Hurricanes: Stronger, Slower, Wetter In The Future?

Scientists have developed a detailed analysis of how 22 recent hurricanes would be different if they formed under the conditions predicted for the late 21st century.

While each storm’s transformation would be unique, on balance, the hurricanes would become a little stronger, a little slower-moving, and a lot wetter.

In one example, Hurricane Ike — which killed more than 100 people and devastated parts of the U.S. Gulf Coast in 2008 — could have 13 percent stronger winds, move 17 percent slower, and be 34 percent wetter if it formed in a future, warmer climate.

Other storms could become slightly weaker (for example, Hurricane Ernesto) or move slightly faster (such as Hurricane Gustav). None would become drier. The rainfall rate of simulated future storms would increase by an average of 24 percent.

The study, led by scientists at the National Center for Atmospheric Research (NCAR) and published in the Journal of Climate, compares high-resolution computer simulations of more than 20 historical, named Atlantic storms with a second set of simulations that are identical but for a warmer, wetter climate that’s consistent with the average scientific projections for the end of the century.

A future with Hurricane Harvey-like rains

“Our research suggests that future hurricanes could drop significantly more rain,” said NCAR scientist Ethan Gutmann, who led the study. “Hurricane Harvey demonstrated last year just how dangerous that can be.”

Harvey produced more than 4 feet of rain in some locations, breaking records and causing devastating flooding across the Houston area.

The research was funded by the National Science Foundation (NSF), which is NCAR’s sponsor, and by DNV GL (Det Norske Veritas Germanischer Lloyd), a global quality assurance and risk management company.

“This study shows that the number of strong hurricanes, as a percent of total hurricanes each year, may increase,” said Ed Bensman, a program director in NSF’s Division of Atmospheric and Geospace Sciences, which supported the study. “With increasing development along coastlines, that has important implications for future storm damage.”

Tapping a vast dataset to see storms

With more people and businesses relocating to coastal regions, the potential influence of environmental change on hurricanes has significant implications for public safety and the economy.

Last year’s hurricane season, which caused an estimated $215 billion in losses according to reinsurance company Munich RE, was the costliest on record.

It’s been challenging for scientists to study how hurricanes might change in the future as the climate continues to warm. Most climate models, which are usually run on a global scale over decades or centuries, are not run at a high enough resolution to “see” individual hurricanes.

Most weather models, on the other hand, are run at a high enough resolution to accurately represent hurricanes, but because of the high cost of computational resources, they are not generally used to simulate long-term changes in climate.

For the current study, the researchers took advantage of a massive new dataset created at NCAR. The scientists ran the Weather Research and Forecasting (WRF) model at a high resolution (4 kilometers, or about 2.5 miles) over the contiguous United States over two 13-year periods.

The simulations took about a year to run on the Yellowstone supercomputer at the NCAR-Wyoming Supercomputing Center in Cheyenne.

The first set of model runs simulates weather as it unfolded between 2000 and 2013, and the second simulates the same weather patterns but in a climate that’s warmer by about 5 degrees Celsius (9 degrees Fahrenheit) — the amount of warming that may be expected by the end of the century.

Drawing on the vast amount of data, the scientists created an algorithm that enabled them to identify 22 named storms that appear with very similar tracks in the historic and future simulations, allowing the hurricanes to be more easily compared.

As a group, storms in simulations of the future had 6 percent stronger average hourly maximum wind speeds than those in the past. They also moved at 9 percent slower speeds and had 24 percent higher average hourly maximum rainfall rates. Average storm radius did not change.

Each storm unique

“Some past studies have also run the WRF at a high resolution to study the impact of climate change on hurricanes, but those studies have tended to look at a single storm, like Sandy or Katrina,” Gutmann said.

“What we find in looking at more than 20 storms is that some change one way, while others change in a different way. There is so much variability that you can’t study one storm and then extrapolate to all storms.”

But there was one consistent feature across storms: They all produced more rain.

While the study sheds light on how a particular storm might look in a warmer climate, it doesn’t provide insight into how environmental change might affect storm genesis. That’s because the hurricanes analyzed in this study formed outside the region simulated by the WRF model and passed into the WRF simulation as fully formed storms.

