A significant Arctic cold has spread across North America this week. This is in response to the record-breakingly low temperatures in Canada. The winter storm brought heavy snowfall and icy roads conditions to the Mid Atlantic and sub-zero temperatures to the Southeast. The Polar Vortex’s southern lobe shift will send another powerful blast of frigid cold towards the Northeast United States this weekend. Lake Erie and Ontario will see more lake-effect snow.
Many were wondering what was going on with the winter season 2021/22. It arrived this week with a bang. Due to the recent colder than usual weather in Canada, more seasonably cold weather has also spread to the U.S. The winter storm caused havoc on roads in the eastern parts of the country and was frigid for those in the north.
Below, the NASA Worldview satellite shows the impressive amount of snow cover that was created by the first winter storm of 2019. On Jan 4, snow covered a large area from the Appalachians in Washington D.C. to California’s coast, with a sharp edge and no snow cover to its north. Two days later, another storm brought more snow.
The Polar Vortex circulation will cause further changes in the weather patterns across North America. This suggests that we could soon see another Arctic cold wave, targeting the Great Lakes, and the Northeast U.S., which have the coldest temperatures this winter season.
A strong jet stream (high level winds) will be moving across the continent this weekend. It will shift from the west to the northwesterly, allowing for a large pool in west-central Canada of extremely cold weather to move towards the Lakes. However, the cold has already spread to the far northern states, with temperatures in North Dakota and Minnesota hovering around -30F, and wind chills even lower than that at -40F.
Through the weekend, the cold pool will intensify and move from the Upper Midwest to the Great Lakes. With the stronger north-northwesterly flow, further blasts will bring more Arctic weather south towards the Northeast.
The video animation below shows how the Arctic cold temperatures spread from central Canada to New England and New England over the weekend and into next week. You can see how the region is being pushed by a particularly cold air mass.
The warmth that is returning to the Southeast over the weekend could cause severe weather conditions from Saturday night through Sunday. This will be especially true for the low/mid Mississippi Valley, Ohio Valley, and further south-southeast along a moving front. Although instability is minimal at this time severe storms with gusty wind, large hail, and possibly even a tornado are possible again.
Before we dig deeper into the weather pattern developing for the upcoming new cold Arctic blast, let’s first see what is the main driving factor behind these recent pattern changes, known as the Polar Vortex.
THE POLAR VORTEX ABOVE US
The atmosphere is composed of six layers around the Earth. Most of the weather dynamics that affect all life on the planet are found in the lowest two layers, the troposphere, and the stratosphere above them.
The troposphere is the lowest layer and all weather changes are made here. The troposphere layer extends from the Earth’s surface (the sea level) up to 12 km up. Its depth varies from 8 km to almost 20 km. It is the deepest layer above the equator. However, it thickens above the poles.
There is a deeper layer above the troposphere layer. It is called The stratosphere. This stratosphere layer measures approximately 11-50km thick and is very dry. We also find the Ozone Layer in the stratosphere. This layer plays a crucial role in protecting our planet.
The stratosphere has a very important feature that affects the dynamics of our weather: the Polar Vortex. Is an enormous, three-dimensional ring of very powerful winds (about 20-50 km above the Earth’s surface) that surround the North and South poles, strongest during the winter months.
And both the troposphere and the stratosphere layers are crucial for the climate, as the Polar Vortex covers most of the bottom half of the atmosphere, from the Earth’s troposphere up into the stratosphere. The Polar Vortex plays an important role in winter weather at both the high- and mid-latitudes.
Although the vortex spins high over us, it is still directly connected with the lower part of our atmosphere. Because it acts as one large hemispheric circulation, the Polar Vortex shapes our daily weather in many ways.
But how does the Polar Vortex form.
When the calendar turns into autumn months, the polar regions receive much less sunlight over time due to the inclination of the Earth’s axis. The north pole will begin cooling down. Although the poles are cooling down, the atmosphere further south remains warm because it continues to receive more sun and energy from the Sun than the polar regions.
The pressure is also affected by the temperature falling in the polar regions. Similar events occur in the stratosphere layer. Therefore, the temperature differential between the North pole region and the equatorial area increases, and a large lowpressure (cyclonic), circulation develops across polar stratosphere.
