Hurricanes From Three Million Years Ago Give Us Clues About Present Storms

Studying hurricane and tropical storm development from three million years ago might give today’s forecasters a good blueprint for 21st century storms, says a team of international researchers that includes a Texas A&M University atmospheric sciences professor.

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Robert Korty, associate professor in the Department of Atmospheric Sciences at Texas A&M, along with colleagues from China, Norway, and the University of Wisconsin, have had their work published in the current issue of PNAS (Proceedings of the National Academy of Sciences).

The team studied storm development from the Pliocene era, roughly three million years ago, and chose that time period because it was the last time Earth had as much carbon dioxide as it does now, and the changes in climate from it can play a major role in storm formation and intensity.

Using computer models and simulations, the team found an increase in the average intensity during the period and the storms most often moved into higher latitudes — to a more northward direction.

“There seems to be a limit on how strong these ancient storms might be, but the number getting close to the limit appears to be larger during warmer periods,” Korty explains.

“They reached their peak intensity at higher latitudes, following an expansion of tropical conditions with warming. It is consistent with smaller changes in the same patterns that we have observed over recent decades and project to continue over the next 100 years. I think it gives us greater confidence in some trends we are witnessing about how storms may change in future years.”

Researchers today know that the oceans continued to be relatively warm during the Pliocene era, though there has been some uncertainty where waters were warmest. Their study found that the increase in average intensity and in the poleward expansion occurred regardless of where the greatest change in temperatures occurred in the Pliocene.

Korty says the study adds more evidence “that future storms are likely to be stronger in their intensity and to remain strong even as they move out of the tropics.”

Ice Shelf Vibrations Cause Unusual Waves In Antarctic Atmosphere

Low-frequency vibrations of the Ross Ice Shelf are likely causing ripples and undulations in the air above Antarctica, a new study finds. Using mathematical models of the ice shelf, the study’s authors show how vibrations in the ice match those seen in the atmosphere, and are likely causing these mysterious atmospheric waves.

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Scientists at McMurdo Station detected unusual atmospheric waves with an altitude between 30 to 115 kilometers (20 to 70 miles) above Antarctica in 2011. The waves, which have a long period and take hours to cycle, were observed for several years. Scientists routinely observe atmospheric waves around the world, but the persistence of these waves made them unusual, and scientists didn’t know what was causing them.

The new research solves this mystery by connecting the atmospheric waves to vibrations of the Ross Ice Shelf — the largest ice shelf in the world with an area of almost half a million square kilometers (188,000 miles), roughly the size of France. Imperceptible vibrations of the ice shelf, caused by ocean waves and other forces, are transferred and amplified in the atmosphere, according to the new study.

If the study’s predictions are correct, scientists could use these atmospheric waves to measure properties of the ice shelf that are normally difficult to track, such as the amount of stress the ice shelf is under from ocean waves.

“If atmospheric waves are generated by ice vibrations, by rhythmic vibrations of ice — then that carries a lot of information of the ice shelf itself,” said Oleg Godin, a professor at the Naval Postgraduate School in Monterey, California, and lead author of the new study, published in the Journal of Geophysical Research: Space Physics, a journal of the American Geophysical Union.

This information could help scientists better understand the status and stability of ice shelves, which are permanently floating sheets of ice connected to landmasses. Scientists closely monitor the size and movement of ice shelves because when they break up, they indirectly contribute to sea level rise through their impact on land ice.

“Ice shelves buffer or restrain land ice from reaching the ocean,” said Peter Bromirski, a research oceanographer at Scripps Institute of Oceanography in La Jolla, California, who was not involved in the new study. “The long term evolution of an ice shelf — whether or not it breaks up and disintegrates — is an important factor in how fast sea level will rise.”

Explaining the vibrations

In the new study, Godin and his co-author, Nikolay Zabotin, used two theoretical models of the Ross Ice Shelf to show vibrations within the ice could create the atmospheric waves.

One model approximates the ice shelf as a smooth rectangular slab of ice, while the other approximates the ice as a layered fluid. The authors incorporated known properties of the ice sheet such as elasticity, density, and thickness into each model to calculate the time it would take vibrations in the ice to complete one cycle.

They found both models predict that the ice shelf produces vibrations within a 3- to 10-hour period, which matches the duration of vibrations seen in the atmosphere. These ice shelf vibrations would likely also produce atmospheric waves with a vertical wavelength of 20 to 30 kilometers (12 to 18 miles), another feature of the observed waves.

“Even in this simplified description [of the ice], it readily explains the most prominent features of the observations,” Godin said. “That’s why it goes beyond hypothesis. I would say it’s now a theory.”

