North-East Winds A-Blowin’

The big storm of 2012 (at least, we hope it’s the biggest we’ll see this year) is approaching the New York City area, and though no one can predict in detail how bad it will be and for whom, there’s no question that with so much energy to play with, post-tropical quasi-hurricane quasi-nor’easter Sandy (also called “Frankenstorm” in honor of the Halloween holiday) is going to hit some of us very hard in the northeastern United States.  Not that it will be a disaster everywhere in the region.  With hurricane Irene last year, some areas just had a bit of wind and rain, while others had tremendous flooding that wiped out towns and roads and houses and history… and a few dozen lives, too. It will likely be the same this time.

How unusual is this storm?  Several weather forecasters have been quoted as saying that their supercomputer-based forecasting tools, which predicted Sandy to strengthen and become a monster in size, were doing things they’d never previously seen them do.  Right now, all you have to do is look at the weather map — the fact that there are tropical force winds extending over several hundreds of miles, and at the fact that the pressure of the atmosphere at the core of this storm is around 946 millibars and falling — to know there’s a lot of energy in this system that has to go somewhere, and is going to be taken out on somebody.   Although this is a Category 1 hurricane in terms of its fastest winds, 946 millibars is what one expects for a strong Category 3 hurricane; 1000 is average atmospheric pressure, and the mid-800s is about as low as it ever gets.  By comparison, the great blizzard of 1993 had a central pressure of about 960 millibars.  The Perfect Storm of 1991 (also a nor’easter-hurricane hybrid, like Sandy) had a central pressure of 972 millibars.  Anyone who thinks Sandy isn’t a dangerous storm hasn’t read enough history.

I’m amazed at how often I hear New York City dwellers make fun of the weather prediction folks and the politicians for having advertised Irene as a dangerous storm, just because it turned out to be rather uneventful in the city proper.  This really involves a misunderstanding of the strengths and weaknesses of weather forecasting.  When the experts make predictions about weather, those predictions always come with the implicit caveat, one that everyone should be aware of, that weather prediction is neither an exact science nor a locally precise one.  It’s increasingly possible to predict general things for regions, such as that the weather in the northeast is going to become potentially very dangerous, that wind gusts will likely exceed 80 miles per hour in some places, and that it is likely that some locales in the northeast will suffer heavy damage.  But forecasters cannot reliably predict specific things for localities, such as whether the borough of Brooklyn will get 60 mile per hour winds and 3 inches of rain and a 5 foot storm surge — that’s more detailed than current scientific knowledge and technique permits.  Predictions with so much detail do get made — in fact you can look at the current prediction for New York City here — but one has to understand that such details are very uncertain, and are useful mainly for general guidance.  Fortunately, with somewhat more accuracy, it’s possible to predict the likely range of specific things: in particular, in this week’s storm, around Long Island and New York City the storm surge could perhaps be as bad as 11 feet, but is very unlikely to be worse than that.  The ability to predict a worst-case scenario saves many lives, by allowing policy-makers to focus on lives and property that are in the worst danger.

Forgotten in all the scorn that is heaped on those who predict the weather and often get the details wrong is how many lives weather forecasters save by getting the rough picture correct.  After all, they predicted that Irene would pass very close to the New York City area — and it did.  And here’s Sandy, whose potential to hit the northeast coast, as a very unusual westward-traveling (click here to see why) October hurricane, was first noted by the weather forecasters almost a week ago!  This forecast has become increasingly certain as days have gone by, and now all the forecasting methods agree that this will occur.  One must not lose sight of the fact that this achievement is astounding!

Consider that in 1938 a more powerful hurricane, sitting roughly where Sandy is now, suddenly and unexpectedly accelerated northward, and without warning blasted across Long Island and into the state of Rhode Island, with a massive storm surge and very strong winds that left over 500 people dead on what was expected to be a normal afternoon.  With modern methods of weather prediction, the potential for that northward lurch would surely have been known, and many of those lives would have been saved.

