|The surface winds on 30 October 2012 illustrated by http://hint.fm/wind/ show how the superstorm dominated the weather after landfall.|
This blizzard was the reincarnation of the week-long storm that hit California last week, yet another powerful loop in a world-wide series of disturbances. The recent storms across Europe and Russia are more unusually strong loops in the jet stream. Climatologically, these are due to a variation in the location of the quasi-static high- and low-pressure systems around the northern hemisphere. For instance, there is a high pressure system over the mid-Atlantic (normally, the Bermuda high) accompanied by a low pressure system over Iceland. This year, this "North Atlantic Oscillation" pair weakened and moved eastward. Last summer, that allowed the hurricanes to move northward across the mid-Atlantic instead of the west-Atlantic, sparing the US East Coast. This winter, that pattern allows polar outbreaks to move freely across the eastern USA, freezing the East Coast in December. On the other side of the Atlantic, Europe gets unusual amounts of polar air and snow. For more discussion of the NAO, visit NOAA's Climate Prediction Center).
East Coast blizzards occur in concert with the world-wide ENSO variations, roughly every decade. I can personally recall similar blizzards paralyzing the Washington DC area in 1978, 1983, 1993-4, and 2009-10. Great blizzards paralyzing New York City and Boston are legendary. The expert on the subject works at NOAA: Paul Kocin (firstname.lastname@example.org, 301-763-8201). He has written government monographs on the subject. He sees a pattern where a loop in the jet stream around a polar high over the Appalachians is redirected back to the northwest by an air mass over Newfoundland, carrying moisture mixed with cold wind back over the upper East Coast, instead of out-to-sea.
I found a book on my shelf titled "Great Blizzards of New York City" by Kevin Ambrose (1994), with photos of great blizzards in 1888, 1899, 1920, 1935, 1947, 1961, 1969, 1978, 1983, 1993 and 1994.
Our animation consists of clouds scanned 3 to 4 times per hour by NOAA's GOES weather satellite overlaid on a true-color map from NASA's TERRA climate satellite. During the day, the cold (colored white) cloud tops observed by the GOES infrared channels are texture-enhanced using the reflected sunlight in visible channel on GOES. Making it look natural involves several thousand lines of computer coding.
Once the overlay was working, we automated it and assemble movies from the recent frames. We offer the color overlays and movies for the previous week on the web (goes.gsfc.nasa.gov). It's an unattended 24/7 service. We are gratified to see our color pictures used by the press to illustrate the hourly progress of storms, though the pictures are usually credited to "AP" instead of "NOAA-NASA".
The GOES views of snow storms are most useful for observing lake-effect snows and offshore intensity. Because snow forms at low altitude and is rather transparent to weather radar, the GOES cloud observations provide data that the weather radar doesn't see.
There are physical limits to snow storm predictability. In the last 30 years, chaos theory has demonstrated that weather and climate is inherently unpredictable to some limit because of natural instabilities in the atmosphere. That limit has been slowly pushed out by better observations and computer models. For instance, the 1978 East Coast blizzard, which developed much like the recent one, was unpredicted. All the 2010 blizzards have had good 3- to 5-day forecasts, with well-advertized uncertainty in the storm track. It's not clear how much past 5 days we can ever make a reliable weather forecast for a naturally unstable situation.
Storms are moved across the country by the jet stream, up around 35,000 ft. Low pressure systems form as unstable loops in the jet stream. Consequently, weather forecasters pay more attention to the upper air wind, which is the cause, than the surface pressure, which is the effect. Broadcast meteorologists concentrate on the surface conditions, because that is where their customers live and work.