Snow, Snow, Everywhere
Is it growing warmer or it growing colder? In the US and in Europe it is hard to tell this year. As of now about 71% of the USA is covered with a layer of snow. Comparing earlier January amounts this is the highest in the last 7 years. 2010 was 56% with a low of 21% in 2006. Average snow depth has also increased proportionately in this time frame. The winters of 1976-77 and 1977-78 were the two of the coldest USA winters in recent times so we have a way to go yet. The winter of 2009—2010 in Europe was also unusually cold. Globally there were atypical snowfalls in several parts of the Northern Hemisphere. In January 2010, the northern half of Europe experienced its coldest winters since 1981—1982. The winter of 2010-2011 in Europe began with an unusually cold November caused by a cold weather cycle that started in southern Scandinavia and subsequently moved south and west over both Belgium and the Netherlands on 25 November and into the west of Scotland and North East England on 26 November. This was due to a low pressure zone in the Baltics, with a high pressure over Greenland on 24 November.
The Farmers’ Almanac predicted this year that Old Man Winter will exhibit a split personality. The eastern third of the country, (New England down to Florida and as far west as the lower Ohio River and Mississippi River Valley), will experience colder-than-normal winter temperatures. Yet the Almanac concluded that overall this winter would be kinder and gentler. Only time will tell.
The principal source affecting the 2010-11 winter overall weather pattern is the phenomenon called La Nina, when sea surface temperatures across the equatorial central and eastern Pacific are below normal. La Nina strengthens as the departure increases.
La Nina winters are typically synonymous with harsh conditions across the northern tier of the United States and drier-than-normal conditions throughout the southern tier.
In Europe this season, a cold front moved out of Siberia on November 24, and cold spell and snow storms also hit the Alps, on the 26th before hitting the UK on November 29. Other earlier, but unrelated, storms had dusted Northumberland and Scottish Borders Region on November 23, before being absorbed in to the advancing Scandinavian weather system.
Heavy snow caused many problems across the UK and the first disruption of Snowfall occurred on November 24 in the Grampians, Eastern Scotland and Cairngorms, where snow showers blown from a northerly wind caused havoc as accumulations up to 8 in in Aviemore made conditions difficult and major roads in Aberdeen had gridlock problems in the rush hour. Further snow disrupted all of Scotland, Southern Wales, Northern Ireland, South West and England and much of the North and East of England as snow accumulated to over 24 inches in rural settlements.
So Europe and the US are having rough winters this year. This may just a statistical fluke but there is a lot of snow out there this year.
For further information: http://www.nohrsc.noaa.gov/nsa/index.html?region=National&year=2007&month=1&day=12&units=e