By Haley Brink and Jennifer Gray, CNN Meteorologists
Despite the calendar saying it’s mid-November, winter has arrived across the Lower 48 and could stick around through Thanksgiving next week.
This week, snow flurries and an arctic chill are in the air for millions across the nation. A low-pressure system across the Southwest will sweep across the central Plains today, bringing with it rain and snow showers.
It will be the first notable winter weather event of the season for most in the region, according to the Weather Prediction Center.
“While uncertainty remains regarding the location of the heaviest axis of snow, the potential exists for snowfall totals of 3 to 6 inches across west-central Oklahoma,” the prediction center said. “Light snow totals are also possible across southern Kansas and the Texas panhandle.”
Winter weather alerts are in place across the region, including Kansas City, Oklahoma City, Wichita in Kansas, Amarillo in Texas, and Fort Smith in Arkansas. The falling snow will lead to reduced visibility and hazardous driving conditions today.
The system will push east this week and with well-below-normal temperatures already in place. Ice, sleet, and snow showers are possible across the Midwest and into interior parts of the Northeast Tuesday and Wednesday.
Coastal areas of the mid-Atlantic and Northeast are currently forecast to see a cold rain, as temperatures are expected to remain just above freezing.
If you haven’t already, you may want to pull out your winter coats and sweaters. More than 225 million people across the Lower 48 will experience temperatures at or below freezing this week, which is about 70 percent of the US population.
The cold temperatures are already in place with readings running 10 to 20 degrees below normal for many, highs below freezing across the northern Plains and upper Midwest, and highs only in the 50s across the South.
The Central Plains are seeing the coldest temperatures compared to average with highs 25 to 30 degrees below normal today.
Only Florida is escaping the early winter chill, but even the Sunshine State will get in on the cooler air later this week.
By Thursday, another bout of arctic air will surge south from Montana into the central Plains and Midwest by Friday, reinforcing cold temperatures of 25 to 35 degrees below normal.
If the cold air helps you get into the holiday spirit, you are in luck! This arctic air is expected to stick around for much of the nation through Thanksgiving week. The bull’s-eye of the arctic air next week will stretch across the Great Lakes, south to the Tennessee River Valley.
We will have more details on how cold your Thanksgiving week could be and any travel hazards to be prepared for in next Monday’s Weather Brief.
In the meantime, now that cold and wintry weather has begun, we wanted to share with you a few weather terms you are likely to hear a lot about this season. And it might give you a little something to impress your friends with your weather knowledge.
It is not a new term, but the polar vortex is always present and always has been.
It’s a large area of low pressure and cold air surrounding the Earth’s North and South poles and is located tens of thousands of feet into the atmosphere. This counterclockwise flow of air helps keep the very cold air near the poles.
“Many times, during winter in the Northern Hemisphere, the polar vortex will expand, sending cold air southward with the jet stream,” the National Weather Service explained. “This occurs fairly regularly during wintertime and is often associated with large outbreaks of Arctic air in the United States.”
February 2021 was a classic example of the polar vortex weakening, sending a surge of Arctic air very far south. One week in February, every state in the US experienced temperatures below freezing.
Sometimes the cold air will dive down and meet warm, moist air traveling north from the Gulf and Atlantic, and you end up with a Nor’easter.
If you are one of our friends in the Northeast, you are no stranger to nor’easters, which are storms which travel north along the East Coast. It gets its name because winds over coastal areas are generally out of the northeast.
“They nearly always bring precipitation in the form of heavy rain or snow, as well as winds of gale force, rough seas, and, occasionally, coastal flooding to the affected regions,” the weather service noted. “The heavily populated region between Washington, DC, Philadelphia, New York and Boston, the ‘I-95 Corridor,’ is especially impacted by nor’easters.”
Nor’easters can cripple this region of the country by snarling traffic, bringing flights to a halt and sometimes resulting in power outages.
If the nor’easter strengthens rapidly, we can end up with a bomb cyclone.
A bomb cyclone is a rapidly strengthening storm which drops 24 millibars (a unit of pressure) in 24 hours. It’s as simple as that. Nothing explodes, but they can be dangerous.
We have seen bomb cyclones affect the Northeast as well as West Coast with hurricane-like furry.
Just last year, this West Coast bomb cyclone brought hurricane-force winds, 20-foot seas, rain and snow to a huge chunk of the West.
Winter weather is interesting, no matter how you categorize it. But if Mother Nature throws a punch during the winter, you might be lucky enough to hear thundersnow!
While winter thunderstorms are far less common than summer thunderstorms, they can occur.
“Thundersnow occurs where there is relatively strong instability and abundant moisture above the surface of the Earth, such as above a warm front,” the National Oceanic and Atmospheric Administration said. “The ingredients that create thundersnow are similar to the dynamics of a typical thunderstorm — moisture, instability, and a lifting mechanism.”
We’ve heard thundersnow several times while covering big snow events, and it sounds different from summertime thunder. The heavy snowfall can muffle the sound of the thunder, making it sound more like a slow rumble and not as booming.
And yes, thundersnow does indicate lightning is in your proximity, so treat it the same as you would a thunderstorm and seek shelter.
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