Tropical Storm Cindy Could Cause Major Flooding Across the Southeast This Week

A water vapor image of Tropical Storm Cindy on June 20, 2017. Darker green indicates higher moisture in the atmosphere.
A water vapor image of Tropical Storm Cindy on June 20, 2017. Darker green indicates higher moisture in the atmosphere.

The stewing heat and humidity of a young summer finally gave way to the first tropical cyclone to threaten the United States this year. Tropical Storm Cindy is gathering steam in the Gulf of Mexico this week, and it promises to bring heavy rains to just about everyone in the southeastern United States. It won’t be a strong storm when it makes landfall, but wind isn’t as much of a concern as the copious amounts of tropical moisture being dragged northward, culminating in lots of precipitation and the potential for flooding.

As of Wednesday, June 21, 2017, tropical storm warnings are in effect for parts of the Gulf Coast from areas west of Houston, Texas, to as far east as Pensacola, Florida. Tropical Storm Cindy had winds up to 60 mph at 8:00 a.m. EDT Wednesday morning, and forecasters expect the storm to maintain winds of around 50 mph as it nears landfall. Winds of 45 mph are what you'd see in a healthy thunderstorm, but constant blustery winds over wet soil will make it easier for trees and power lines to topple over.

The traditional hurricane forecasting map—showing the forecast track of the center of the storm with a cone of uncertainty sweeping along its expected path—doesn't do much good in this situation. Sure, some areas will see gusty winds and power outages, but the real story with Tropical Storm Cindy is its rain. Cindy is a lopsided tropical storm with almost all of its heavy rain and wind shoved off to the east of the low-pressure center by wind shear higher up in the atmosphere. That's common to see in a weak, early season storm like this. Cindy's heavy rain will extend far beyond the center of the storm due to its lopsidedness and large size, so the forecast tracks we're all used to seeing don't go far enough to cover the threat posed by this storm. (If you'd like to see for yourself, forecasts are always available on the National Hurricane Center's website.)

Rain forecasts for Tropical Storm Cindy
The Weather Prediction Center’s rainfall forecast from June 20, 2017, through June 27, 2017
Dennis Mersereau

Tropical Storm Cindy will produce rainfall totals in the double digits in some locations through the end of the week, and the moisture from its remnants will continue to track inland through the weekend. The Tuesday morning precipitation forecast from NOAA’s Weather Prediction Center called for a widespread area across the Southeast to see more than three inches of rain by the time the storm finally clears out of the picture at the end of the week. Moisture from a landfalling tropical system is usually bad enough, but this storm will run into a pesky stationary front draped across inland areas of the Southeast. This front will help wring out the moisture and make it rain harder and longer than it would have otherwise.

This much rain over a short period of time will lead to widespread flooding concerns. If you live in or are visiting affected areas, make sure you know more than one route to get to where you're going. More than half of all deaths in a tropical storm or hurricane are caused by drowning. It's impossible to tell how deep the water is on a road before you drive across it, and it takes a surprisingly small amount of moving water to lift a car and sweep it downstream.

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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