NYC Climate Change

[Nikolai]

While the recent snowiness in the city and surrounding areas can be attributed to various long-term cycles etc, is it possible that the impacts of climate change/global warming are beginning to be felt with more severity in the tri-state?

Since the mid-1990s we have had an unprecedented number of events that have delivered prolific amounts of snowfall to the city... 1/96, 12/00, 2/03, 12/03, 1/05, 2/06, 12/09, two HECS in 2/10, 12/10, and 1/11... we're basically averaging a HECS/12"+ event once per winter at this point.

I don't think any period of time has featured quite so many storms... could the reason be that the offshore waters have become anomalously warm to the point where they can fuel storms that would otherwise be "regular" into becoming these massive events? Even a degree or two of difference in the water temperature could be enough to make a significant impact on the area... the number of major events recently has just been unprecedented, though, and now we've had the most historic October snow event on record, which was another major Nor'Easter...

In the end, even though we are warming somewhat slightly (especially at night), the contrast between the winters that are still cold for the NYC area with the warming ocean could be the reason behind more prolific snow #s in general?

[NYsnowlover]

I would consider that we are entering a new cycle of storminess.

[Sundog]

I would consider that we are entering a new cycle of storminess.

You have to admit increased SST's provide the added energy to get a storm to peak at a higher strength. Doesn't mean that they will take advantage every single time though nor does it mean that other factors that go into creating a very powerful storm will all of sudden be favorable.

[Alpha5]

You have to admit increased SST's provide the added energy to get a storm to peak at a higher strength. Doesn't mean that they will take advantage every single time though nor does it mean that other factors that go into creating a very powerful storm will all of sudden be favorable.

SST didnt power the october storm....it was barely modeled to be below 1000, warmer waters would normally create a stronger low, but that wasnt the case

[uncle W]

NYC saw its worse drought in the 1960's...It ended in September 1966...after a dryish 1970, the year 1971 began a wet period we are still in...this year is going to be the second wettest after the next rain/snow storm...before 1970 the average annual rainfall was around 42"...Since 1971 it's 51"...

[Isotherm]

IMO it's mainly due to the variation in natural teleconnectors.

The 1950s featured wetter than normal winters overall in the OH Valley/Northeast. The warm phase of the AMO was still strong.

Then the 1960s reversed to a negative/cold AMO. The result:

Notice the 2000s were very similar in precip anomaly orientation to the 1950s; not much difference really. +AMO/-PDO signal.

-PDO/+AMO produce dryness from the southern plains into the Southeast, and wet across the north, while -PDO/-AMO (1960s) is as dry as we can get -- both oceans in the cold phase, which removes a significant amount of available energy from the system.

The latter 2000s/2011 featured historic blocking in addition to the warm AMO phase, which fueled the fire in terms of storm generation along the East Coast. Also, global water vapor content decreased over the past 1-2 years, nullifying the idea that global warming produced the major snowstorms of 2010-2011. They were produced largely in combination of the west based blocking and warm AMO/SSTA signal.

[SBUWX23]

SST didnt power the october storm....it was barely modeled to be below 1000, warmer waters would normally create a stronger low, but that wasnt the case

It got down to 977 mb though

[LocoAko]

It is funny that you mention this because I was just discussing this today. While we all know you can't attribute specific events to climate change, I have been hearing more (including at last year's AMS meeting) about how arctic sea ice loss could affect mid-latitude weather. I won't pretend to be an expert on this stuff, but a good primer is located at http://www.arctic.noaa.gov/future/warm_arctic_cold_continent.html . The general premise is that the loss of sea ice makes it much easier for longwave patterns to amplify and for there to be strong cold intrusions into the mid-latitudes despite the overall warming of Earth. Obviously if this continued it'd eventually become statistically less likely for it to snow (while still increasing odds of larger and larger storms?) but as of now these intrusions can actually cause anomalously wintry weather.

Here's one of the links provided on that page.

http://www.arctic.noaa.gov/future/docs/ArcticAND_Globe.pdf (I admittedly haven't read through all of this)

5.2.1 Western Hemisphere

Low-level circulation patterns transport the Arctic air south advecting the surface temperature anomalies into lower latitudes of the North American continent. Jäger and Kellogg (1983) compute average maps of temperature anomalies for ten warmest Arctic winters between 1931 and 1979 and find an overall warming of about 1 K during the warm years extending centrally from Alaska to Florida along with a cooling in the eastern Canadian Arctic. Royer et al. (1990) document a minor warming in the southern and central parts of North America when Arctic sea ice is removed and Murray and Simmonds (1995) find positive 850 hPa height temperature anomalies extending from the Arctic to northern Canada and the western U.S. when Arctic sea ice is reduced. Raymo et al. (1990) report a warming of up to 18 °C over northern Canada and Alaska as well as a minor rise in temperatures in the southern and central parts of North America upon the reduction of sea ice limits in the Arctic during winter. The authors attribute this change to the warming of polar air masses that migrate from the Arctic latitudes southeastward into east central Canada.

...

5.3. Precipitation and storm track activity

Fluctuations in Arctic sea ice exhibit a marked influence on precipitation regimes around the globe, primarily by modifying the behavior of local storm tracks and large-scale planetary wave trains. In the high latitudes where the ice edge is located in close proximity to the local storm track, the atmospheric modifications that arise from the presence of sea ice anomalies in the area also can influence low-level atmospheric baroclinicity and impact the path and intensity of storms (Deser et al., 2000; Alexander et al., 2004). These modified storm systems are subsequently carried by the atmospheric waves away from the initial location of change, thereby having the potential to alter 156 D. Budikova / Global and Planetary Change 68 (2009) 149–163precipitation regimes in various areas throughout the Northern hemisphere. Arctic sea ice decline during winter is generally accompanied by increases in precipitation throughout the middle latitudes of the Northern hemisphere, and as with temperature the large-scale geographic signatures closely resembling those of the negative phase of the NAO. Such conditions typically bring unseasonably wet weather into northern Europe and Alaska, and dry conditions into western U.S. and the Mediterranean region.

I do have to wonder with just how anomalous our storm systems have been lately that this, along with more oceanic latent heat, etc. could be making these storms increasingly statistically likely.