And without those modern methods, we would not have been known that today’s Hurricane Sandy would cease yesterday’s northeastward motion, and turn instead sharply to the northwest.  Instead of preparing last night with mandatory evacuations from low-lying areas, the shut-down of transportation systems, and cancellation of school in large sections of New York, Connecticut, New Jersey, Pennsylvania, Delaware and Maryland, we’d all be waking up in New York and its environs expecting a more or less ordinary rainy Monday morning, nonchalantly grabbing our umbrellas and putting raincoats on our kids — and we’d be completely unaware of the impending flood-tides and violent winds.

I can’t resist pointing out that for the lives saved today and tomorrow, we can thank investments in scientific research over the past century.  It is physics that provides the tools for our understanding of how weather works, and developments in physics underpin both the devices used to measure the weather and the computers used to predict it.  We should remember that advances in hurricane forecasting didn’t just fall from the sky, or blow in off the ocean in a strong wind.

19 responses to “North-East Winds A-Blowin’

  1. A meteorologist, I couldn’t have said it any better myself. Excellent article!

    This storm is indeed one of the strangest, if not the strangest, I have seen in my career (though I hasten to add that I’m a researcher, not an operational forecaster). It’s not unusual for a hurricane to transition from a tropical cyclone to an extratropical one (it happens all the time). But, this usually always means overall weakening, but in this case the storm is intensifying rapidly while making this transition, due to nearly perfect timing as it approaches the upper-level trough to its northwest. In addition, it’s still maintaining enough of its tropical characteristics to allow for much more rainfall than you would otherwise see. This will be a storm that will be studied for quite a long time after it’s gone.

  2. You are starting to make an impression with your views outside of your immediate surroundings, Mr. Strassler. First, a crystal clear Higgs explanation (with a very survivable math) and now weather and the importance of research! Thank you from many of the other physicist around the world. Greetings from Mexico.

  3. It is amazing that this storm is striking the Northeast almost exactly 1 year to the day of the freak October 30, 2011 snowstorm. In the Monadnock region of southwestern New Hampshire, where I live, we had 2 feet of snow.

    Yes, forecasting is remarkably accurate nowadays. When I used to go to sea for research cruises in the 90s and early 2000s, we relied on these forcasts to steer clear of inclement weather.

  4. A terrifically clear blog that had me reading from the start to the end. Mind you I need to read it again as it is fascinating, scary and thought provoking. Stay safe is the motto of the day I think…..

  5. I’m glad the DC area learned their lesson that it’s better to be overprepared than underprepared in these kinds of situations, especially after last year’s “Commute from Hell” during which many commuters from DC, Maryland, and Virginia were stuck on the roads until midnight trying to get home. Better safe than sorry! I’m home from work today because my office follows the OPM’s closing schedule, and even though it just looks like a regular ol’ rainy day out there, I’m not keen on driving home in it at 6pm when it gets real.

  6. Sorry to be off topic, but I was wondering when you might get around to writing the follow up to your excellent post “How Big Could an Extra Dimension Be?

    So far here in Keene, NH, we are having steady, light winds and a little rain from the storm, but they are predicting average winds of 33 MPH by 2 AM tommorow, so probably much higher gusts. Thankyou for all your blogs, I’m learning so much on particle physics from reading them!

  7. You would think between this and the massive droughts and record high temperatures, global warming would be taken more seriously.

    Do hope nothing too bad happens, with plenty of warning people seem to have been able to prepare well in advance.

  8. Thank you for your explanation and commentary of what is happening there on the East Coast today. Thank goodness for Scientific Technology and the newest forms of tracking down hurricanes. More lives are being saved today and the next few days due to this 21st Century Technology!

  9. Wonderful post! Congrats on being Freshly Pressed!

  10. very clear and informative

  11. Josh-Elearning

    Very well written post

  12. Pingback: Sandy: Amazing. Science: Amazing. | Of Particular Significance

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