Wednesday, August 24, 2011

Hurricane Irene May Skirt Carolina Coast, Target New York City

And then visit the President and Michelle on Martha's Vinyard.
Here's the current 5-day forecast, more on New York Hurricanes below the map.

Figure 3 Official track forecast of Irene at 2AM EDT.

The 1821 Norfolk and Long Island Hurricane is one of two hurricanes in recorded history to have directly struck what is now modern New York City (the other was in 1893).

The hurricane struck the city on September 3, 1821; it is estimated to have made landfall at Jamaica Bay.
Though the hurricane struck at low tide, it produced a storm surge of over 29 feet (9 m) along several portions of the New Jersey coastline, causing significant overwash.

When finally the storm reached New York City, it caused widespread flooding as far north as Canal Street.

Back in 2005 New York Press published an interesting piece looking at a hypothetical strike:
Experts say it's only a matter of time before a major hurricane

...A hurricane like this one can usually be counted on to curve eastward and die a harmless death over the Atlantic. But with a large area of high pressure hovering just off the east coast, the computer models at the National Hurricane Center in Miami are largely in agreement: This one is heading north, tracking a direct hit on New Jersey somewhere north of Atlantic City. Like the legendary "Long Island Express" of 1938, the fastest-moving hurricane ever recorded, it's moving quickly.

While no human or computer can ever be completely sure what a hurricane is going to do, this is looking like a worst-case scenario for New York City, the kind of scenario "that gives emergency managers serious gastrointestinal distress," says Lee. Because of its counter-clockwise rotation, the right side of a hurricane is the most powerful part of the storm. The right side of this storm is fixing to land a haymaker on New York Harbor. If it makes landfall during high tide, the devastation will be unprecedented.

With the storm expected to hit within 24 hours, Mike Lee is in constant communication with Mike Wyllie, meteorologist-in-charge at the National Weather Service's New York office in Upton. The OEM's emergency operations center, meanwhile, is buzzing, while the mayor and his chiefs are hunkered down in the situation room. They have an incredibly difficult decision to make, a decision that has never before been made in New York City. They are preparing to order the evacuation of 900,000 New Yorkers whose homes are in the path of catastrophic flooding in the event of a category-4 hurricane. They will provide shelter for nearly a quarter million. And while the storm is still far enough away that it could drift off course and miss New York City completely, a full evacuation may take up to 18 hours. They need to decide now. The fact that a mayoral election is only two months away doesn't make the decision any less complicated. An unnecessary evacuation could be a political catastrophe.

Though it sounds like science fiction, the above scenario is all too plausible. "Try to tell someone in Sheepshead Bay that they have to evacuate immediately because within the next 24 hours they'll have 30 feet of storm surge on their neighborhood," says Mike Lee, before pausing to let you think about three stories of ocean water roiling through your own neighborhood. "They'll laugh at you—absolutely laugh at you," he says. "I mean, I barely even believe it."

I met Lee at this year's Long Island/New York City Emergency Management conference and spent some time with him at the OEM "bunker" in Brooklyn. It turns out that the region's emergency managers aren't only worrying about terrorism these days. The big topic of discussion at the Melville, Long Island, Hilton was hurricanes. And the strong consensus is that the metropolitan region is due for a big one. Overdue, in fact.
The 1938 Long Island Express, a borderline category-4 hurricane that plowed into West Hampton, causing widespread death and devastation across New York, New Jersey and New England, was the last major hurricane to hit the region. Statistically speaking, "a storm of that magnitude may repeat every 70 to 80 years or so," Lee says. "So, do the math. Whether it happens this year, next year, or in five years, it's going to happen." And with this year's hurricane season forecasted to be even busier and more dangerous than last year's record-setter, "It's just a matter of time," Lee says.

Though it is rare for big hurricanes to hit the New York metropolitan region, there are a variety of "oceanographic, demographic and geologic characteristics that greatly amplify any hurricane" that comes our way, according to Nicholas Coch, a professor of coastal geology at Queens College. In many ways, Coch explains, "The New York City area is the worst possible place for a hurricane to make a landfall."
New York's first vulnerability is psychological. This is a city where children playing in the dirt are told by their mothers to "get up off the floor." We tend to forget that we have any connection whatsoever to the natural world. The vast majority of the city's eight million inhabitants simply have no idea that a hurricane can happen here.

"We live in a complacent coastal city," Lee says. "A lot of people don't even think that there are beaches here," never mind 478 miles of coastline. In fact, New York City is behind only Miami and New Orleans on the list of U.S. cities most likely to suffer a major hurricane disaster. Compounding the problem is the fact that many of the New Yorkers who lived through 1985's Hurricane Gloria believe they've experienced the worst of what nature has to offer. "That wasn't a hurricane," meteorologist Wyllie says. The storm was billed as a category-2 that weakened before it hit and came in at low tide. "Gloria was nothing."

New York's second vulnerability is demographic. During the decades of calm between major hurricanes, the city grows and forgets. During the great hurricane of 1821, only 152,000 people lived in New York City. When the next major, direct hit came in 1893, the city's population was 2.5 million. At the time of the 1938 storm, Long Island wasn't a densely populated suburban sprawl; it was a rural home for oyster fishermen, potato farmers and wealthy industrialists. The same storm today would wreak incredible havoc. AIR Worldwide Corporation estimates $11.6 billion in New York losses alone.

