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.

7 Wintery Facts About Ice, Freezing Rain, and Sleet

Razvan Socol via Flickr | CC BY-SA 2.0
Razvan Socol via Flickr | CC BY-SA 2.0

Whether you’re trying to fly across the country or you just want to buy groceries, a winter storm can have a significant impact on your life. But how can you tell if the ice, sleet, or freezing rain will prompt a winter weather advisory or a snow day from work? Here are a few facts about winter storm weather to help you prepare.

1. Freezing rain and sleet are a winter storm's silent hazards.

Ice in the form of freezing rain and sleet is just as big of a threat as snow, and often result in a winter weather advisory being issued for the affected region. Ice is arguably more dangerous than the fluffy white stuff. Snow is generally manageable: You can shovel it and plow it, and while others are doing the work, you can enjoy a snow day with a cup of hot cocoa. You can’t do that with ice.

For the most part, frozen water becomes solidly affixed to any exposed and untreated surface. There comes a point when ice is entirely unmanageable. Even a giant vehicle with four-wheel drive is useless when it can’t grip the surface it’s sliding on. Ice—mostly from freezing rain—is not only dangerous because of the associated travel hazards, but also because of the damage it can cause.

2. A winter storm with Freezing rain is dangerous.

Freezing rain is rain that freezes when it comes in contact with an exposed surface like a tree or a sidewalk. A small amount of freezing rain can leave a thin glaze of ice on just about any surface, creating a situation where surfaces that look wet are really icy instead. A steadier freezing rain will allow a crust of solid ice to form on trees and power lines, weighing them down to the point of breaking. Extreme ice accretions—over an inch—can cause significant damage and disrupt life for weeks at a time.

3. Freezing rain is actually melted snowflakes.

Freezing rain forms when there’s an inversion layer present during a winter storm. An inversion layer occurs when a layer of warm air gets sandwiched between two colder air masses. Snowflakes fall through the warm layer and completely melt before reentering the subfreezing air near the surface. This newly formed raindrop can’t freeze back into ice because it doesn’t have a nucleus around which to freeze, so the raindrop becomes supercooled, meaning it remains in liquid state even as its temperature drops below freezing. Once the supercooled raindrop reaches the ground, the water instantly freezes into ice.

4. All that ice from freezing rain is extremely heavy.

If you’ve ever had to carry a case of bottled water up a flight of stairs, you know that even a little bit of water is extremely heavy. Imagine even more weight on a much more fragile surface, and that’s what you get during an ice storm. Damage to trees can begin with just a quarter-inch of ice, with more damage to bigger and sturdier trees as the crust of ice grows thicker. The Weather Channel points out that just a half-inch of ice accretion on a standard power line can add 500 pounds of extra weight to the line and the poles supporting it. Extreme ice storms can cause as much damage as an intense tornado, as even a couple of inches of ice adds enough weight to crumple the tall steel transmission towers that carry high-voltage power lines—and those take a while to repair.

5. Sleet is freezing rain's annoying cousin. 

A close relative to freezing rain is sleet. Sleet, also known as ice pellets, forms through the same process as freezing rain. Snowflakes destined to become sleet also fall through a warm layer of air, but one that isn’t deep enough to melt the snowflake completely. Once the partially melted snowflake enters subfreezing air, there are still a couple of ice crystals left in the raindrop that allow the raindrop to freeze into a little ball of ice before reaching the ground. The result is an ice pellet about the size of half a grain of rice that makes a distinctive tinking noise as it bounces off cars, vegetation, and roofs.

6. Sleet is like snow that freezes solid. 

Sleet looks like snow and it accumulates like snow. It’s easy to mistake sleet for snow if you’re not a hardcore weather geek, but with enough accumulation, even the casual observer will know something is different pretty quickly. Sleet has a nasty habit of freezing into solid ice within a few hours of falling, especially if the Sun comes out or if temperatures briefly rise above freezing once the precipitation stops. Once this hardening occurs, it can be next to impossible to remove it from sidewalks, driveways, and roads until there’s a major thaw. In the southeastern United States, sleet is particularly common (and problematic), since the region is prone to warm air intruding on its winter storms and many municipalities don’t have enough snow equipment to clear the roads before that sleet freezes solid.

7. When a winter storm warning is issued, join the grocery lines.

Everyone makes fun of the throngs of panicked shoppers before a snowstorm, but stocking up on groceries before a winter storm is a pretty good idea for even the biggest cynic. If freezing rain knocks out power for an extended period of time, stores and restaurants will be forced to close until power is restored and they get fresh shipments of food. If that happens, you’re pretty much on your own for food and drink until conditions improve. Before a storm arrives, make sure you get plenty of food and beverages that you don’t have to cook or keep fresh.

Lake Michigan Has Frozen Over, and It's an Incredible Sight

Scott Olson, Getty Images
Scott Olson, Getty Images

A polar vortex has brought deadly temperatures to the Midwest this week, and the weather is having a dramatic effect on one of the region's most famous features. As the Detroit Free Press reports, parts of Lake Michigan have frozen over, and the ice coverage continues to grow.

The Lake Michigan ice extent has increased rapidly throughout January, starting around 1 percent on the first of the month and expanding to close to 40 percent by the end of the month. Yesterday was the coldest January 30 in Chicago history, with temperatures at O'Hare Airport dropping to -23°F. Even though it's frozen, steam can be seen rising off Lake Michigan—something that happens when the air above the lake is significantly colder than the surface. You can watch a stream of this happening from a live cam below.

Lake Michigan's ice coverage is impressive, as these pictures show, but it's still far from breaking a record. Though Lake Michigan has never frozen over completely, it came close during the winter of 1993 to 1994 when ice reached 95 percent coverage.

Midwestern states like Wisconsin, Michigan, Illinois, and Indiana aren't the only places that have been hit hard by the cold this winter. At the United States/Canada border, Niagara Falls froze to a stop in some spots, a phenomenon that also produced some stunning photographs.


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[h/t Detroit Free Press]

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