When you put it all together, the Polar Vortex acts basically as a large cyclone. It covers the entire north pole down to the regions at mid-latitudes and the same in southern hemisphere.
This chart shows an example of a Polar Vortex that is located at 30 km (18 miles) elevation, which is close the top of stratosphere during winter. We will be looking at charts at 10 mbar when discussing Polar Vortex behavior.
AGAIN BELOW -50 °C IN CANADA, WITH RECORD SNOW ALONG THE PACIFIC NORTHWEST
The weather pattern across North America remains active this week. A deep trough has formed over the western portion of the continent, a strong blocking High being placed across the western parts of the U.S. This increased the westerly jet between them and multiple frontal systems raced into the Pacific Northwest.
This weather pattern is well correlated with the La Nina winters in Canada, and the United States. These are known for heavy precipitation in parts of the continent’s west and northwest, which packs the mountain ranges full of deep snow.
December saw record snowfall in the Sierra Mountains, California. In addition, there was intense snowfall in British Columbia, Canada’s Pacific Northwest. As reported by, parts of British Columbia’s higher terrain saw snowfalls of up to 36-48 hours. Thierry Goose on Twitter..
Callaghan Valley reported snowfall of 199 cm, Whistler Village 104cm. There was 84 cm snow depth at Pemberton and 80cm at Nelson, BC. Lytton, the place we all remember from last summer’s all-time heat record and the destructive fires, was 70 cm on Thursday. Very close to its 1971 record of snow depth of 71cm.
As we discussed in our previous weather forecasts, extreme frigidity has been observed further north. Some parts of Alaska and northwest Canada (Northwest Territories and Yukon) ended up below -50 °C again.
Chicken, Alaska hit the lowest temperature in the United States this winter season 2021/22, it was -51.1 °C this week. The Canadian Yukon state weather stations reported -50.7 °C in Nursery and Ross River with an additional -50.5 °C in Watson Lake and Rabbit Kettle.
Many other stations were just shy above -50 °C in the region as well.
POLAR VORTEX BRINGS THE COLDEST AERIAL OF THE WINTER SESSION 2021/22 FOR THE NORTHEAST
The classic dipole weather pattern that was established in the northern Pacific and western North America at the New Year has allowed a deep upper trough, which has brought frigid cold airmass to western Canada and the Northwest U.S. from early January. The blocking High is strengthening across western North America, with an increase in Arctic air mass to its east.
Normally, high surface pressure develops when there is strong blocking. This will cover most of western Canada as well as the United States. The strong pressure gradient is created by the deep low (cyclone), which lies under the Polar trough’s core to its east. In other words, winds between the two will increase.
The following chart shows a very large pressure difference between western Canada (1041mbar) and eastern Canada (980mbar), which is more than 60mbar. A monster low is also visible in the North Atlantic. It was created by a powerful extratropical storm that produced nearly 930 mbar just a few days before.
These enhanced winds will result in a massive transporting of colder, more frigid Arctic air mass from central Canada between these two large-scale features towards eastern North America. This blast will have eastern Canada and the Northeast U.S. at its core. The flow is pure meridional and the general winds will come directly from the north-northwest.
The Arctic air mass, which is significantly colder than usual, will push east-southeastwards from the central Canada prairies starting Sunday and continuing into the early days of next week. This will cause deep freeze in regions from the Midwest to the Great Lakes to Northeast.
The cold pool, which will be the coldest so far in winter season 2022/22, will be for Ontario, Canada as well as the surrounding areas, Ohio Valley, Appalachians and Northeast U.S.
Daytime temperatures are expected to drop into the teens Sunday afternoon in Chicago. They will then dip even further through Sunday night, and remain in the 10s Monday. It hasn’t been as cold yet this season in this part of the country.
The cold air moves further into the Northeast on Monday. Temperatures will reach the lower 20s and even the upper 10s in New York City on Tuesday. With the nighttime temperatures likely to reach low 10s or even single digits °F for the first time this winter season in Washington, D.C., on Monday and Tuesday next week.
Monday morning will be cold again across the Southeast. The temperature will reach the upper 20s in Mississippi, Alabama, Georgia, and the East Coast. It will be in the mid-10s on the Mid-Atlantic. Similar conditions are expected in the Ohio Valley. Low to mid-10s are possible.