The vibrations are transferred from the ice shelf to the atmosphere through direct contact with the air above the ice shelf, according to the new study. While the vibrations of the ice sheet are small, the atmospheric disturbances they create can be large because of reduced air pressure high in the atmosphere. For example, an ice shelf vibration one centimeter in amplitude pushes on the air directly above it. As the vibration cascades upward, it can grow in amplitude to move air hundreds of meters up and down when the wave reaches the less-dense air high in the atmosphere, Godin said.

The size of these atmospheric waves makes them easy to observe with radar and Lidar, a radar-like system using laser light to scan the atmosphere. Godin and Zabotin plan to use an advanced research radar to study the atmospheric waves in more detail to better understand the behavior of the Ross Ice Shelf.

“There are suggestions in the literature that accelerated breakup of ice shelves will lead to rise of sea level by several meters by the end of the century,” Godin said. “Anything we can do to quantify what is going on with these large ice shelves is of huge importance.

Stalled Front And Tropical Storm Deluge Roads, Close Schools

NORFOLK, Va. – Flooding in coastal Virginia and North Carolina blocked roads and forced school closings Wednesday that affected for more than 100,000 students.

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A stalled weather system and the remnants of Tropical Storm Julia have brought days of rain and localized flooding to the region. The rain is expected to continue into Thursday.

National Weather Service Meteorologist Tim Gingrich said anywhere from 5 inches to 12 inches of rain have fallen “and it’s still raining.” He added that the rainfall has broken records for individual dates on Monday and Tuesday.

“We still have a flash flood watch for at least Norfolk, Chesapeake and Virginia Beach,” Gingrich added.

Gingrich said the worst should be over by Wednesday evening. But he said rain will still fall for much of Thursday before Julia’s remnants are expected to drift out to sea by the following day.

“Right now it’s sitting over a corner of northeast North Carolina and spinning,” he said of the storm.

Major school districts in Virginia’s south Hampton Roads region have canceled classes. So have two North Carolina counties, Currituck and Gates. Local media are reporting impassable roadways and highway ramps throughout the region.

Officials in Chowan County, North Carolina, reported on a website that at least two roads were washed out along with water lines serving 150 customers. Several others roads are impassable. Between five to 10 inches of rain has fallen there. The county remained under a flood warning until the late afternoon.

In Virginia Beach, resident Todd Solomon said he’s never seen rainstorms close schools without a hurricane bearing down.

Solomon lives in a flood-prone neighborhood. He said water flooded his backyard up to his house’s foundation but failed to enter the home. He said his neighborhood has fared pretty well, considering.

“A lot of parents were pretty surprised,” said Solomon who has a child in middle school. “The kids are pretty happy. They were texting, saying hey what are we going to do today? It was like summer or the weekend.”

Second Typhoon In Three Days Expected To Smash Taiwan

Taiwan is about to be soaked by its second severe storm in just three days, with typhoon Malakas forecast to pass by the northern end of the island early on Saturday.

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The tropical storm will tear past Taiwanese capital Taipei at around midday and is forecast to reach as high as a category four hurricane, with wind speeds exceeding 125 miles per hour (200 kilometers per hour).

It comes just two days after typhoon Meranti made landfall on the southern coast, leaving hundreds of thousands of homes without power.

On Friday afternoon, typhoon Malakas was hovering off the eastern coast of Taiwan and is forecast to curve up the country’s coastline, growing stronger and passing Taipei, before heading towards Japan.

“Even though the storm is not forecast to make a direct landfall on Taiwan at the moment, areas towards the north of Taitung county are forecast to receive tropical storm force winds beginning Saturday afternoon and lasting into Sunday morning,” CNN meteorologist Michael Guy said.

“Once the storm begins its track towards the northeast it will impact the Ryuku Islands with high surf, winds and rain.”

Taiwan’s Central Weather Bureau issued a typhoon warning for parts of the country on Friday, ahead of the storm’s arrival.

Tropical Storm Karl Forms in Eastern Atlantic

Tropical Storm Karl has formed in the far eastern Atlantic but currently poses no threat to land.

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Late Thursday night, Karl was located about 575 miles (930 km) west-northwest of the Cabo Verde Islands and about 1,930 miles (3,105 km) east of the Leeward Islands.

The National Hurricane Center in Miami says Karl is moving west at 14 mph (kph) with maximum sustained winds of 45 mph (75 kph). It was expected to continue toward the west or west-southwest for the next couple of days.

No coastal watches or warnings are in effect related to the storm.

Storm Julia Weakens Into A Depression, Meandering Off Of U.S. Coast

Tropical Storm Julia weakened into a depression and is expected to meander off the coast of Georgia and South Carolina for the next few days, the U.S. National Hurricane Center said on Thursday.

