow/Ice/Rain Region: There appears to be somewhat of a dry-slot that will force itself within the large pulses of moisture – one across Northern Ontario – one across Southern Ontario. This dry-slot appears to encompass a large swath. However, while impacts will be reduced, they will still exist. This region can expect between 5-10cm of snow (locally up to 15cm), and a mixture of 5-10mm of ice precipitation in the form of ice and/or ice-pellets. Regions around Parry Sound and east will likely receive more freezing rain (than snow), while regions around Ottawa will receive more snow (than ice). It is possible, that regions just south of Ottawa could receive ~15cm. Ottawa itself is likely to receive closer to ~10cm and brief ice or ice pellets.

4) Wintry Mix Zone Region: Much of this region will receive snow, ice-pellets and light freezing rain. The colder air appears to be digging in more and more, and as such, freezing rain will likely no longer be a large threat (but will still lightly mix within at times). Regions such as Wiarton, Owen Sound, Barrie, Orillia, Midland, Collingwood, Meaford, Bracebridge, Gravenhurst, Peterborough, Bancroft and Muskoka are more likely to receive snow (>15cm); ice pellets (>15mm) for regions a little south of a line from Owen Sound east to Barrie and due east to Brockville.

5) Ice-Pellets [possibly Snow] and Ice Region #1: The Northern Lake Ontario shoreline is expected to receive a mixture of heavy ice-pellets and some ice. There is some potential that snow alongside ice-pellets could fall thereby reducing ice-pellet amount and increasing snowfall amounts in the 10-20cm range (lesser snow and more ice-pellets closer to the Western and Central Lake Ontario shoreline, such as: Ajax, Oshawa and Pickering; more ice for Eastern Lake Ontario sections such as Kingston and Brockville).

6) Ice Pellets [possibly Snow] and Ice Region #2: This region in Southern Ontario is expected to receive a mixture of ice-pellets and ice. There is some potential that snow alongside ice-pellets could fall thereby reducing ice-pellet amount and increasing snowfall amounts in the 5-15cm range (the lesser snow and more ice-pellets will be towards the Lake Huron shore-line, such as Goderich – higher amounts of snow for regions closer to Owen Sound and Barrie, than regions further away).

7) Highest ICE STORM Threat Region: This region continues to represent the highest potential for significant ice. Widespread 25mm is likely with some evidence suggesting 30mm or more by late Sunday.

8) High ICE STORM Threat Region: This region continues to represent a reasonably high potential for significant ice. Widespread 20mm is likely with some evidence suggesting closer to 25mm.

9) Moderate ICE STORM Threat Region: This region now shows some risk of an ice-storm. Early rainfall on Saturday may keep the ground warm enough where impacts for much of Saturday will be somewhat limited until early to mid evening. Impacts however by the end of Sunday could still pose a significant impact/risk. Depending on the cold air, it is possible this region may extend due west along the 402 through Komoka, Strathroy, Watford, Petrolia and Sarnia.

10) Risk of Non-Severe Thundershowers Region: Extreme SW Ontario is expected to receive mostly rain. Non-severe thundershowers are indeed also possible early Saturday. Expect a heavy and soaking rain. Very brief or slight ice is possible (1-3mm).

11) Critical Zone – Heavy Rain and Ice vs. Location Region: The Toronto region represents one of the hardest forecasts in this entire ‘storm’. Toronto will be extremely location dependent. People who live near the lake-shore will likely experience mostly rain with negligible amounts of ice. However, within the city there could be roughly 5-10mm of ice, and regions outside the city, 10mm+ of ice is possible.

This is due to a strong easterly and stiff (but shallow) wind off Lake Ontario which will create a small plume of far less freezing rain than surrounding counterparts.

[UPDATED] Which Regions are most likely to be Hit the Hardest from Ice? How Much?

25mm or more of accretion is expected.

St. Thomas
London,
Woodstock
St. Mary’s
Ingersoll
Brantford
Port Dover
Tilsonburg
Stratford
Mitchell

[UPDATED] In Southern Ontario which Regions are most likely to Receive the most Snow? How much?

Snowfall of 20-30cm, locally higher.

Owen Sound
Wiarton
Barrie
Orillia
Collingwood
Meaford
Gravenhurst
Minden
Haliburton
Angus
Bancroft
Whitney

City of Toronto – A ‘Tough Call’

For right in the City of Toronto, it is expected that a strong easterly wind will result in a slightly milder air-mass at the surface. As such, we at TCW believe the city itself should escape some of the ice, in comparison to regions further (although slightly outside) the city.

Therefore, we expect Toronto to receive mostly rain [especially the lake-shore] – perhaps still some freezing rain at times, late Saturday into early Sunday — however, rain will likely infiltrate before and after any freezing rain, thereby melting most of the ice that happens to fall and/or stick to the surrounding environment.

Nearby cities such as Mississauga, Brampton, Oakville, Ajax, Bowmanville, etc, are expected to see some ice. The closer one is directly to Toronto itself, the greater chance of more rain, and less ice. Once you reach roughly 10-15km outside of Toronto however, it is expected ice will be of concern.

Notice: QEW Region (Niagara, St. Catharines. Welland, etc)

This region is also an important place of interest due to again, slight warming from Lake Erie and Lake Ontario. This means regions very close to Lake Ontario and Lake Erie (within 10km of the shorelines or less) will receive 15-20% less ice than regions further away. However, irrespective of proximity towards the lake-shores, it is expected still, significant icing will occur.

How Bad Will This “Ice-Storm” Be?

This ice-storm has the potential to be significant. While it may be slightly less significant than if this event occurred in the typical winter months (due to stronger April diurnal heating in addition to a wet ground from late Fri to early Sat), it will still pose a significant threat to travel, trees and could lead to widespread and significant power-outages.

When Will Most of the Icing Occur?

Regardless of location, even regions who receive lesser ice accretions, the most widepsread, and heaviest icing will occur between the late morning or early to mid afternoon hours on Saturday, through Sunday. Even more specifically, most of the heaviest freezing rain will occur early to mid Sunday morning.

Monday Temperatures

Many regions are expected to transition to rain of some magnitude during Monday (slowly beginning later on Sunday).

Northern Ontario is expected to continue with further snow however, therefore temperatures although may climb above 0C, relatively humidity will be quite low and moisture will be quite high, therefore, regions will continue with snow.

On Monday Night, snow (3-7cm) may usher in towards the highlands and regions such as Shelburne and north of Toronto as cooler air returns.

Watch for widespread gusty winds for many regions up to 80km/h.

Please stay tuned, as we at TCW are monitoring this situation attentively.

Drive safe and always be alert during hazardous conditions.

For hourly and live storm updates around the clock, follow us on Twitter.
https://twitter.com/TransCANWeather