Other research has suggested that fewer storms may form in the future because of increasing atmospheric stability or greater high-level wind shear, though the storms that do form are apt to be stronger.

“It’s possible that in a future climate, large-scale atmospheric changes wouldn’t allow some of these storms to form,” Gutmann said. “But from this study, we get an idea of what we can expect from the storms that do form.”

Lightning In The Eyewall Of A Hurricane Beamed Antimatter Toward The Ground

Hurricane Patricia, which battered the west coast of Mexico in 2015, was the most intense tropical cyclone ever recorded in the Western Hemisphere. Amid the extreme violence of the storm, scientists observed something new: a downward beam of positrons, the antimatter counterpart of electrons, creating a burst of powerful gamma-rays and x-rays.

Detected by an instrument aboard NOAA’s Hurricane Hunter aircraft, which flew through the eyewall of the storm at its peak intensity, the positron beam was not a surprise to the UC Santa Cruz scientists who built the instrument. But it was the first time anyone has observed this phenomenon.

According to David Smith, a professor of physics at UC Santa Cruz, the positron beam was the downward component of an upward terrestrial gamma-ray flash that sent a short blast of radiation into space above the storm. Terrestrial gamma-ray flashes (TGFs) were first seen in 1994 by space-based gamma-ray detectors. They occur in conjunction with lightning and have now been observed thousands of times by orbiting satellites. A reverse positron beam was predicted by theoretical models of TGFs, but had never been detected.

“This is the first confirmation of that theoretical prediction, and it shows that TGFs are piercing the atmosphere from top to bottom with high-energy radiation,” Smith said. “This event could have been detected from space, like almost all the other reported TGFs, as an upward beam caused by an avalanche of electrons. We saw it from below because of a beam of antimatter (positrons) sent in the opposite direction.”

One unexpected implication of the study, published May 17 in the Journal of Geophysical Research: Atmospheres, is that many TGFs could be detected via the reverse positron beam using ground-based instruments at high altitudes. It’s not necessary to fly into the eye of a hurricane.

“We detected it at an altitude of 2.5 kilometers, and I estimated our detectors could have seen it down to 1.5 kilometers. That’s the altitude of Denver, so there are a lot of places where you could in theory see them if you had an instrument in the right place at the right time during a thunderstorm,” Smith said.

Despite the confirmation of the reverse positron beam, many questions remain unresolved about the mechanisms that drive TGFs. Strong electric fields in thunderstorms can accelerate electrons to near the speed of light, and these “relativistic” electrons emit gamma-rays when they scatter off of atoms in the atmosphere. The electrons can also knock other electrons off of atoms and accelerate them to high energies, creating an avalanche of relativistic electrons. A TGF, which is an extremely bright flash of gamma-rays, requires a large number of avalanches of relativistic electrons.

“It’s an extraordinary event, and we still don’t understand how it gets so bright,” Smith said.

The source of the positrons, however, is a well known phenomenon in physics called pair production, in which a gamma ray interacts with the nucleus of an atom to create an electron and a positron. Since they have opposite charges, they are accelerated in opposite directions by the electric field of the thunderstorm. The downward moving positrons produce x-rays and gamma-rays in their direction of travel when they collide with atomic nuclei, just like the upward moving electrons.

“What we saw in the aircraft are the gamma-rays produced by the downward positron beam,” Smith said.

First author Gregory Bowers, now at Los Alamos National Laboratory, and coauthor Nicole Kelley, now at Swift Navigation, were both graduate students at UC Santa Cruz when they worked together on the instrument that made the detection. The Airborne Detector for Energetic Lightning Emissions (ADELE) mark II was designed to observe TGFs up close by measuring x-rays and gamma-rays from aircraft flown into or above thunderstorms.

Getting too close to a TGF could be hazardous, although the risk drops off rapidly with distance from the source. The gamma-ray dose at a distance of one kilometer would be negligible, Smith said. “It’s hypothetically a risk, but the odds are quite small,” he said. “I don’t ask pilots to fly into thunderstorms, but if they’re going anyway I’ll put an instrument on board.”

Smith’s group was the first to detect a TGF from an airplane using an earlier instrument, the ADELE mark I. In that case, the upward beam from the TGF was detected above a thunderstorm. For this study, the ADELE mark II flew aboard NOAA’s Hurricane Hunter WP-3D Orion during the Atlantic hurricane season.

