Tag Archives: Blizzard of 2015

What happened to the Blizzard of 2015?

What happened to the Blizzard of 2015? Well, it happened. Despite breathless complaining about how the forecasters got it all wrong, they didn’t. As the storm was predicted, there should have been close to about two feet of snow in the New York City metropolitan area, but as it turns out, there was between 8 and 12 inches. That means that New York City experienced a typical winter month’s worth of snow in one day. Also, most snow that falls on The City falls a few inches at a time and melts more or less instantly, as few cities can match New York in its heat island effect. So, 8-12 inches of snow all at once is a meaningful, crippling snow storm. Two feet would have been much worse, but it is not like The City did not experience a memorable weather event.

More importantly, the forecast was for a huge blizzard with up to three feet of snow across a blob shaped region of the Northeast approximately 475 miles along its longest dimension (see graphic above). The blob ended up being off, on the southwest end, by about 40 or 50 miles. So the spatial extent of the storm was misestimated, days in advance, by about 10%. An object the size of a country was off by the distance a healthy adult can walk in a long day. That was, ladies and gentleman, an excellent, accurate prediction.

nyt-march-29-1976But, since the storm’s outcome was different than predicted in the world’s most inward looking city (you’ve seen the self-effacing maps produced now and then by the New Yorker magazine), it is assumed by many that the forecast was bad, that forecasting was bad, that weather models are bad, and so on.

As meteorologist Paul Douglass told me yesterday when I asked him if he was going to be kneeling on any carpets today over the difference between prediction and reality, “No kneeling, Greg. Just because we tap supercomputers and Doppler radar doesn’t mean we can predict snowfall down to the inch. Models are good and getting better, but they’re not perfect and never will be. People expect perfection in an imperfect world. Boston picked up 20-30” snow, Long Island saw 15-23”, so did much of Connecticut. There was an 8 foot storm surge on Cape Cod where winds gusted to 78 mph.”

Paul also told me something he shared later that day on the Ed Show. “Over 30 years I’ve worked with a series of anchormen in the Twin Cities and Chicago. When they invariably gave me a hard time for busting a forecast I reminded them that a monkey in a sport coat could report on what happened yesterday. Look at the trends and predict tomorrow’s news headlines!” He indicated that when sportscasters started to routinely predict tomorrow’s scores rather than report today’s scores, they would be on a level playing field with the meteorologists.

Here is that Ed Show piece:

The Blizzard of 2015 was in some ways comparable to the Blizzard of 1978, which was one of the first storms of the modern era of increased storminess. The snowfall totals may have been greater for 2015, but coastal winds were greater for 1978. But, in 1978 over 100 people died, and most of them died of exposure because they were caught in the snow. So, in terms of cost of human lives, the two storms are very comparable despite the differences in winds.


Why did over 100 people die in New England’s 1978 storm, but either zero or one person died (depending on attribution of a single sledding accident related death to the storm) in 2015?

Weather forecasting. It got better because the science and technology behind it got better. And, frankly, that is partly a result of storms like the ’78 storm and various hurricanes, which prompted an interest in advancing this technology, which includes on one hand satellites producing piles of data and on the other hand advanced computer and software producing powerful models.

You should buy your local meteorologist a beer.

The image comparing 1978 and 2015 is a chimera of images that come from NOAA and the Boston Globe.

More on the Great Blizzard of 2015

Screen Shot 2015-01-27 at 9.57.51 AMThe Blizzard continues. The center of the low pressure system moved to the northeast more than expected, so the maximum snowfall amounts have also moved deeper into New England, and it the storm may end up dropping the largest amounts Downeast, in Maine, rather than around New York and southern New England. Nonetheless maximum snow totals are heading for 20 inches in many areas west of Boston.

Here, I wanted to alert you to a recent study that talks about “Changes in US East Coast Cyclone Dynamics with Climate Change,” which has this abstract:

Previous studies investigating the impacts of climate change on extratropical cyclones have primarily focused on changes in the frequency, intensity, and distribution of these events. Fewer studies have directly investigated changes in the storm-scale dynamics of individual cyclones. Precipitation associated with these events is projected to increase with warming owing to increased atmospheric water vapor content. This presents the potential for enhancement of cyclone intensity through increased lower-tropospheric diabatic potential vorticity generation. This hypothesis is tested using the Weather Research and Forecasting Model to simulate individual wintertime extratropical cyclone events along the United States East Coast in present-day and future thermodynamic environments. Thermodynamic changes derived from an ensemble of GCMs for the IPCC Fourth Assessment Report (AR4) A2 emissions scenario are applied to analyzed initial and lateral boundary conditions of observed strongly developing cyclone events, holding relative humidity constant. The perturbed boundary conditions are then used to drive future simulations of these strongly developing events. Present-to-future changes in the storm-scale dynamics are assessed using Earth-relative and storm-relative compositing. Precipitation increases at a rate slightly less than that dictated by the Clausius–Clapeyron relation with warming. Increases in cyclone intensity are seen in the form of minimum sea level pressure decreases and a strengthened 10-m wind field. Amplification of the low-level jet occurs because of the enhancement of latent heating. Storm-relative potential vorticity diagnostics indicate a strengthening of diabatic potential vorticity near the cyclone center, thus supporting the hypothesis that enhanced latent heat release is responsible for this regional increase in future cyclone intensity.

