Friday, August 26, 2011

The Adjustment

Irene will peak over today, then, begin to weaken as a significant portion of the storm goes over land. It is a slow moving storm, which can create more damage, but also weakens it over the long term. The constant churning of the ocean brings up deeper, cooler water, which inhibits the heat engine that a tropical cyclone depends upon. The slower the storm moves, the more cool water is worked to the surface. Additionally, the storm is working towards cooler waters, and that will influence it's strength.

The land will do much to disturb the storm's structure, especially as it is moving fairly slow. My prediction now is that Irene will hit the metro area (that includes Jersey and LI) as a low level hurricane, but quite possibly as a strong tropical storm. Now, what matters most is exactly which direction it moves. To the west of NYC, and we will see more wind and more coastal flooding. To the east and we will see less wind, less coastal flooding (but some!) and more rain flooding. New Jersey, the Hudson Valley, CT, etc. should expect anywhere from 5 to 12 inches of rain depending on the speed of the storm at landfall. Add those quantities of rain to what these areas had two weeks ago, and we have a scenario for some heavy flooding.

Subways were out of service on the morning of August 9, 2007 due to rainfall from one thunderstorm. We should expect the same, or that they will curtail service before it happens. Certain bus routes will be shut down, if not all, by Saturday night. The Gowanus area should expect serious street flooding as happened during that one thunderstorm in 2007. Other areas should expect the same. The Belt Parkway will have closures due to rain/coastal flooding. Certainly other areas will have the same problems. Roadway storm drainage is calculated to handle set volumes due to cost constraints. The price we pay for this is flooded roadways.

Avoid parking your car under large trees and don't sit in them. Large limbs will fall. Trees are not likely snapped at the trunk like they are in tornado winds (which are tightly wound and almost instant), but the winds will thrash the trees until some give way, often due to the water-logged soil. However, canyons of buildings facing the right direction will funnel the wind and increase its potential for local damage.

Power may go out, but not for very long. Cell phone coverage may be intermittent. Piped gas could be affected. Water may need boiling if water mains become inundated with combined sewage overflows, which mix storm runoff with sewage because the system is not designed (cost, age, etc.) for these potential water volumes. This is why we buy bottled water before tropical storms. Storms that are in a category beyond what our infrastructure was designed specifically to handle render our infrastructure useless. This is what we prepare for in a city.

Not because it is the apocalypse. Not because of what happened to New Orleans. This won't be that. Irene is no Katrina. It's simply because we haven't built around the conditions of tropical storms which are rare in NYC, and often overshadowed by Nor' Easters.

Hurricane Bertha took a similar course in 1996. After hitting the Carolinas, it diminished rapidly. Maybe it is 1999's Hurricane Floyd that Irene will emulate, with a path that is uncannily similar to Irene's projected path. Floyd was a lot stronger in its Bahama cycle, but otherwise parallels Irene. Do you remember Floyd? Vaguely? 


Projected path of Irene


  1. Nicely explained for non-meteorologists.
    Good luck!

  2. I'm stuck in Indianapolis, worrying about Michael back home. Your post is so well-reasoned and rational, it made me feel much better. Thanks, Frank.

  3. Glad to help. All the news drives me crazy. And a little bit of a hurricane geek since I was a kid.


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