India Dust Storms: More Than 125 Killed As Storms Continue

At least 125 people are now reported to have died in fierce dust storms in northern India, with officials warning of more bad weather to come.

High-speed winds and lightning devastated many villages, bringing down walls and leaving dozens injured.

An Uttar Pradesh relief commissioner’s office spokesperson told AFP news agency the death toll was the highest from such storms in at least 20 years.

Officials have said the death toll could rise as more bodies are found.

Wind speeds were around 132 km/h (82mph) accompanied by hail storms and heavy lightning, officials said.

Fear amid the ruins

Villagers in Badhera, in the worst affected district of Agra in Uttar Pradesh, say they had had absolutely no warning of the storm that devastated their homes.

This is despite senior police officials saying that an alert was issued across the northern state.

The storm killed three people in the village, while several others were taken to hospital with serious injuries.

Ten-year-old Abhishek Kumar was asleep with his family when the storm struck. Their house collapsed, trapping him and his brother in the debris. Villagers dug them out but while Abhishek survived, his brother did not.

Dhambi Singh also suffered injuries but had to leave hospital to perform the last rites for his father who died when the roof of their house caved in.

Villagers are now worried as they have been warned that a similar storm could strike the region again in the next 72 hours.

“People should be alert,” the relief commissioner’s office told AFP.

In the two states of Uttar Pradesh and Rajasthan, the storm brought down electricity, uprooted trees, destroyed houses and killed livestock.

Tornadoes, Strong Winds Injure Four In Southern Alabama

Four people were injured Sunday when a Southern storm system sent a tornado ripping through an RV park in coastal Alabama, authorities said.

The National Weather Service said two tornadoes were tracked through Baldwin County on Sunday. One of them, in Foley, about 20 miles southeast of Mobile, caused widespread damage, Fire Chief Joseph Darby told NBC affiliate WPMI of Mobile.

Darby said that five RVs were overturned and that four people were injured at Anchors Aweigh RV Resort. The extent of their injuries couldn’t immediately be determined.

“I could see the rain suddenly turning horizontal and the wind really picked up and our camper started to shake and then I told my husband — I grabbed my dog and told my husband — let’s get down because something is going on,” Peggy Stanton of Michigan, who was visiting Foley with her husband, told WPMI.

The tornado was part of a severe weather system that threatens to douse the Southeast with heavy rain through the early part of the week, the National Weather Service said. Rainfall totals of 3 to 6 inches are expected in the southern Appalachians, where flood watches have been issued through Tuesday morning.

Locally heavy rainfall could cause flash flooding to a larger section the Southeast and the mid-Atlantic through Tuesday night, it said.

Severe winds, including at least one possible tornado, were also reported in northern Florida late Saturday and Sunday. The Okaloosa County Sheriff’s said numerous trees were down, especially in Fort Walton Beach, where city officials said City Hall was damaged by a fallen tree.

Two Tornadoes Reported, 1 Person Killed As Strong Storms Cross NC; Flooding Still Possible

A line of severe weather spread across North Carolina on Sunday, bringing heavy rainstorms and two reported tornadoes that toppled trees and ripped apart homes in Greensboro and Reidsville. At least one person was found dead, according to news outlets in the Piedmont.

The Triangle saw heavy rain, gusts of winds and scattered power outages that affected thousands in Raleigh, Durham and Orange County, but no reports of tornadoes.

Emergency workers warned of potential flash floods and the ponding of water on roads.

Tornado watches had been extended throughout Sunday as fast-moving storms moved eastward across the state.

In Greensboro, the News & Record and WFMY TV described several areas that had damage from high winds, with much of it east of U.S. 29. At least seven homes were damaged, as well as a mobile classroom at an elementary school in Greensboro.

Trees were down, pulling power lines with them, making streets impassable in some places. One death was reported in Greensboro.

The National Weather Service in Raleigh reported that a tornado was spotted near U.S. 29 and East Gate City Boulevard in Greensboro in Guilford County at 5:15 p.m.

All public schools in Guilford are closed on Monday.

Hawaii Storm Strands Dozens At Red Cross Evacuation Shelter

LIHUE, Hawaii – Dozens of people are stranded at a Red Cross shelter on Kauai after a storm dropped over 2 feet of rain, causing massive flooding and grounding rescue helicopters.

