As this is being written, hurricane Sandy is still moving in a mostly westerly direction after making a devastating landfall along the New Jersey shore. Also hard hit was New York, but the storm’s destruction is wide spread in the eastern third of the nation. The storm is huge. Satellite pictures show the storm influences an area from the east coast all the way to the Mississippi river, and from northern Florida to Canada. Its size is unprecedented. Besides the on-shore damage from wind and high seas, Sandy produced a wide swath of snow including blizzards in West Virginia and 60mph wind gusts in Chicago.
Yet Sandy started out as a mere Category I hurricane with sustained winds at 75 mph. That’s only a bit stronger than a tropical storm. How did this relatively weak hurricane turn into the monster it became? Several weather related conditions came together at just the ‘perfect’ time.
Hurricanes are born over warm seas. The warm water heats the air above it and the warm, moist air rises, similar to the way thunderstorms form over land. But over the ocean there are no obstructions to help dissipate the storm and so once set in motion the low-pressure area continues to ‘feed’ off the warm water. We can say then that the warm water is the ‘fuel’ that powers a hurricane. Hurricanes that follow the general pattern that Sandy was following usually turn north and then east in the Atlantic and when they do they encounter cooler water. With the loss of their ‘fuel’, they usually weaken and gradually dissipate. However because of an unusual wind pattern in the Jet Stream, Sandy found a new source of energy and continued on full strength.
The Jet Stream is the fast moving and continuous west to east flow of air at high altitude. It determines the path of storms across the country. So we know that a storm coming on shore in Oregon will likely be visiting us in a few days and then move on to the east coast. Usually the west to east Jet Stream pushes hurricanes away from the east coast. But this time an unusual ‘dip’ in the river of air developed over the eastern U.S. just as Sandy was heading up the coast. Instead of the typical west to east flow, this time the east side of the dip was more of a south to north flow which ‘pushed’ Sandy onto land instead of directing it out to open ocean. This is a highly unusual occurrence.
As Sandy moved north, the ocean water grew colder and so its ‘fuel’ source was gone. Yet in another coincidence, Sandy drew upon the temperature differential between colder air coming down from Canada and warmer air from over the subtropical ocean. Technically it was no longer a hurricane at this point, but rather an intense low-pressure area. Yet with this new source of energy the winds remained the same or even increased slightly, and the storm ‘stretched out’ into the behemoth it became.
The other bit of bad luck with this storm was it hit at high tide and during a time when the tide is higher than average. The powerful winds combining with the high tide created tsunami-like waves of water that over flowed ocean front barriers and flooded vast areas of metropolitan real estate.
In terms of dollars, the damage from this storm has been described as ‘incalculable’, the death toll in the dozens. Many people who ignored evacuation orders found themselves stranded in attics to escape the rising water. They just didn’t believe the storm would be as bad as it was predicted to be. Second guessing Mother Nature is not a good plan, and second guessing meteorologists who spend their entire careers studying weather related phenomena is not a wise move either.
The inevitable question becomes: Is Sandy proof of climate change, or just what happens when many weather related phenomenon come together at just the right time and place? Sandy is certainly unique to modern times, but as mentioned in other articles, the ‘proof’ is not so cut and dried. Meteorologists predict that because the atmosphere is heating up, these ‘once a century’ type storms will become increasingly common. It’s a warning, a wake up call, and as close to ‘proof’ as one can get, but there will always be those who don’t take the warnings seriously and end up holed up in the attic waiting to be rescued. Sandy should be a warning to us all, or put another way, how many Sandys will it take for Nature’s message to sink in?