Understanding The Fear Of Frankenstorm

R. is not persuaded:

Are you in on this one ... with your forecasting work? There seems to be a lot of hysteria building on the web about this hurricane. how come?

I reply:

Ah, yes, Frankenstorm! It’s mostly because, as Hurricane Sandy weakens and becomes extratropical over water, it collides with a strong cold front over the eastern U.S., strengthening again, with maximum low pressures forecast to reach depths that have never been observed – EVER! Even in the Long Island Hurricane of 1938 – the gold standard of worst-case East Coast weather!

I’m hoping that it won’t be that bad. Today’s forecast didn’t look as bad as yesterday’s forecast, so maybe there’s hope after all! But certain places, like New Jersey, might get hammered no matter how things transpire.

R. replies:

what I'm not getting is why the great concern when it is cat 1 today, expected to weaken, might then strengthen when it merges with the other fronts, and the prediction is for 40-60 mph winds. That's very strong winds, but not hurricane force. The baro goes really low, but why is that a particular concern for damage, loss of life, etc. How does this outdo Andrew and Katrina? Is it just a slow weather month?

Thanks for any insight you can offer.

I reply:

Here’s some of the press freakout.

Part of the trouble is that the area that will experience high winds is very broad – broader than a hurricane by itself is capable of reaching. Another is that it is highly urbanized, and a third is that trees still have lots of leaves on them, and so are unusually vulnerable right now to damage. The geography of Long Island Sound is perfect for a storm surge as well, and so that’s a fourth concern.

The June 2012 derecho demonstrated that the infrastructure of the NE is now too antiquated to maintain First-World civilization under challenging conditions. It took about a month to restore power in some areas from all that. This storm might be worse than that one was!

So, there are a lot of valid concerns.

R. replies:

I am beginning to believe that the problem is the winter storm, not the hurricane. It seems to me the hurricane's role is to strengthen the winter storm and they are worried about ice, freezing rain, storm-force winds breaking trees, lots of rain producing flooding inland, and the high tide/weak hurrican combo causing flooding along the shore.

I reply:

Yes, that’s the package! The hurricane adds in a lot of moisture, heat and its pre-existing cyclone that just helps accelerate things.