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The Great Blizzard of 2015: Fair to say it is AGW enhanced. [Greg Laden's Blog]
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
9. 18.1″ Mar 7-8, 1941
Both the odd jet stream and the warm sea surface temperatures can be pegged as likely effects of global warming. 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 enhanced storm.”
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.
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 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.
Source: http://scienceblogs.com/gregladen/2015/01/26/the-great-blizzard-of-2015-fair-to-say-it-is-agw-enhanced/
