Why strong storms could be even more dangerous

Sandy, a superstorm of unusual ferocity and scale, this week wreaked havoc on much of the east coast of the United States and Canada. There was inevitably major disruption to transport (around 20,000 flights alone were cancelled), more than 60 people were killed (adding to the more than 70 earlier deaths in the Caribbean), and more than eight million were left without power.

Overall damage and cost of clean-up is estimated, by some, at $30-40 billion, and New York (facing its worst crisis since 9/11) has been declared a major disaster area by President Barack Obama. Alarmingly, in New Jersey, the Oyster Creek nuclear plant was put on alert after rising flood waters threatened the cooling of its spent uranium fuel rods, echoing the Fukushima disaster in Japan.

Although the storm was downgraded from a hurricane to a post-tropical cyclone just before making landfall, the geographic spread remained around 800-900 miles wide from the Atlantic Ocean to the Great Lakes and the Midwest. Moreover, some winds remained sustained at around 80 miles per hour.

Normally, if storms move inland they lose strength rapidly. However, in this case, Sandy met a cold front to the northwest and high pressure to the northeast. It is because of these interactions that the winds and rain extended over such a wide area.

Sandy has been called, by some, the "perfect storm" and the "storm of the century." But there are reasons to believe that strong storms could be even more dangerous in the future.

As has already been seen in Asia, the tracks of such big storms may be changing as wind patterns are affected by climate change. It is also anticipated that cyclones and hurricanes will become stronger in areas where ocean surface temperatures are increasing, such as parts of the Gulf of Mexico, where many storms originate from which subsequently batter North America.

While Sandy is an unusual storm, the good news is that computer forecasting models have been quite good. It is remarkable that airlines, in particular, have relied so much on these forecasts to make their cancellation plans.

This is a quite different experience from the previous "storm of the century" in March 1993 in the Americas when airlines did not make good use of the-then computer forecasts.

The breakthrough in computer forecasting of tropical cyclones and hurricanes happened in 1993 thanks significantly to Professor Jonny Chan, working with the UK Met Office when I was director-general there. This breakthrough allowed for a very wide area of interaction between cyclone winds and the general circulation over 500 miles away from the storm center. Fittingly, Professor Chan, who teaches at City University of Hong Kong, now chairs the World Met Organization committee on tropical cyclones.

With improvement of forecasting of the track of storms and high winds, there has been steady improvement too in forecasting waves and the tidal surge in the shallow waters along the coastline. Tidal surges often lead to inland flooding, which is exacerbated by the breakdown of coastal defenses.

In the United States, this week’s storm surges have driven sea water deep inland. In Manhattan, for instance, water levels reached some 14 feet, exceeding previous highs by over 4 feet.

Sea surges also reportedly broke through a flood defense levee in New Jersey with five 5 of water. For some, this has revived memories of Hurricane Katrina and the disaster in New Orleans in 2005.

Dutch and U.S. researchers at Delft University of Technology and Notre Dame University have played a key role in the improvement of forecasting of the track of storms and high winds, and in forecasting waves and the tidal surge in the shallow waters along the coastline. Both Delft and Notre Dame have developed remarkable simulations showing in advance all the various ways in which flooding moves through built up areas, sometimes with dangerously high currents.

In response, some are already contemplating major new innovations to the built environment. This includes, for instance, houses with collapsible ground floor walls to reduce the speed of the maximum water currents from flooding.

With strong storms potentially becoming even more dangerous in the future, this and other research could be key in equipping and preparing us for the intensified challenges that will ensue.

© Japan Today