In short, today’s storm is the sort of storm we expect to see more often with anthropogenic global warming, and in fact, we have already seen such an increase.

At the Washington Post, Chris Mooney has this: Global Warming Could Make Blizzards Worse, in which he discusses this further (though not in reference to the research noted above). He summarizes, “While I wouldn’t call this a very settled scientific area, there are certainly reasons to think that in a warming world, we might get more snowfall, on average, in certain extreme winter storms.”

Here’s a piece on the Ed Show, with Paul Douglas, putting the storm in context.

The Great Blizzard of 2015: Fair to say it is AGW amplified.

About 20 million people are currently under a blizzard warning, and double that under a winter weather advisory, for a storm moving into the Northeast today and tomorrow, with snow falling though Wednesday. Thousands of flights have been cancelled. Wind will be at tropical storm force, and occasionally, hurricane force, and coastal flooding is expected to be epic. The total amounts of snowfall will be over a foot for a very large area, and well over that here and there, though this is very difficult to predict.

This is a strong low pressure system that will gather significant energy from a warm sea surface as it moves into the Atlantic.

This is a system that would normally not produce a lot of snow, but the odd configuration of the jet stream (once again) is moving the low pressure system through a pattern that will create an epic blizzard.

Storms of roughly this magnitude, in this the New York City area, have occurred in 1888, 1947, 1978, 1993, 1996, 2003, 2006, 2010. A similar pattern would emerge if the focal area was Boston. Weather Wunderground lists these snow events for New York City, indicating that half of the heavy events since the mid nineteenth century have occurred in the last 12 years:

  1. 26.9″ Feb 11-12, 2006
  2. 25.8″ Dec 26-27, 1947
  3. 21.0″ Mar 12-14, 1888
  4. 20.9″ Feb 25-26, 2010
  5. 20.2″ Jan 7-8, 1996
  6. 20.0″ Dec 26-27, 2010
  7. 19.8″ Feb 16-17, 2003
  8. 19.0″ Jan 26-27, 2011
  9. 18.1″ Jan 22-24, 1935
  10. 18.1″ Mar 7-8, 1941

Both the odd jet stream and the warm sea surface temperatures can be pegged as likely effects of anthropogenic global warming (AGW). This added to the clear pattern of more of these storms happening very recently strongly suggest that it is reasonable to characterize this storm as a “global warming amplified storm.” This is not unexpected.

I’m not sure if the sea surface temperatures in the region are at a record high, but they are very high. Over time, North Atlantic sea surface temperatures have certainly risen:

(a) Global annual mean sea-surface temperature (SST) anomalies from HadISST for the period 1870–2008 (Ref. 58)(thin black line). (b) Annual mean North Atlantic SST anomalies for the period 1870–2008 (ref. 58; thin black line). (c) The Atlantic multidecadal oscillation (AMO) index for the period 1870–2008. The modern AMO index4 is defined by subtracting the global mean SST anomalies (a) from the North Atlantic SST anomalies (b). Five-year running means are shown by heavy black lines with fill in all panels.
(a) Global annual mean sea-surface temperature (SST) anomalies from HadISST for the period 1870–2008 (Ref. 58)(thin black line). (b) Annual mean North Atlantic SST anomalies for the period 1870–2008 (ref. 58; thin black line). (c) The Atlantic multidecadal oscillation (AMO) index for the period 1870–2008. The modern AMO index4 is defined by subtracting the global mean SST anomalies (a) from the North Atlantic SST anomalies (b). Five-year running means are shown by heavy black lines with fill in all panels.

And here is the current sea surface temperature anomaly map for the region, showing current temperatures off New York and New England in the upper range:


There has been an increase in extreme precipitation in the Northeast, with a 71% change in the region:


This is inline with predictions the IPCC has been making for some time now. According to climate scientist Michael Mann, “The U.N. Intergovernmental Panel on Climate Change has found that Nor’easters like this one may grow stronger w/ human-caused climate change, as they are driven by the contrast between cold Arctic air masses and ever-warming ocean surface temperatures. We also know that ocean surface temperatures off the U.S. east coast right now are unusually warm, and there is no doubt that a component of that anomalous warmth is due to human-caused climate change. Those warm ocean temperatures also mean that there is more moisture in the air for this storm to feed on and to produce huge snowfalls inland. Climate change is making these sorts of storms more common, much as it is making Sandy-like Superstorms and unusually intense hurricanes more common. Asking whether these storms were caused by climate change, however, is asking the wrong question. What we can say is that they were likely made worse by climate change.”

Kevin Trenbeth, of the National Center for Atmospheric Research notes that the main reason there is a big blizzard coming to the northeast is that it is winter, but “it is warm over the oceans and the contrast between the cold continent and the warm Gulf Stream and surrounding waters is increasing. At present sea surface temperatures are more than 2F above normal over huge expanses (1000 miles) off the east coast and water vapor in the atmosphere is about 10% higher as a result. About half of this can be attributed to climate change.” I would add that the actual anomolies over large areas of the sea where this low pressure system will track are closer to 4 degrees.

There is a live blog at Weather Underground that you may want to keep an eye on, here. There, we see that current predictions for the region are:

New York City, NY: 18 – 24″
Boston, MA: 20 – 30″
Providence, RI: 20 – 30″

The National Weather Service has a page on the storm here.

And, yes, folks, this is a trend: