Space & Innovation

Quiet Hurricane Season Ahead, 10 years After Katrina

El Nino will likely keep hurricane activity tamped down this season, which marks 10 years since Katrina. Continue reading →

As the 10th anniversary of the busiest hurricane season on record approaches, forecasters and government officials are preparing for the start of the 2015 season. But unlike the 2005 season, which saw an unprecedented 28 storms - including one of the worst, Hurricane Katrina - this season is expected to see fewer than the average number of hurricanes.

The El Niño flourishing in the tropical Pacific will be the main force keeping a lid on storm development in the Atlantic Ocean basin, National Oceanic and Atmospheric Administration (NOAA) forecasters said Wednesday with the release of their seasonal hurricane outlook.

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Officials were quick to point out, however, that even an overall quiet season can see devastating storms. That was clearly illustrated in 1992 by the destruction wrought by Hurricane Andrew during a season that had only seven named storms. Because of that possibility, they emphasized preparation from the individual to the federal level.

"We're on the doorstep of the Atlantic season and we've got to be ready for whatever comes," NOAA administrator Kathryn Sullivan said during a press conference held in New Orleans, a nod to the upcoming Katrina anniversary.

Hurricane season officially begins on June 1 and lasts until Nov. 30, with the biggest flurry of storm activity generally coming from late August to early October. This season, NOAA forecasters expect to see anywhere from six to 11 tropical storms, of which only three to six are expected to become hurricanes.

It is possible that none of those hurricanes will reach major status - defined as Category 3 or higher on the Saffir-Simpson scale of hurricane strength - though the predicted range is up to two major hurricanes for the season.

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Counted in those numbers is Tropical Storm Ana, which formed before the official season in early May, making landfall on the South Carolina coast on May 10. Such early storms aren't entirely rare, happening every few seasons or so, though recent research suggests that global warming could stretch out the hurricane season by making conditions more conducive to storm formation over a longer period of time.

Most research into the effect of warming on tropical cyclones (the umbrella term for tropical storms, hurricanes and typhoons) has focused on how it might change the frequency or intensity of storms. That work is coalescing around the idea that warming will mean fewer storms overall, but that the ones that do form will skew stronger.

The most robust connection between hurricane and climate change is from sea level rise: As the global oceans absorb more of the excess heat trapped in the atmosphere by accumulating greenhouse gases, they also expand. That means that when storms come ashore, piling up ocean water in front of them, the overall storm surge will be greater in a warmer future.

While hurricanes are measured by the speed of their winds, the "storm surge is always the greater threat in a hurricane," Sullivan said. "It is the water that kills, not the wind."

Several recent storms, particularly Hurricane Sandy, have made that threat clear. Sandy brought 9.4 feet of surge to Manhattan's Battery Park, of which about 12 inches was due to sea level rise over the past century. NOAA has worked to make new maps that show specific storm surge watches and warnings, as well as more detailed, zoomable maps that show how high waters could get in a community.

"These will be maps that show you your neighborhood," Sullivan said.

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Whether or not any tropical storm or hurricane that forms during this season will hit the U.S. is something that scientists cannot yet forecast, though they are working on models that would help indicate what regions might be more likely to see a storm.

Storm activity in the main hurricane development region of the Atlantic is likely to be tamped down by the El Niño currently in play. El Niño is a climate phenomenon characterized by warmer-than-normal ocean waters in the central and eastern tropical Pacific. While that warmth helps boost Pacific storm activity, the extra heat transferred to the atmosphere leads to a domino effect that creates unfavorable conditions for storm formation in the Atlantic.

Specifically, it increases wind shear - change in wind speed or direction with altitude - which can strangle a burgeoning storm, and leads to a more stable atmosphere, the opposite of what a tropical cyclone needs.

This El Niño likely also played a role in keeping activity low last season, even though it hadn't yet fully formed. But it looks to be strengthening now, with a 90 percent chance that it will last through the summer, according to NOAA forecasters.

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Near-normal Atlantic Ocean temperatures will be another factor in keeping storm activity low, as warmer waters are better fuel for developing storms.

Officials are worried that the forecast for a below-normal season, along with the nine-year "drought" in major hurricane landfalls (Sandy was the equivalent of a Category 1 hurricane) will lead to complacency on the part of those living in vulnerable coastal areas. The last major hurricane to hit the U.S. was in fact in 2005 when Hurricane Wilmahit southern Florida in October of that year.

FEMA deputy administrator Joe Nimmich warned that people and communities still need to be prepared, even for storms that don't reach major status, since a tropical storm can still cause disastrous flooding.

"It doesn't take a hurricane to make a disaster," he said.

More From Climate Central:

Is Warming Changing Boundaries of Hurricane Season?

U.S. Hurricane Drought ‘A Matter of Luck' This article originally appeared on Climate Central, all rights reserved.

As seen from space, Hurricane Katrina takes aim at the Gulf Coast in 2005.

Although deadly, Hurricane Isaac scourged Louisiana with less ferocity than Hurricane Katrina did seven years ago. Katrina was one of American history's deadliest and costliest natural disasters. Part of what made Katrina such a tragedy was the inadequate emergency response from authorities. However, as intense as the outcry over the response to Katrina was, it pales in comparison to the repercussions of when one of history's deadliest storms struck what is now Bangladesh. Bangladesh was a part of Pakistan at that time, but the people of East Pakistan, as the region was called, suffered discrimination from the western portion of the nation and revolution was smoldering. The flames of nationalism and rebellion were fanned by the high winds of the massive Bhola cyclone which rushed in from the Bay of Bengal on November 10, 1970. The Pakistani government was criticized by locals and in the international media for failure to provide adequate disaster relief to East Pakistan, which may have contributed to the 300,000 to 500,000 people who perished in the storm and its aftermath. Soon after the cyclone, the storm of East Pakistan's outrage built into a war that tore Pakistan apart. The torment of war raged on until Bangladesh emerged as an independent nation from the flood of bloodshed that was the Bangladesh Liberation War. Throughout history massive storms have toppled human ambitions and left suffering and death in their wake. Particular natural disasters stand out from the line up of perpetrators as particularly devastating natural born killers.

