White Christmas (weather)
A white Christmas refers to the presence of snow on Christmas Day. This phenomenon is most common in the northern countries of the Northern Hemisphere. Because December is in the middle of the Southern Hemisphere summer, white Christmases there are extremely rare, except in Antarctica, in the Southern Alps of New Zealand's South Island, and in parts of the Andes in South America. The Irving Berlin song, "White Christmas", sung by Bing Crosby and based on the film of the same name, is the highest-selling single of all time and speaks nostalgically of a traditional, snow-covered Christmas.
Definition
The definition of "White Christmas" varies. In most countries, it simply means that the ground is covered by snow or hail at Christmas, but some countries have more strict definitions. In the United States, the official definition of a white Christmas is that there has to be a snow depth of at least 1 inch (2.5 cm) at 7:00 a.m. local time on Christmas morning,[1] and in Canada the official definition is that there has to be more than 2 cm (0.79 in) on the ground on Christmas Day.[2] In the United Kingdom, although for many a white Christmas simply means a complete covering of snow or hail on Christmas Day, the official definition by the British Met Office and British bookmakers is for snow to be observed falling, however little, (even if it melts before it reaches the ground) in the 24 hours of 25 December.[3][4] Consequently, according to the Met Office and British bookmakers, even 3 ft (91 cm) of snow on the ground at Christmas, because of a heavy snow fall a few days before, will not constitute a white Christmas, but a few snow flakes mixed with rain will, even if they never reach the ground. In the United Kingdom the most likely place to see snowfall on a Christmas Day is in North and North Eastern Scotland, in Aberdeen, Aberdeenshire or the Highlands.[5]
White Christmases in Canada
In most parts of Canada it is likely to have a white Christmas in most years, except for the coast and southern interior valleys of British Columbia, southern Alberta, southern Ontario, and parts of Atlantic Canada - in those places Christmas without snow is not uncommon in warmer years, with the British Columbia coast the least likely place to have a white Christmas.
The Meteorological Service of Canada compiled a list of the probability of a white Christmas in selected Canadian cities for 2007:
| Location | Probability |
|---|---|
| Vancouver | 11% |
| Calgary | 59% |
| Edmonton | 88% |
| Saskatoon | 98% |
| Regina | 91% |
| Winnipeg | 98% |
| Sudbury | 100% |
| Windsor | 50% |
| Toronto | 37% |
| Ottawa | 83% |
| Montreal | 80% |
| Quebec City | 99% |
| Halifax | 59% |
| St. John's | 65% |
| Whitehorse | 100% |
| Yellowknife | 100% |
2006 saw some of the warmest weather on record, with such places as Quebec City experiencing their first green Christmas in recorded history.[6]
In 2008, Canada experienced the first nationwide white Christmas in 37 years, as a series of pre-Christmas storms hit the nation, including the normally rainy BC Pacific coast.
White Christmases in the United States
In the United States, there is often snow on the ground at Christmas in the northern states, except in the Pacific Northwest. Some of the least likely white Christmases that have happened include the 2004 Christmas Eve Snowstorm, which brought the first white Christmas in 50 years to New Orleans and caused the first recorded white Christmas in Houston, Texas. The 2004 storm also brought the first measurable snow of any kind since 1895 to Brownsville, Texas, and its twin city of Matamoros, Mexico. The Florida winter storm of 1989 also occurred immediately before Christmas causing a white Christmas for cities like Pensacola and Jacksonville. The same storm buried Wilmington, North Carolina and the rest of Southeastern North Carolina under 15 in (38 cm) of snow.
In the United States the notion of a white Christmas is often associated in the American popular consciousness with a Christmas celebration that includes traditional observances in the company of friends and family. White Christmas is an Irving Berlin song reminiscing about an old-fashioned Christmas setting.
According to the National Climatic Data Center, basing numbers upon 1988-2005 data and stations with at least 25 years of data, the probability of a white Christmas (1 in (2.5 cm) of snow on the ground) at selected cities is as follows:[7]
According to research by CDIAC meteorologist Dale Kaiser, the United States during the second half of the 20th century experienced declining frequencies of white Christmases, especially in the northeastern region.[8]
White Christmases in the United Kingdom and Ireland
In the United Kingdom, white Christmases were more common from the 1550s to the 1850s, during the Little Ice Age, but during the 20th Century there were only seven official white Christmases in England.
