“The climate has shifted to a new state capable of delivering rare and unprecedented weather events.”
—meteorologist Jeff Masters

The eastern half of North America is preparing for one whopper of a storm. Hurricane Sandy is expected to be a major storm that will cost Jamaica, the Bahamas, the US and Canada billions of dollars in recovery. The community of meteorologists who are following it are describing it in ways that are unheard of, all the more surprising since we dealt with Hurricane Katrina only seven years ago.

Terms like “freak,” “unprecedented and bizarre,” “the perfect storm” and “frankenstorm” have all been bandied about. So what the heck is so unusual about Hurricane Sandy to earn all of these extreme epithets?

One factor is that Hurricane Sandy started as a tropical storm from the Caribbean but managed to collide with an Arctic jet stream that came through the US. As a result, this can lead to a significant drop in pressure, allowing a category 3 or 4 hurricane to develop which means winds in excess of 115 miles per hour.

Of course, another factor is climate change in general. Kevin Trenberth, former head of the Climate Analysis Section at the U.S. National Center for Atmospheric Research, states that all superstorms “are affected by climate change…The air is on average warmer and moister than it was prior to about 1970 and in turn has likely led to a 5–10 % effect on precipitation and storms that is greatly amplified in extremes. The warm moist air is readily advected onto land and caught up in weather systems as part of the hydrological cycle, where it contributes to more intense precipitation events that are widely observed to be occurring.”

So what does this mean for North America in the next few days? (Apart from a colder and messier Hallowe’en night which seems to be the biggest concern for my kids, I mean?) Well, at least 69 people have already been killed by the storm in the Caribbean and the Bahamas. The US east coast is going to be hit pretty hard, from the mid-Atlantic to New England where it will have a significant impact on a very densely populated part of the country, including major cities such as Boston, New York, Washington, Baltimore, and Philadelphia.

New York City is expected to shut down its subway, train and bus service to prepare for the deluge. New Jersey was shutting down bus, rail, and casino services. The White House expects the storm will disrupt fifty million people, much of that disruption occurring in the transportation sector. More than 700 flights were cancelled yesterday and about 2,500 were already cancelled for today. More than 400 flights were cancelled in Toronto alone.

Twelve inches of rain are expected in some regions, with heavy snowfall in some of the colder regions. One property of the storm that makes it unusual is how wide it’s going to be, more than one thousand miles in diameter at its widest point. Because of this, weather forecasters predict the following: “Given the large wind field associated with Sandy, elevated water levels could span multiple tide cycles, resulting in repeated and extended periods of coastal and bayside flooding.”

Hurricane Sandy could be the largest storm to hit the US ever according to the National Oceanic and Atmospheric Administration’s (NOAA) website. The real question is whether this is a once-in-a-generation kind of Frankenstorm, or whether because of climate change we’re going to be seeing more and more of them all in the coming years.

Sadly, the science would predict that Sandy is indeed the new normal. We’d better get used to it because ignoring global warming and climate change won’t make their consequences go away.