More than 20 million people live in the greater metropolitan region. Many live on coastal land, reclaimed swamp and barrier islands. Much of Lower Manhattan is built on landfill. Places like Rockaway, Coney Island and Manhattan Beach "are stretches of land that nature has created to protect the mainland from hurricanes," Lee says. "In our civilization this is also the most desirable land to develop and build on. We're not going to undevelop it. So we now have to deal with the threat."

Coch, the six-foot-seven-and-a-half professor once nicknamed "Dr. Doom" because he was the first scientist to widely publicize New York City's hurricane history and vulnerabilities, put it more poetically in a 1995 New York Times interview: The only difference between now and then is that "now we have millions of people to offer the God of the Sea."

New York City's biggest vulnerability is the most unyielding geology. The New York bight is the right angle formed by Long Island and New Jersey with the city tucked into its apex. "Hurricanes do not like right angles," Lee says. "[They allow] water to accumulate and pile up."

Couple this with the fact that New York resides on a very shallow continental shelf, and as a big storm pushes north, New York Harbor "acts as a funnel." As storm surge forces its way into the harbor and up the rivers, it has nowhere to go but onto land. New York City, it turns out, has some of the highest storm-surge values in the country. "When we see a category-3 storm making landfall in Florida, it may only have a 12-, 13-foot storm surge," Lee says. "For us here, a category-1 storm can give us 12 feet of storm surge."
Storm surge is the dome of seawater that is lifted up and pushed forward in front of a hurricane. It acts almost like a mini-tsunami, causing sea levels to rise rapidly and violently. Most people believe that high winds and rains are the main dangers of a hurricane. In fact, inland flooding caused by storm surge is the big killer. In 1821, stunned colonial New Yorkers recorded sea levels rising as fast as 13 feet in a single hour at the Battery. The East River and Hudson Rivers merged over Lower Manhattan all the way to Canal Street. According to Coch, the fact that the 1821 storm struck at low tide "is the only thing that saved the city."

To get a sense of the damage that storm surge can do to New York City, call 311 and ask them to send you a full-color copy of the New York City Hurricane Evacuation Map. It is a truly mind-boggling document. If a storm like the Long Island Express makes a direct hit on the city, everything below Broome Street will be inundated, some parts under as much as 20 and 30 feet of water. Chelsea and Greenwich Village are completely flooded, with the Hudson spilling over all the way to 7th Avenue. Likewise, the East River and East Village become one, with ocean water surging all the way to 1st Avenue. If you haven't evacuated before the storm, forget it. During the storm, Manhattan's east- and west-side highways vanish. Tunnels and bridges become unusable.

The outer boroughs also get hit hard. Opposed to that new Ikea being built on the waterfront in Red Hook? Don't worry. There's a decent chance it won't be there after a moderate-size hurricane. Residents of Williamsburg-Greenpoint should seek out a male and female of each species and get in their arks. In a kind of one-two-punch effect, a major hurricane will push ocean water down from the Long Island Sound into the Upper East Side, South Bronx and northern Queens, flooding those areas severely. Vast stretches of southern Brooklyn, Queens and Staten Island will be devastated. The map shows Atlantic Ocean storm surge reaching as far inland as Flatbush, just south of Prospect Park, with 31.3 feet of water atop Howard Beach.
"A lot of people say, 'How can you come up with these numbers? Thirty feet, that's ridiculous. It's science fiction.' Actually," Lee says, "It's science fact." Hurricanes in the southern U.S. have proven the Army Corps of Engineers' storm-surge calculations to be accurate within a few inches.

For a taste of what will happen to the city's infrastructure, we can look at the damage wrought by the great nor'easters of the early 1990s. During those storms, the L train had to be backed out as the 14th Street tunnel began filling with water, and the FDR highway was so badly inundated that 50 motorists had to be rescued by dive teams. In the event of a direct hit by a category-3 hurricane, surge maps show that the Holland and Battery Tunnels will be completely filled with sea water, with many subway and railroad tunnels severely flooded as well. The runways of LaGuardia and JFK airports will get flooded by 18.1 and 31.2 feet of water, respectively.

Then there are the winds. The city's two million trees will be a huge problem. "New York City's trees haven't been stressed in years except for an isolated severe thunderstorm or two," Wyllie says. They've had plenty of time to grow and wrap their roots around underground phone, electric, gas and water lines. As they are uprooted in the heavy winds, a lot of infrastructure both above and below ground is going to get wrecked.
As for skyscrapers, "The impact of catastrophic winds on high-rise buildings is still a little vague," Lee says. "We don't feel we have enough data on that."

We do know that hurricane wind speeds multiply at higher altitudes. At 350 feet, the height of high-rise buildings on the Battery and the towers of the George Washington Bridge, hurricane winds will be twice as fast as they are on the ground. Newer, glass-skinned towers are not likely to do well in those conditions. Neither will human beings caught outside amidst flying debris. To give a sense of the unbelievable force of hurricane winds, Lee shows a photo from one of the four storms that struck Florida last year. It depicts a blunt piece of two-by-four driven straight through the trunk of a palm tree.

"It would be nasty," Wyllie agrees. "If you get sustained winds going 80 to 90 miles per hour in the city—whoa, you can't believe the destruction. We've never seen that. And as you go up 200, 300 feet," he considers that for a moment. "That'll be 100, 110 mph winds. Watch out."...MORE