The eastern US is bracing for hurricane Sandy, which is expected to make landfall next week. The storm looks set to be a record-breaker, and could cause severe damage. New Scientist breaks down what we know about the storm, and what it is likely to do.
Where is hurricane Sandy?
formed in the Caribbean, north of Panama, and at the time of writing was . It is currently a , the weakest kind, with maximum wind speeds just under 130 kilometres per hour.
According to of the National Ocean and Atmospheric Administration (NOAA) National Hurricane Center in Miami, Sandy was moving towards Florida but is now expected to parallel the east coast of the US, before turning west and making landfall sometime between Monday and Wednesday next week.
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狈翱础础鈥檚 says he is currently 90 per cent sure that the storm will indeed make landfall, rather than dissipating over the Atlantic.
Where is it going to hit?
It鈥檚 too soon to be sure. NOAA has forecasts of the path Sandy will take, but four or five days from landfall, these can only predict the location over a range of about 320 kilometres. As a result, the east coast from the Carolinas all the way to Canada is at risk. The forecast accuracy will improve over the weekend.
I鈥檝e heard that it will become a 鈥淔rankenstorm鈥�. What does that mean?
Hurricane Sandy looks set to merge with two other weather systems, which will intensify the storm. A winter storm moving in from the west, and a cold system from the Arctic, are both expected to collide with Sandy in the coming days.
The combination of the three systems will create a much more dangerous storm. Hurricanes are low-pressure systems, and according to 狈翱础础鈥檚 Hydrometeorological Prediction Center, than any known east coast storm. On that measure, it could become the most intense storm on record.
What will happen when Sandy hits the coast?
Sandy鈥檚 extreme low pressure will create a storm surge: low air pressure 鈥渟ucks鈥� the ocean up into a mound that then floods the coast. The precise location of the storm surge is particularly difficult to predict. The surge will be exacerbated by the full moon, which will cause a high tide. 鈥淪omebody is going to get a significant surge out of this system,鈥� says Franklin.
The storm will also bring high winds and heavy rain. In Virginia and the Appalachians, the rain is expected to turn to heavy snow. Coastal regions could see as much as 25 centimetres of rain, while further inland it could be as little as 12 centimetres. Uccellini says the heaviest rainfall is likely to be in a belt running from Delaware through Maryland and Pennsylvania.
How will it compare to recent storms?
Sandy could well be more damaging than 2011鈥檚 hurricane Irene, which was one of the costliest hurricanes in US history. The circle of storms around Irene partially broke up, producing a patchy wind field that caused less damage than might have been expected, but Franklin says that鈥檚 unlikely to happen to Sandy.
鈥淲e鈥檙e looking at something bigger than Irene,鈥� Franklin says.
The storm is likely to continue for several days once it hits. Uccellini says there are three 鈥渂locking patterns鈥� in the jet stream above the US, which are causing weather systems to move slowly. As a result, Sandy will spend longer over the east coast than it otherwise would.
Has anything like this happened before?
In 1991, a storm approached the US east coast from the north-east and merged with hurricane Grace. Known as the Perfect Storm, the merged system caused extensive coastal flooding and enormous waves in the Atlantic.
鈥淭o some extent, it has similarities to the conditions surrounding the Perfect Storm,鈥� says Uccellini. However, Sandy is actually a stronger storm than Grace.
What should I do to stay safe?
You can follow Sandy鈥檚 online. Anyone in the path of the storm should consult the , which will .
