Severe Thunderstorms Head to Midwest, South, and Northeast

Josh Edelson/AFP/Getty Images
Josh Edelson/AFP/Getty Images

A widespread outbreak of severe thunderstorms could make for a tense couple of nights to welcome the unofficial start of spring in the Midwest and parts of the East Coast. Forecasters expect dangerous thunderstorms to develop in the Midwest on Tuesday night, February 28, and slowly make their way east before another round of storms flares up late in the day on Wednesday. Tornadoes, damaging winds, and large hail are all possible, though the greatest threat that communities face could be all of those hazards occurring at night.

This severe weather outbreak will follow a classic pattern that’s common during the spring. The fuse that will set off the atmospheric fireworks is a developing low-pressure system over the Plains that has made its way toward the Great Lakes today. Winds circulating around the low are funneling warm, unstable air north from the Gulf of Mexico, bathing the Mississippi and Ohio River Valleys with unseasonably muggy air. This soupy air serves as the fuel to power thunderstorms triggered by the lift from the low-pressure system and its fronts. Making matters worse is that strong winds through the atmosphere will help those thunderstorms turn severe. As of press time, tornado watches have been issued for Illinois and parts of Iowa, Missouri, and Arkansas.


The Storm Prediction Center’s forecast for severe thunderstorms on Tuesday, February 28, 2017. Warmer colors indicate a greater risk for severe weather. Image Credit: Storm Prediction Center

 
The severe thunderstorms will thump communities in several rounds, with each round carrying its own safety risks. The latest forecast from the Storm Prediction Center calls for the worst weather to unfold from Arkansas to Ohio during the evening and nighttime hours on Tuesday. Thunderstorms are bubbling up on the western part of the risk area and working their way east. Tornadoes are possible, and some could be on the stronger side. As the evening wears on and the cold front draws closer, these discrete thunderstorms should merge into a squall line, at which point the main hazard will transition to damaging straight-line winds. Small tornadoes are possible along the leading edge of the squall line.


The Storm Prediction Center’s forecast for severe thunderstorms on Wednesday, March 1, 2017. Warmer colors indicate a greater risk for severe weather. Image Credit: Storm Prediction Center

 
Wednesday’s storm threat looks a little more straightforward than what we’re likely to see on Tuesday night, but it’s no less dangerous. Meteorologists expect more squall lines to form along the cold front as it approaches the Ohio Valley and the Appalachian Mountains on Wednesday evening. The lines of storms could produce damaging winds and a few tornadoes as they sweep eastward. It remains to be seen how strong the storms will be once they cross the mountains—the steep hills and valleys often take the oomph out of approaching storms, but they could regenerate once they cross back over flatter terrain.

When we talk about severe thunderstorms, the term “damaging winds” refers to thunderstorm wind gusts that reach 58 mph or stronger, and “large hail” is a hailstone the size of a quarter or larger. We consider tornadoes “strong” when they cause damage that’s rated EF-2 or higher on the Enhanced Fujita Scale. It’s important to remember that damaging wind gusts can easily cause as much damage as a tornado, but over a much larger area.

Severe thunderstorms are dangerous any time of the day, but they can pose a greater threat to your life when they occur at night. You’re less likely to receive life-saving severe weather warnings at night when you’re asleep than you are during the day when you’re more aware of your surroundings. If you live anywhere expecting severe weather, make sure you have a way to be notified of hazardous weather at night. Most smartphones have a wireless emergency alert (WEA) feature that sounds an annoying (but useful) tone that could wake even the deepest sleeper when a warning is issued for your current location. Thanks to the widespread use of smartphones, wireless emergency alerts have saved countless lives in the past couple of years.

But, there’s a catch. In order for wireless emergency alerts to work, your cell phone has to be charged, and it needs to be able to receive a signal. It’s always a good idea to have a couple of backups just in case. A NOAA Weather Radio is a smart albeit slightly outdated investment to make. These devices are like smoke detectors for the weather. You can program a county’s unique code into the device and set it to sound a loud tone when a watch or warning is issued for the location(s) of your choosing. If all else fails, you can also leave your television or radio on loud enough that you can hear emergency alert tones if a warning is issued for your area.

Storm Leaves Homes Along Lake Erie Covered in Up To Three Feet of Ice

Houses along Lake Erie's shoreline were pummeled with sheets of icy water during a storm last week.
Houses along Lake Erie's shoreline were pummeled with sheets of icy water during a storm last week.
John Normile/Getty Images

This past weekend, lakeside residents of Hamburg, New York, awoke to find their neighborhood transformed into a full-scale replica of Frozen’s ice-covered kingdom, Arendelle.

According to CNN, gale force winds produced giant waves that sprayed the houses along Lake Erie with sheets of water for two days straight, covering them in layers of ice up to three feet thick.

“It looks fake, it looks surreal,” Hamburg resident Ed Mis told CNN. “It’s dark on the inside of my house. It can be a little eerie, a little frightening.”

While the homeowners are anxious for the ice to melt, they’re also concerned about what could happen when it does.

“We’re worried about the integrity, of structure failure when it starts to melt, because of the weight on the roof,” Mis said.

He added that this is the worst ice coating he’s seen since he moved to the area eight years ago—but it’s not because they’ve had a particularly harsh winter. In fact, just the opposite is true. According to The Detroit News, warm winter temperatures have caused ice cover on the Great Lakes to drop from 67 percent in 2019 to less than 20 percent this year.

“Lake Erie typically has significant ice cover by this time of the year, and that protects the shoreline from these battering storms,” The Weather Channel’s winter weather expert Tom Niziol explained in a video.

The phenomenon has created another unforeseen issue for Hamburg’s coast, too: Tourism. The local police department posted a message on Facebook on Sunday, March 1, asking people to keep off both the “extremely unsafe and unstable” ice and people's private property.

[h/t CNN]

What is Lake-Effect Snow?

Tainar/iStock via Getty Images
Tainar/iStock via Getty Images

As you probably guessed, you need a lake to experience lake-effect snow. The primary factor in creating lake-effect snow is a temperature difference between the lake and the air above it. Because water has a high specific heat, it warms and cools much more slowly than the air around it. All summer, the sun heats the lake, which stays warm deep into autumn. When air temperatures dip, we get the necessary temperature difference for lake-effect snow.

As the cool air passes over the lake, moisture from the water evaporates and the air directly above the surface heats up. This warm, wet air rises and condenses, quickly forming heavy clouds. The rate of change in temperature as you move up through the air is known as the "lapse rate"; the greater the lapse rate, the more unstable a system is—and the more prone it is to create weather events.

Encountering the shore only exacerbates the situation. Increased friction causes the wind to slow down and clouds to "pile up" while hills and variable topography push air up even more dramatically, causing more cooling and more condensation.

The other major factors that determine the particulars of a lake-effect snowstorm are the orientation of the wind and the specific lake. Winds blowing along the length of a lake create greater "fetch," the area of water over which the wind blows, and thus more extreme storms like the one currently pummeling the Buffalo area. The constraints of the lake itself create stark boundaries between heavy snow and just a few flurries and literal walls of snow that advance onto the shore. The southern and eastern shores of the Great Lakes are considered "snow belts" because, with winds prevailing from the northwest, these areas tend to get hit the hardest.

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