Saturday, October 27, 2012

One of My Greatest Fears with Sandy: Storm Surge at NYC...

As I mentioned in yesterday evening's detailed Sandy update, one of my greatest fears as far as impacts go for New York City is that of storm surge.  We will be dealing with a full moon on Monday night, so tide levels will already be above normal.  Combine the astronomical increase in tide levels with salt water being pushed up into the bays and waterways from the Atlantic, and fresh water flowing South in rising rivers due to heavy rainfall being produced by the system, and we have a potential major disaster in the making - just with respect to flooding!

Just like we have computer models that forecast the weather, we also have models at our disposal that aid in forecasting the maximum water height to be expected with a tropical system.  These are called storm surge models.  One such model is produced by the Coastal Emergency Risks Assessment group (CERA).  The images below are from that model, and indicate the expected maximum water heights for the NYC area at landfall on Monday evening.

The first image is a wide view, showing the NYC Metro area and much of Long Island:



The second image is zoomed-in on NYC proper a bit more tightly:


The colorized shadings indicate maximum water levels that progress from 8-10 feet (greenish yellow) to 10-12 feet (brighter yellow - see color scale on each image).

As you can see on the images, with the forecast water heights at these levels, significant portions of lower Manhattan would be under water, as well as many other areas in the Metro.

All of the above is based on the premise that the center of Sandy will make landfall in southern New Jersey, just to the Southwest of Atlantic City.  We wil continue to monitor trends and I will post updated images as the track forecast changes, if it does, but this is the scenario that I have feared would play out for some days now, and I feel that there is a very high likelihood that this will come to pass.

If you live in the greater NYC Metro area, you should generally follow the Hurricane Evacuation Zone guidance that is produced by the city.  You can view the map (which is shown in the thumbnail below) and learn about what Hurricane Evacuation Zone you live in.  I would also consider this the "storm surge evacuation zone" map, and would refer to it either way.  

I said you should "generally" follow the guidance because thus far I am not encouraged by the lackluster performance of local officials in NYC (see yesterday's post for details on that), but hopefully they will wake up today, realize the threat, and issue appropriate recommendations for folks to move out of the most hazardous parts of the city before it is too late.


Right now, based on the storm surge modeling that we discussed above, this is a situation where Zone A and Zone B are in danger.  If you live in those areas (refer to the map at the link in the paragraph above), please don't wait for a government warning.  You need to evaluate your own personal situation and make an informed decision on keeping you, your family and your property safe.

Storm surge is just another of the many reasons that Sandy is a very dangerous storm that should be taken very seriously...

As you might imagine, we are seeing lots of new visitor traffic here on the blog with the approach of Sandy.  Welcome visitors!  Please don't bookmark any particular post for updates, as new posts will be made each time we have new information to pass along.  Please check the homepage of the blog and refresh there for the latest posts...

If you would like to monitor the latest satellite and radar imagery associated with Sandy, please visit the Tropical Page at our sister site, WeatherGuidance.com.  We will be adding additional imagery and information throughout the coming days.

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If you are in need of customized, site specific weather forecasts or storm warnings for your company or event, be sure visit Rob's professional webpage at WeatherGuidance.com.

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