In Ireland, the prospect of early winter snow is always remote due to the country's mild and wet climate. Bookmakers offer odds every year for a white Christmas, which is officially snow being recorded at 09:00 local time on Christmas Day, and recorded at either Dublin Airport, Belfast International Airport or Cork Airport (bets are offered for each airport). Snow is most common in the north, and, as such, Belfast usually has better odds than Dublin, and considerably better odds than Cork, which is at the extreme south of the country. Christmas Day 2010 was Ireland's most recent White Christmas which saw most parts of Ireland covered in lying snow from heavy falls throughout the previous week.[9]
Although most places in the UK has some chance of seeing snow in the winter, it very rarely falls at Christmas (generally in January and February). However it does occur, with an average of seeing a White Christmas every 6 years. From 1950 to 2006, the percentage of years with a white Christmas in the UK was as follows:[10]
| Location | Probability |
|---|---|
| London | 6% |
| Birmingham | 15% |
| Aberporth | 9% |
| Glasgow | 35% |
| Aberdeen | 53% |
| Belfast | 22% |
| Lerwick | 75% |
| Bradford | 14% (since 1971) |
| St Mawgan | 10% (since 1957) |
Christmas 2009 was a white Christmas in some parts of Britain, with thick lying snow which easterly winds had brought over the previous week. Travel over much of Britain was badly affected by ice and snow on roads, and was made more slippery by partial daytime thaw followed by overnight refreezing. It was the first white Christmas anywhere in the United Kingdom since 2004.
Christmas 2010 brought the most significant White Christmas to Ireland in many years. While little or no falling snow was recorded on this date, heavy snow falls throughout the previous week in most parts of Ireland ensured nearly every county enjoyed a complete covering of many centimetres of snow. Met Eireann reported in its December Weather Summary that Casement Aerodrome weather station in Dublin had 27 cm (11 in) of snow lying on the ground on Christmas morning. Christmas 2009 reported lying snow in many places in Ireland and prior to that, Christmas 2004 also recorded snow at most Irish weather stations.
White Christmases in Romania
| Location | Probability |
|---|---|
| Bucharest | 75% |
| Iași | 80% |
| Timişoara | 70% |
| Cluj Napoca | 85% |
| Constanta | 65% |
| Miercurea Ciuc | 90% |
| Craiova | 75% |
| Braşov | 85% |
| Satu Mare | 75% |
White Christmases in other parts of Europe
In Europe, snow at Christmas is common in Norway, Sweden, Finland, the Baltic States, Russia, Ukraine, Belarus, and Poland. In general, due to the influence of the warm Gulf Stream on European climate, chances of a white Christmas are lower the further west. For example, in southern France a white Christmas is very rare, while in Bucharest, Romania, which is at a similar latitude, it is much more likely. Northern Italy and the mountain regions of central-south Italy may also have a white Christmas. In cities such as Turin, Milan or Bologna a Christmas with falling snow or snow on the ground is not a rarity.
Southern Hemisphere
Because Christmas occurs during the summer, white Christmases are especially rare events in the Southern hemisphere, apart from Antarctica which is generally uninhabited. In 2006, a snowstorm hit the Snowy Mountains in New South Wales and Victoria, arriving on Christmas Morning and bringing nearly 12 in (30 cm) of snow in higher areas.[11] This was an especially rare event because it occurred during Australia's typically warm summer. However a significant accumulation of hail, which can fall in the summer, occurred on the ground in some areas of Melbourne on Christmas Day 2011, giving the appearance of a 'White Christmas'. [12] In New Zealand's Southern Alps snow can fall any day of the year and a white Christmas is very possible. A white Christmas in the southern hemisphere (specifically those close to Antarctica) is approximately equivalent to having snow in the northern hemisphere on June 25, and in some ways is even less likely because the Northern Hemisphere has population centers farther from the equator than does the Southern Hemisphere.
References
- ^ National Oceanic and Atmospheric Administration: White Christmas?. Retrieved 2010-12-25
- ^ CBC News: "Chances vary for a white Christmas". Retrieved 2010-12-25
- ^ "Are you dreaming of a white Christmas?". Met Office. 2008-11-19. Retrieved 2009-12-13.
- ^ William Hill press release: "£1 Million Riding On A Flake Of Snow!". Retrieved 2010-12-25
- ^ Meteorology West Moors: Snow at Christmas in the United Kingdom. Retrieved 2010-12-25
- ^ (CBC) (CTV) Ontario Weather Review - December 2006 Environment Canada
- ^ Will We Have a White Christmas?, National Climatic Data Center, 20 August 2008.
- ^ Dye, Lee. Study: White Christmases Have Become Rare. ABC News. December 18, 2003.
- ^ "Chances of white Christmas begin to drift | IOL". Breakingnews.iol.ie. 2006-12-17. Retrieved 2009-12-13.
- ^ "National Meteorological Library" (PDF). Retrieved 2009-12-13.
- ^ "Aussies celebrate white Christmas. 25 December 2006. ABC News Online". Abc.net.au. 2006-12-25. Retrieved 2010-05-24.
- ^ http://www.heraldsun.com.au/news/pictures/gallery-e6frf94x-1226230231439
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