Saturday, August 27, 2011

Irene NYC log

This is supposed to be a blog about the MJO, but as I am sitting in NYC during the onset of a weather event that's nearly unprecedented in living memory for this city, I'm hijacking it to put up a little log of that.

I have been following Irene since about Wednesday night. During that time the forecast has been remarkably stable. As the various models have moved the track either a little inland or a little further out to sea, the estimates of Irene’s intensity upon landfall in the NYC region have fluctuated between category 1 Hurricane and Tropical Storm, with the passage through our latitude occurring somewhere from a little west of the city to eastern Long Island. Tracks either further inland or far enough east that Long Island and New England are spared have looked unlikely from the start. The intensity forecast for us remains in the tropical storm - category 1 range (despite the fact that the intensity with which it recently made landfall in North Carolina has ended up lower than had been forecast a day or so before).

In any case we are almost certain to get an awful lot of rain. It is already raining now (11:30 AM, when the storm center is still down in North Carolina), from what looks to be a far outer band of Irene.

The storm surge risk is real as well. Even if the intensity stays on the lower side of the forecast range, the large size and slow motion of Irene mean that the wind will be pushing on a large piece of oceanic real estate for a long time, which means more water pushed up into New York harbor. Because we have a spring tide now, the high tide will be about as high as it ever gets. So the magnitude of the storm surge depends a lot on its timing - whether it arrives at high tide or low. Some detailed accounts of the evolving forecast of this are here. In any case it seems to me that the city is doing the right thing evacuating zone A (but not B). Stopping the subways seems the right move too, though doing so at noon seems a little over-conservative. The first concern as I understand it is wind on the elevated lines, but it seems pretty likely that there will be flooding in some underground lines from rain, storm surge, or both.

Our local grocery store very crowded, with long lines and some staples running out. The whole neighborhood seems pretty much out of batteries.

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