And far colder with sub-zero °F temperatures across northern Iowa and Illinois, eastern North Dakota, Wisconsin, and indeed Minnesota. Even below -10 °F in the morning is locally very likely there. Tuesday will be even colder farther east, with -20 to -30 °F in the morning. That is nearly 25 to 30 °F below normal for southern Ontario.
Meteogram charts are used often to understand how anomalous temperature forecasts are when Arctic eruptions occur. The Meteogram for Boston is attached below. It clearly shows that the Arctic blast triggered by the Polar Vortex high above will be very strong.
While the Northeast U.S. is currently at around slightly below normal temperatures for this time (-10 °F), it is forecast to warm up over the weekend first, in response to a returning advection of much warmer air mass ahead of the new winter storm. But on Monday, a remarkable drop for nearly 50 °F (30 °C) occurs with the Arctic blast emerging from Ontario.
Temperatures will drop to freezing levels, even lower than those experienced in the region this week. The average long-term temperature at 850mbar (approx. 1300-1400 meters above sea level) is, however, around 22 °F (-6 °C) during the first half of January.
Based on the Meteogram forecast above it seems likely that the cold pool won’t be very long-lived. The temperatures should return to near normal levels by mid-next semaine.
MAJOR LAKE-EFFECTS SNOW COULD DEVELOP AROUND THE LAKES ONTARIO & ERIE
The frigid cold air mass that travels from Arctic Canada to the southeast during winter months spreads across the Great Lakes quite often. This effect cools down the lake’s water and leads to freezing. This season so far, this hasn’t happened yet as NOAA reported, as the significant cold to cool down the lakes was missing.
The lakes cover only 4 % of total ice coverage as at January 6th.
Until the ice coverage doesn’t increase, the Arctic cold blasts from Canada are expected to develop the lake-effect snow across the Great Lakes. The higher the potential for lake-effect snowfall, the less ice-free Lakes waters are. If additional Arctic outbreaks occur, the next weeks will likely see more lake-effect snow.
The lake-effect snow is a common phenomenon in the Great Lakes region during winter and late fall. It is caused by cold air moving through the Great Lakes, often from the Canadian Arctic.
Warmth and moisture are transferred to the lower portion of the atmosphere as the cold air mass passes over the unfrozen, always warmer waters of Great Lakes. The air rises, and clouds form, creating a narrow band of heavy snow bands with 3-5 inch snowfall rates.
Wind direction is the key component of the process. It determines which areas will get the strongest lake-effect snow. The most heavy snow falls in narrow bands and squalls. This means that it could be falling in one area, while the sun might be shining just a few miles away in the other direction.
With the recent winter storm, parts of Michigan were submerged under a foot of snow from the lake Michigan.
The wind direction and intensity of the Arctic blast from Canada to the Northeast U.S. could cause a more severe round of lake-effect snow than this week. Due to the arrival of stronger winds and colder temperatures on the lakes Erie, Ontario.
This new blast of frigid northwesterly winds above the Great Lakes will cause severe damage to areas south of Buffalo, NY and Watertown, NY.
Southern Ontario and the areas further east will also see more snow. The snowfall will be between 15-20 inches and 40-60 cm along the entire length of the coastline from New Brunswick and Nova Scotia to Newfoundland, where the winter storm’s core will travel.
DANGEROUS FREEZING RAIN OR ICE COULD BREAK OUT IN PORTIONS OF THE MIDATLANTIC STATES
There is a chance of some icy conditions on Saturday night and Sunday due to the new frontal system moving through the Northeast Saturday evening.
If the right conditions are met, freezing can occur. The layer of freezing air is thin enough that raindrops don’t have time to freeze before they reach ground. Instead of raindrops becoming snowflakes or sleet/graupels, the water freezes on contact with the surface and forms a layer of ice.
A strong warm air mass could temporarily arrive ahead of the Arctic front, and could see some freezing rain fall during the first few hours after precipitation arrives with the new winter storm. This could affect Pittsburgh, Washington, D.C., Philadelphia, New York City, and New York City on Sunday morning.
Even though the amount of freezing rain is not expected to be very large, even minor icing events and freezing rain can still cause dangerous driving conditions. On Wednesday, hundreds of accidents were caused by icy roads.
Images used in this article were provided courtesy of Windy, Pivotalweather, and Wxcharts.
Source: Severe Weather
