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.

12 Powerful Facts About Hurricanes

iStock/shaunl
iStock/shaunl

Hurricanes are a stunning, and dangerous, display of nature’s power. They’re some of the largest and most intense storms nature can produce. Today, we know more about these systems and have an easier time measuring and predicting them than ever before. There’s more than meets the eye when it comes to hurricanes. As the 2019 hurricane season kicks off (it runs from June 1st through November 30th), here are some things you might not know about these dangerous storms.

1. Hurricanes are only "hurricanes" around North America.

A tropical cyclone is a compact, low-pressure system fueled by thunderstorms that draw energy from the heat generated by warm ocean waters. These tropical cyclones acquire different names depending on how strong they are and where in the world they form. A mature tropical cyclone is called a hurricane in the Atlantic and eastern Pacific Oceans. What’s known as a hurricane in the Atlantic is called a typhoon near Asia and simply a cyclone everywhere else in the world.

2. Hurricanes come in all shapes and sizes.

Not all hurricanes are picture-perfect. Some storms can look so disorganized that it takes an expert eye and advanced technology to spot them. A full-fledged hurricane can be as small as a few dozen miles across or as large as one-half of the United States, as was the case with Typhoon Tip in the western Pacific Ocean in 1979. The smallest tropical cyclone on record was 2008’s Tropical Storm Marco, a tiny storm in the Gulf of Mexico that almost made it to hurricane strength. Marco’s strong winds only extended 12 miles from the eye of the storm—a distance smaller than the length of Manhattan.

3. The greatest danger in a hurricane is in the eyewall.

The spiraling bands of wind and rain that radiate from the center of a hurricane are what give these storms their distinctive buzzsaw shape. These bands can cause damage, flooding, and even tornadoes, but the worst part of a hurricane is the eyewall, or the tight group of thunderstorms that rage around the center of the storm. The most severe winds in a hurricane usually occupy a small part of the eyewall just to the right of the storm’s forward motion, an area known as the right-front quadrant. The worst damage is usually found where this part of the storm comes ashore.

4. The eye of a hurricane is very warm.

The core of a hurricane is very warm—they are tropical, after all. The eye of a hurricane is formed by air rushing down from the upper levels of the atmosphere to fill the void left by the low air pressure at the surface. Air dries out and warms up as it rapidly descends through the eye toward the surface. This allows temperatures in the eye of a strong hurricane to exceed 80°F thousands of feet above the Earth's surface, where it’s typically much colder.

5. You can tell a lot about a hurricane by its eye.

Like humans, you can tell a lot about a hurricane by looking it in the eye. A ragged, asymmetrical eye means that the storm is struggling to strengthen. A smooth, round eye means that the storm is both stable and quite strong. A tiny eye—sometimes called a pinhole or pinpoint eye—is usually indicative of a very intense storm.

6. Some hurricanes have two eyes.

An eye doesn’t last forever. Storms frequently encounter a process known as an “eyewall replacement cycle,” which is where a storm develops a new eyewall to replace the old one. A storm weakens during one of these cycles, but it can quickly grow even more intense than it originally was once the replacement cycle is completed. When Hurricane Matthew scraped the Florida coast in October 2016, the storm’s impacts were slightly less severe because the storm underwent an eyewall replacement cycle just as it made its closest approach to land.

7. The strong winds that a hurricane creates are only part of the danger.

While strong winds get the most coverage on the news, wind isn’t always the most dangerous part of the storm. More than half of all deaths that result from a landfalling hurricane are due to the storm surge, or the sea water that gets pushed inland by a storm’s strong winds. Most storm surges are relatively small and only impact the immediate coast, but in a larger storm like Katrina or Sandy, the wind can push deep water so far inland that it completely submerges homes many miles from the coast.

8 California rarely sees tropical cyclones.

It can seem odd that California occupies hundreds of miles of coastline but always seems to evade the hurricane threat faced by the East Coast. California almost never sees tropical cyclones because the ocean is simply too cold to sustain a storm. Only a handful of tropical cyclones have ever reached California in recorded history—the worst hit San Diego in 1858. The San Diego Hurricane was an oddity that’s estimated to have reached category 1 intensity as it brushed the southern half of the Golden State.

9. Hurricane hunters fly planes into storms.

Aside from satellite and radar imagery, it’s pretty hard to know exactly what a hurricane is doing unless it passes directly over a buoy or a ship. This is where the Hurricane Hunters come in, a brave group of scientists with the United States Air Force and NOAA who fly specially outfitted airplanes directly into the worst of a storm to measure its winds and report back their findings. This practice began during World War II and has become a mainstay of hurricane forecasting in the decades since.

10. Hurricane hunters drop sensors to measure waves.

The Hurricane Hunters assess the storm with all sorts of tools that measure temperature, pressure, wind, and moisture, and have weather radar onboard to give them a detailed view of the entire storm. They regularly release dropsondes to "read" the inside of the storm. Dropsondes are like weather balloons in reverse: instead of launching weather sensors from the ground into the sky, they drop them down through the sky to the ground. The Hurricane Hunters also have innovative sensors that measure waves and sea foam and use the data to accurately estimate how strong the winds are at the surface.

11. We started naming storms to keep track of them.

Meteorologists in the United States officially started naming tropical storms and hurricanes in the 1950s to make it easier to keep track in forecasts and news reports. Since then, naming tropical cyclones has become a worldwide effort coordinated by the World Meteorological Organization, the United Nations agency responsible for maintaining meteorological standards. Today, the Atlantic Ocean and eastern Pacific Ocean each receive a list of alternating masculine and feminine names that are reused every six years.

12. Names are retired if the storm was especially destructive.

If a storm is particularly destructive or deadly, the WMO will “retire” the name from official lists so it’s never used again out of respect for the families of the storm’s victims and survivors. When a name is retired, another name starting with the same letter takes its place. More than 80 names have been retired from the Atlantic Ocean’s list of names since 1954. Earlier this year, it was announced that the names Florence and Michael were being retired as a result of the damage they caused during the 2018 hurricane season; they will be replaced with Francine and Milton when the list is reused in 2024.

This piece originally ran in 2017; it has been updated for 2019.

Denver is About to Experience Summer and Winter Temperatures Within 24 Hours

iStock.com/mphotoi
iStock.com/mphotoi

In a story tailor-made for exhaustive Weather Channel coverage, Denver, Colorado is about to experience one of the more bizarre weather shifts in recent memory. After an expected Tuesday high of 80°F, residents can anticipate a dramatic shift down to 32°F by midday Wednesday, with an initial half-inch of snow accumulation increasing to up to 7 inches by Wednesday night.

Put another way: Citizens who need to make sure they hydrate in the warm temperatures Tuesday will have to bring out the parkas the following day.

The Denver Post reports that the warm air coming ahead of the cold can result in a clash of air masses, prompting areas of low pressure that can create forceful and damaging weather conditions. The storm could bring winds of up to 60 miles per hour and possibly even cause power outages. Snow accumulation should dissipate by the weekend, when temperatures are expected to climb back into the 60s.

The high temperature record for April 9 in Denver is 81°F, set in 1977.

[h/t The Denver Post]

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