The Day America Burned The wildfires that incinerated stretches of the American west this year were huge, but relatively few people lost their lives. On October 8, 1871 more people died in the flames of a wildfire than on any other day in recorded human history. On that day the Peshtigo Fire started in the forests of Wisconsin and was spread by a strong wind. The blaze quickly grew as it fed on trees left parched by a summer drought. The flames weren't extinguished until after they had snuffed out the lives of 1,200 – 2,500 people. The exact number is unknown because local records were also destroyed. The entire town of Peshtigo was consumed, leaving few to identify the charred corpses. On the same day, the Great Chicago Fire reduced much of the Windy City to ashes. Though Mrs. O'Leary's cow was later cleared of any culpability, the story of a kicking cow starting the fire became part of the legend surrounding the blaze that killed 300.

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Nature's Gas Chamber Other natural disasters can destroy whole towns at once too. Besides malaria, venomous snakes and leopards, the forest of Cameroon is also home to a lake that kills villages with its belches. Lake Nyos released an estimated 1.2 cubic kilometers (0.29 cu. mi.) of carbon dioxide and noxious sulfurous gases on August 21, 1986. As the bubble of heavier-than-air gas spread along the ground, approximately 1,700 people were suffocated along with 3,500 livestock. The killing cloud spread death up to 25 km (16 mi) from the lake. The lake's gas problem comes from an underwater magma dome that is constantly leaking carbon dioxide into the water. As the concentration builds, a disturbance in the lake's waters can cause the gas to be released in a suffocating explosion. Now, a degassing system siphon's the gas saturated deeper waters up to the surface, where the gas escapes in harmless quantities.

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4000 With One Bolt The Knights Hospitaller became the Knights of Rhodes after they lost control of Jerusalem to Muslim armies during the Crusades. They set up shop on the island of Rhodes in the 14th century by constructing a massive castle known as the Palace of the Grand Master of the Knights of Rhodes. The Knights also lost that stronghold to Muslim armies after the Turks conquered the islands and expelled not only the knights, but also the Greeks. Being expelled may have saved their lives. On April 3, 1856, a single bolt of lightning struck the steeple of the church attached to the palace. The Turks had been using the church and the storage area beneath the Palace as an ammo storehouse. When the fire found the gunpowder, an explosion leveled the 450 year old Palace and laid low 4,000 people. The Palace was rebuilt by the Italians in the early 20th century after they gained control of the island in 1912. The refurbished castle had the dubious distinction of hosting vacationing dictator Benito Mussolini after the Fascists rose in Italy.

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China Shattered by Quake Historical records in China extend unbroken for centuries. Included in those records are the body counts from some of the worst disasters in human history. An earthquake centered in Shaanxi province killed approximately 830,000 people on the morning of Jan. 23, 1556. In some areas, more than half the population was wiped out. One reason the toll was so high was that many residents lived in artificial caves dug into the soft soils of the area. The powdery soil collapsed in the quake, turning family homes into mass graves. Beneath those Shaanxi soils, the terracotta army of Qin Shi Huang, China's first emperor, may have been shaken from their slumber by the heaving of the earth around them and the misery of their country above them.

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China Drowned by Flood Floods have also terrorized the Chinese many times in the country's long history. Six of the ten deadliest floods in history struck the Middle Kingdom between 1887 and 1975. The worst may have been the flood of 1931. Estimates range as high as four million dead. The 1931 flood occurred after a two year drought ended. Heavy snows in the winter led into a rainy spring and even wetter summer during which seven typhoons drenched the land. The Yellow (Huang He), Yangtze (Chang Jiang) and Huai Rivers all flooded and inundated much of the country's cropland. Whole villages were washed away as dikes and levees failed.

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A Wave of Death Earthquakes and inundations can be deadly on their own, but together they pack a one-two punch of devastation. On Dec. 26, 2004, the third largest earthquake ever measured unleashed a wave that would wash away more lives than any other in history. More than 230,000 people died as the tsunami spread across the Indian Ocean from the quake's epicenter off the western coast of Sumatra, Indonesia. Fourteen countries were affected by the wave, especially Indonesia, Sri Lanka, India and Thailand.

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Ring of Fire For those countries that fall into the true ring of fire, the only man in black is the Grim Reaper, not Johnny Cash. The ring of fire is a line of volcanoes around the perimeter of the Pacific Ocean where tectonic forces make earthquakes and volcanoes an ever present threat. Indonesia shines like a jewel of molten magma set in the ring of fire. During the past 500 years, the area that is now Indonesia has suffered more deadly volcanic eruptions than any other place. An ancient eruption of an Indonesian volcano in the 400s AD may have darkened the skies over an already crumbling Roman Empire and led to crop failures. More recently, nearly 100,000 perished in the eruption of Mount Tambora in 1815. The eruption darkened the global sky and caused the Year Without a Summer, when chilly temperatures again led to failed crops in Europe. The island of Krakatoa exploded in a gigantic eruption in 1883 that ended 36,000 lives. Mount Kelut killed more than 5,000 in 1919. The same volcano had taken out 10,000 people in 1586.

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