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Julia is located about 60 miles (95 km) south-southeast of Charleston, South Carolina with maximum sustained winds of 35 mph (55 kph), the Miami-based weather forecaster said.

“A slow and erratic motion is expected over the next couple of days, and the track forecast keeps Julia meandering offshore of the Georgia and southern South Carolina coastlines into Saturday,” the NHC said.

Julia, the 10th named storm of the 2016 Atlantic hurricane season, was moving northeast at 2 mph just off the U.S. coast, as little change TO its strength was expected during next two days, it said.

Heavy rain combined with high tides raised concerns of flooding in downtown Charleston, South Carolina, and other coastal parts of the state into Thursday morning, forecasters said.

Some residents in coastal communities were offered sandbags to prepare for flooding in low-lying areas.

Since late Tuesday, Julia has dumped heavy rains and toppled trees in the region, but has not caused significant damage, the National Weather Service said.

On Thursday morning, the hurricane center also was tracking a tropical depression that was expected to bring heavy rains to the Cape Verde islands off West Africa. On its forecasted track, the system would remain far away from the coastal United States through early next week.

Meranti: Strongest Super Typhoon Of The Year Barrels Toward China, Taiwan

Hundreds of people have been evacuated in southern Taiwan and China has issued a red alert as the region braces for the impact of the strongest storm of the year.

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Super Typhoon Meranti is barreling down on Taiwan, bringing wind speeds of up to 230 miles per hour (370 kph), faster than a Formula One race car, and torrential rains.

Schools and offices across the south of the island have closed and dozens of flights have been canceled, according to the official China News Agency.

Two people have been injured, and more than 260,000 households have lost power in counties across southern Taiwan, according to Taiwan authorities.

More than 370 domestic and international flights have been canceled and train services have also been suspended.

As of 7 a.m. local time Wednesday morning, around 1,500 people had been evacuated from the affected areas, Li Wei-sen, of the Taiwan Central Emergency Operating Center, told CNN.

Almost 4,000 military and police personnel have been deployed to the region to prepare for potential future evacuations, but he said authorities are not expecting major damage or destruction.

China braces for impact

While the 23 million people in Taiwan are likely to be buffeted and soaked by Meranti, the main brunt of the storm will fall on mainland China. The storm is expected to make landfall in Guangdong or Fujian provinces during the day on Thursday.

Authorities in six south-eastern provinces as well as Shanghai have initiated emergency response measures as the storm approaches, according to state run news agency Xinhua.

If the storm makes landfall in eastern Guangdong, it could be the strongest to hit the province in 47 years, Xinhua reported.

“It only took nine hours for Meranti to grow into a super typhoon from a typhoon,” Guangdong meteorologist Zhang Dong told the news agency.

“Packing winds between 202 to 220 kilometers per hour, it is interacting with another storm, Malakas, 1,000 kilometers away, and the route could be hard to predict.”

China’s National Meteorological Center issued a red typhoon warning at 6 a.m. local time Wednesday, while authorities warned that waves eight to 13 meters (26 to 42 feet) high could be expected in the northeastern part of the South China Sea.

Super typhoon

After a period of rapid intensification Monday and Tuesday, which saw Meranti grow from a Category 1 equivalent storm to that of a top-scale Category 5 in only 24 hours, the super typhoon has maintained winds of 190 mph (305 kph) for nearly 24 hours.

With current gusts of up to 230 mph (370 kph), Meranti is the strongest typhoon since Super Typhoon Haiyan devastated the Philippines in 2013 and is the strongest storm to come this close to Taiwan since 1959.

The storm is nearing the southern tip of Taiwan, and though its eye may pass a few miles south of the island, dangerous typhoon-force winds greater than 74 mph (120 kph) extend nearly 80 miles (125 km), and will cover much of Southern Taiwan.

From there the storm will track through toward the northwest and move into mainland China.

Storm veterans

Taiwan, despite being a frequent target for powerful Pacific typhoons, has a very good track record of limiting the storms’ deadly impacts. But as storms move into the mainland, they often turn deadlier. The flatter terrain — prone to storm surges and inland flooding — and higher population density often result in higher numbers of people killed or misplaced by the storm.

This was the case with a similar storm, Super Typhoon Nepartak, which hit in almost the same location as where Meranti is forecast to travel. Nepartak, which made landfall on July 8, caused at least three deaths in Taiwan and cut power to over half a million, but became much deadlier as it moved into mainland China.

Despite weakening to a tropical storm as it hit mainland China, Nepartak and its associated heavy rainfall of up to 10 inches (254 mm) killed more than 80 people. Meranti is expected to be much stronger than Nepartak when it hits mainland China, with winds around 130 mph (210 kph), which would make it equivalent to a major Category 4 hurricane in the Atlantic or Gulf of Mexico.