Hawaii Gov. David Ige issued an emergency proclamation for the island where heavy rainfall damaged or flooded dozens of homes in Hanalei, Wainiha, Haena and Anahola.

About 40 people – mostly tourists – were stranded Sunday at Hanalei Elementary School, where the American Red Cross had opened an evacuation shelter. They briefly ran out of food and water.

Coralie Chun Matayoshi, chief executive officer of the Red Cross in Hawaii, said the county’s Department of Parks and Recreation offered to deliver food to the evacuees by personal watercraft, but a nearby business was also dealing with flooding and unable to provide the supplies to be delivered. The Hawaii Guard offered to deliver food by air, but the weather kept the helicopters grounded.

Officials will continue rescue efforts when the weather improves.

The Kauai Fire Department was coordinating with the Coast Guard and the Honolulu Fire Department to provide air and search and rescue operations on the North Shore.

The National Weather Service recorded almost 27 inches (68 centimeters) of rainfall in a 24-hour period in Hanalei.

Kauai County spokeswoman Sarah Blane said county officials had to call in off-duty firefighters, police officers and lifeguards Saturday night to rescue about a half-dozen people who were trapped by rising floodwaters in Hanalei.

The American Red Cross opened evacuation shelters at Kapaa Middle School, the Church of the Pacific in Princeville and at the elementary school.

There were no immediate reports of injuries.

Weather Phenomena Such As El Niño Affect Up To Two-Thirds Of The World’s Harvests

According to researchers at Aalto University, Finland, large-scale weather cycles, such as the one related to the El Niño phenomenon, affect two-thirds of the world’s cropland. In these so called climate oscillations, air pressure, sea level temperature or other similar factors fluctuate regularly in areas far apart in a way that causes rain and temperature patterns to shift significantly.

‘During recent years, researchers’ ability to predict these oscillations has improved significantly. With this research, we highlight the potential of utilizing this improved forecasting skill in agricultural planning. This could improve the resilience of agriculture to climate related shocks, which can improve food security in many areas across the globe’, says Matias Heino, a doctoral candidate at Aalto University.

The study, published in Nature Communications, is the first global study which examines the impacts of the El Niño-Southern Oscillation as well as the similar North Atlantic Oscillation, and the Indian Ocean Dipole, on global food crop production.

These climate oscillations can be divided into different episodes depending on their phase. It is already known that El Niño and its opposite phase, La Niña, have a clear effect on corn, soy, rice, and wheat yields in many areas across South Asia, Latin America and southern Africa.

‘Our study showed that the North Atlantic Oscillation, NAO, significantly affects crop production in many parts of Europe, but also in North Africa and the Middle East’, says assistant professor Matti Kummu from Aalto University.

The North Atlantic Oscillation describes the relationship between the Icelandic low pressure and the Azores high pressure areas. When the air pressure in Iceland is significantly lower than in the Azores, stronger winds increase the transport of warm, moist air from the Atlantic to Europe. During the other phase of the North Atlantic Oscillation, when the air pressure difference is smaller, less than average amounts of mild air flow to Europe. It makes the winters colder and less rainy.

When the Atlantic air pressure difference has been high, the productivity of crops in Europe have reduced by 2 per cent compared to the average. The effect has been particularly strong in places like Spain and the Balkans, where the decrease in productivity has been as much as 10 per cent. Crop productivity reductions, by up to 6 per cent, were also observed in North Africa and the Middle East. During the other phase of NAO, when the air pressure difference is weaker, the same areas have shown positive changes, in crop productivity.

In the Indian Ocean Dipole, the surface water temperature of the Indian ocean fluctuates regularly in the ocean’s eastern and western parts: When the surface water is warmer in the Western Indian Ocean, the temperatures in the Eastern Indian Ocean tend to be lower, and vice versa. The IOD phenomenon affects food crop production particularly in Australia, where the crop productivity may, depending IOD’s phase, be up to 8 per cent smaller or 6 per cent larger compared to the average.

This study has been conducted in collaboration with researchers from Columbia University, Vrije Universiteit Amsterdam, Potsdam Institute for Climate Impact Research (PIK), and University of Bonn.