NASA A handout picture shows Hurricane Sandy off the US east coast, with maximum sustained wind speeds of 140 km/h.

The name may be funny—Frankenstorm—but be advised: Hurricane Sandy is no joke. Over the weekend meteorologists were running out of frightening things to say about Sandy, which by the time it makes landfall on Monday evening—most likely in New Jersey—will almost certainly be the largest storm to ever hit the East Coast, with a reach that extends some 450 miles beyond its core. Sandy truly will be the perfect storm—not just because a hurricane is meeting a northern blockage that will fuel its strength as it hits land as well as another western storm system, but because Sandy is set to strike the richest and most populated part of the U.S. “We’re looking at impact of greater than 50 to 60 million people,” said Louis Uccellini, head of environmental prediction for the National Oceanic and Atmospheric Administration (NOAA). A drone strike couldn’t be better targeted to cause maximum damage than this storm.

(PHOTOS: Hurricane Sandy Ravages East Coast)

A NOAA video shows what’s happening as Sandy collides with the other fronts (h/t Andy Revkin):

[youtube=http://www.youtube.com/watch?v=OEY4s_D4xhU]

It’s not so much that Sandy is an incredibly strong storm, with winds at about 85 mph. NOAA’s Hurricane Research Division put the destructive power of Sandy’s winds at a modest 2.6 on a scale of 0 to 6. The real danger comes from the potentially huge storm surges the hurricane could cause along coastal areas. NOAA put the storm surge threat from Sandy at 5.7 on that 6 point scale—greater than any hurricane observed between 1969 and 2005, including Category 5 storms like Katrina and Andrew. NOAA’s National Hurricane Center says that “life-threatening storm surge flooding” is expected along the mid-Atlantic coast.

For coastal cities, such surges—amplified by the fact that Sandy will be hitting during high tide—could prove disastrous. Storm surges are expected to reach 4 to 8 ft., if not higher, as Sandy pushes vast amounts of ocean water onto the land. In and around New York City, it could be worse, with storm surges predicted to reach as high as 11 ft.—nearly a record—in northern New Jersey and Long Island Sound. Preliminary forecasts suggest that lower Manhattan could experience its highest waters since at least 1851.

That’s why Mayor Michael Bloomberg announced Sunday morning that the city would evacuate low-lying areas, meaning that some 370,000 people—a population equal to that of Minneapolis—may need to move. The city also shut down its subway, bus and commuter rail services, beginning at 7 PM on Sunday. (Buses were shut down two hours later.) That decision—also taken when Irene neared New York last year—was made to try to reduce the risk of damage to subway equipment in tunnels, which could flood depending on the extent of the surge. “I give a 50% chance that Sandy’s storm surge will end up flooding a portion of New York’s subway system,” wrote Jeff Masters of the Weather Underground’s Wunderblog.

(MORE: ‘Frankenstorm’: Worse Than Sum of Its Parts)

It’s not clear when New York’s subway service will be restored, but if the flooding is severe, it might be a long, long time. New York just barely avoided disaster during Irene in 2011—Klaus Jacob, a research scientist at Columbia University’s Earth Institute, noted last year that if the storm surge had been just 1 ft. higher, subway tunnels under the Harlem and East River would have been unusable for a month, at an economic cost of $55 billion. The threat to the subways is another reminder that the economic cost of a storm has as much to do with where it hits as it does with how strong the hurricane is in the first place.

And make no mistake: Sandy is a freak. While it’s not unheard of for hurricanes to form this late in the year—the actual Atlantic hurricane season extends another month—storms will usually be pulled out to sea by a semi-permanent low-pressure system near Iceland. But that’s not what happened with Sandy, as meterologist Eric Holthaus points out:

The coincidence of that strong of a high pressure “block” being in place just when a hurricane is passing by — in and of itself a very rare occurrence — is just mind bogglingly rare. It’s the kind of stuff that’s important enough to rewrite meteorological textbooks. The result: Instead of heading out to sea Sandy’s full force will be turned back against the grain and directed squarely at the East Coast.

(MORE: After Levee Blast, More Rough Water Ahead)

The sheer oddness of Sandy’s arrival begs the obvious question: Is climate change involved here? Many environmentalists certainly think so. But scientists are always reluctant to link climate change to any specific weather event, and the impact of warming on hurricanes have proved particularly difficult to untangle. The last Intergovernmental Panel on Climate Change (IPCC) report noted that scientists have “low confidence” in long-term increases in tropical cyclone activity due to man-made warming. It’s true that warming does increase the amount of moisture in the air, which can make storms rainier—just as we saw with Irene last year, and potentially with Sandy now. But don’t be fooled by cautious scientists—we can expect that global warming will likely bring about stronger and potentially more destructive storms and other natural disasters like Sandy.

What we know is that, climate change or not, big storms will happen—and if they hit populated areas, they will cause damage. The immediate challenge is to prepare for those disasters, and in the future, build societies and infrastructure that can be resilient to the sort of catastrophes that we know will continue to unfold in the future. Sandy killed at least 61 people as it made its way through the Carribbean—53 of them in the desperately poor country of Haiti, which remains consistently unprepared for natural disasters. Sandy will almost certainly cause billions of dollars of damage when it hits the East Coast. We’re unlikely to see a severe death toll, thanks to the fact that rich societies like the U.S. have gotten better at predicting and preparing for storms. (The famous 1938 Long Island Express hurricane, another historic storm, killed some 800 people in the U.S.—a death toll that would be impossible to imagine today.) As Sandy looms, let’s hope we’re ready.

MORE: Climate Change Equals Hot Summers. Case Closed.