Storms Head Across the U.S. This Week

Scott Olson/Getty Images
Scott Olson/Getty Images

We just lived through one of the warmest winters in recent memory. The warmth and relative lack of storminess was odd compared to a normal year, but the weather was downright quiet compared to what we've seen over the last couple of years. Unfortunately, our luck is running out as the Sun creeps into the Northern Hemisphere and the atmosphere slowly warms up. The clash of the seasons will cause a steady train of storms to glide across the country through the end of March, bringing along with them noticeably rapid changes in weather from day to day, including the risk for severe thunderstorms and some beneficial heavy rainfall.


The forecast position of the jet stream from the GFS weather model on the evening of Monday, March 27, 2017, showing three troughs (southward dips) in the jet stream as they cross the United States. Image Credit: Tropical Tidbits

 
Current weather models suggest that a series of upper-level troughs—elongated areas of lower air pressure—will come ashore on the West Coast every couple of days for the next two weeks, each wave taking about three days to traverse the length of the United States before retreating over the Atlantic Ocean. Each trough will be sandwiched between ridges of high pressure, which are associated with warmer air and calmer skies. This trough-ridge combination will allow warm, unstable air to flow north from the Gulf of Mexico before the trough arrives to take advantage of the favorable atmosphere ahead of it. The end result will be heavy rain and thunderstorms, some of which could turn severe.

The greatest risk for severe thunderstorms with each wave will lie across the southern Plains and interior sections of the Gulf Coast states, exactly where you'd expect dangerous weather to develop at the end of March. The extent of the severe weather depends on how much instability, moisture, and wind shear are present when the storms bubble up. If the right mix of ingredients doesn't come together at the right time, the weather won't be much more than an inconvenience. If storms are able to take advantage of the right conditions, though, all types of severe weather—damaging winds, large hail, and tornadoes—will be possible with each outbreak of severe thunderstorms.

It shouldn't come as too much of a surprise that severe weather is ramping up as we get closer to April. We're rapidly approaching prime season for severe thunderstorms and tornadoes. The average number of tornadoes that touch down each day climbs rapidly between the end of March and the beginning of summer, with each day of spring becoming historically more favorable for nasty severe weather outbreaks.

The Weather Prediction Center's precipitation forecast (in inches) between March 24 and March 31, 2017. Image Credit: NOAA/WPC

 
The silver lining to the cycles between calm and stormy is that it will bring much-needed rain to just about everyone east of the Rockies who are currently experiencing drought conditions. The same weather pattern that allowed California to climb out of its drought in just a couple of months also dried the eastern half of the country to the point of drought. Moderate to severe drought conditions covered nearly 16 percent of the contiguous United States on the U.S. Drought Monitor's analysis for March 21, with the worst drought covering the central Plains and much of the East Coast.

Rain from the upcoming train of storm systems will drop several inches of rain over a widespread area, helping to put a small dent in the drought. It won't be enough to cure the parched earth in many places, but as Californians will tell you, any amount of rain can help.

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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