Cyclone Debbie Made Landfall in Australia

Cyclone Debbie approaching landfall in northeastern Australia on March 28, 2017. Image Credit: SSEC/Google Earth

 
A powerful cyclone came ashore on Australia’s northeastern coast on Tuesday, the most intense storm to strike the country in several years. Cyclone Debbie made landfall on the Queensland coast south of the town of Bowen, which lies about 300 miles southeast of Cairns. The storm hit land with winds in excess of 120 mph, which would make it the equivalent of a major hurricane on the Saffir-Simpson Hurricane Wind Scale used in the United States. Debbie stands out as an intense storm in an unusually quiet cyclone season in this part of the world. A storm of this magnitude hasn’t struck the country since Cyclone Yasi made landfall south of Cairns in February 2011.

Cyclone Debbie made landfall in an area that’s home to nearly 100,000 people, including the towns of Mackay and Bowen. Media reports indicate that local emergency response crews were worried that the town of Bowen, which found itself in the cyclone’s eyewall, would sustain substantial damage from the storm, as many of the town’s homes and businesses were built before more stringent construction standards were introduced in the 1980s [PDF]. The town of Mackay and its suburbs saw less intense winds from the cyclone, but residents along the coast were ordered to evacuate in anticipation of a dangerous storm surge.

Early reports of damage are few and far between, due to power and communications outages with the hardest-hit areas. Videos published online by storm chasers in the area show damage to trees and buildings as the storm came ashore.


An infrared satellite image of Cyclone Debbie on March 28, 2017. Warmer colors indicate higher cloud tops, associated with intense convection in the cyclone. Image Credit: SSEC

 
Cyclone Debbie formed under ideal conditions that allowed the storm to thrive. Sea surface temperatures off the northeastern Australian coast were around 80°F, there was ample tropical moisture to feed the storm, and the cyclone encountered almost no wind shear in the upper levels of the atmosphere to disrupt its development. The storm took advantage of the favorable conditions and underwent rapid intensification as it neared the Australian coast early on Tuesday morning local time. WeatherBELL’s Ryan Maue reported that satellite estimates pegged the cyclone’s peak winds at more than 140 mph at the storm’s strongest point. The storm weakened somewhat as it approached the coast due to an eyewall replacement cycle, a common process in strong tropical cyclones in which a new eyewall develops and chokes off the old eyewall, temporarily weakening the storm until the process is completed.

Tropical cyclones in the southwestern Pacific Ocean are most common between the months of November and April, though cyclones are possible at any point in the year. The peak of the season coincides with the heat of the summer toward the beginning of the year. Australia’s northern coast is vulnerable to major tropical cyclones. The last significant cyclone to strike this region of Queensland was Cyclone Marcia in 2015; the storm caused significant damage but thankfully resulted in no fatalities. Debbie threatens to be the strongest storm to make landfall since Yasi back in February 2011. Cyclone Yasi reached shore with winds of 155 mph, causing billions of dollars in damage.

The term “tropical cyclone” applies to any low-pressure system that develops over the ocean and feeds its energy off of thunderstorms near the center of the system rather than winds high in the atmosphere. Strong tropical cyclones are called “hurricanes” in the Atlantic and eastern Pacific Ocean, “typhoons” in the northwestern Pacific Ocean, and simply “cyclones” everywhere else in the world, including around Australia. All of the storms are structurally the same—the only difference is that they’re classified a little differently based on wind speeds.

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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