A major winter storm is set to impact Indiana this weekend, bringing the potential for heavy snow, ice, “thundersnow” and dangerously cold temperatures.
The storm will sweep across the state from Saturday into Sunday, following a bitterly cold Arctic air mass already in place.
“This is expected to be an unusually large and severe winter storm,” the National Weather Service said. “Dangerously cold air remains in the forecast for more than half of the U.S. population through the weekend and into early next week.”
The storm will start in Texas and Oklahoma with conditions worsening by Friday evening, according to forecasters. The system is then expected to spread from New Mexico to Virginia on Saturday before pushing into the Northeast on Sunday.
Snow arrives Saturday night
The winter storm will hit in two phases. Light snow may begin Saturday evening as dry, Arctic air initially limits accumulation. The main phase, however, is expected late Saturday night into Sunday as a secondary low moves through the Tennessee Valley.
This will pull in moist Gulf air over the entrenched Arctic air mass, fueling widespread snow across central Indiana.
Dangerously cold conditions
A cold front pushed through Indiana Thursday night, dropping temperatures across the state. Lows Friday morning ranged from near zero in the northwest to the mid-teens in the southeast, with wind chills plunging as low as -20 in some areas. A Cold Weather Advisory remains in effect until 10 a.m. Saturday, urging caution for anyone venturing outdoors, according to the National Weather Service in Indianapolis.
Even after the snow ends, bitter cold will persist. Highs will struggle to reach the mid-teens over the weekend, with wind chills between -10 and -20. Next week, temperatures will remain 10–20 degrees below normal, with lows potentially dropping below zero. Snowpack from the weekend storm could make the cold feel even more intense.
What is ‘thundersnow’?
Thundersnow is essentially a winter thunderstorm, in which lightning and thunder occur during heavy snow instead of rain. It’s rare because the atmosphere has to have a very specific setup to allow strong upward motion in very cold conditions.
To get it, you need strong lift to push air upward, plenty of moisture, colder air aloft and instability in the lower atmosphere so snow-filled clouds can build quickly, the Detroit Free Press previously reported.
“Within any banding across southern Indiana, a few rumbles of thunder will also be possible with models suggesting there may be just a hint of instability,” the National Weather Service in Indianapolis said.
Can you get struck by lightning during thundersnow?
Yes — technically, lightning can occur during thundersnow, but the risk is generally low.
Because thundersnow is usually associated with fast-moving, heavy snow bands, most people aren’t outside long enough to be at serious risk. Snow also dampens the sound and may slightly reduce the danger compared to a typical thunderstorm.
The biggest threat of thundersnow is that it means areas are experiencing very heavy snowfall, which can quickly make roads treacherous and increase the risk of accidents.
Indiana snow totals: Search by address
USA TODAY’s snowfall map shows accumulation over the past 24, 48 and 72 hours, as well as seasonal totals dating back to Oct. 1. Updated multiple times a day, the map lets you toggle between timeframes to see how snow is adding up in your area.
Can’t see the embed? View the file on a separate browser page here.
Winter weather is firmly in place across Indiana, where lake-effect snow in the northern portion of the state can create sharp differences in accumulation. One neighborhood may see just a few inches, while areas a few miles away — especially closer to Lake Michigan — could pick up a foot of snow.
With multiple rounds of lake-effect snow and Arctic air possible over the next couple days, knowing your exact snowfall total can help with travel plans, school decisions and clearing driveways and roofs.
Enter your address below to see snowfall totals for your location and a map of nearby measurements.
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Brandi D. Addison covers weather across the United States as the Weather Connect Reporter for the USA TODAY Network. She can be reached at baddison@gannett.com. Find her on Facebook here.
This article originally appeared on Indianapolis Star: Thundersnow could be coming to Indiana with winter storm. What is it?
Reporting by Brandi D. Addison, USA TODAY NETWORK / Indianapolis Star
USA TODAY Network via Reuters Connect
