Skyscrapers Pose Danger in Hurricanes

When Hurricane Irene began tracking toward New York City, officials feared the worst. In a city full of skyscrapers a hurricane can become a bigger instrument of destruction. Flying glass as windows blow out create dangerous projectiles littering the streets. And the space between highrise buildings which turn into wind tunnels on a windy day can spin up debris that does much more damage.

Thankfully, that didn’t happen in New York. This time. But it did happen further north in Montreal, Quebec. By the time Irene crossed the Canadian border she was downgraded to a post-tropical storm. But she still blew into the French-speaking city with powerful winds.

And there, 300 miles north of New York and with much weaker winds, skyscraper windows blew out and fell to the street. In one building windows on the sixth and 19th floors crashed to the ground. Because it was raining so hard and people were warned to stay indoors, no one was injured. But on a regular day, this heavily trafficked street would have been bustling with pedestrians.

When the National Hurricane Center measures wind speeds for a hurricane, they are the speeds at ground level. In a vertical city like New York, those speeds increase rapidly with altitude. For example, wind speed of 60 miles per hour turn into 90 mile per hour winds on the 25th floor and get stronger the higher you go.

Hurricane Irene hit New York City with winds clocked about 60 miles per hour, too slow to even be considered a hurricane. Remember, those are sustained winds. Gusts blew much higher in short bursts.

Tropical Storm Irene didn’t blow windows from skyscrapers in New York because the storm was weaker than predicted when it hit the Big Apple. But meteorologists recognized her damaging potential.

According to CNN meteorologist and severe weather expert Chad Myers Irene’s pressure was still so low when it reached New York that it still had the necessary energy to do some real damage. He says it was just luck that avoided a glass-shattering disaster.

Even though Irene won’t remembered for her winds, tall buildings in hurricane zones generally come built with windows that can withstand pressure and winds associated with a Category 3 hurricane. But a Category 3 on the ground can be a Category 5 a few hundred feet up.

Tropical Storm Irene entered Manhattan with sustained winds of 60 mph. That means those same winds were 110 mph on the 100th floor of a building.

Cover photo of Houston following Hurricane Ike