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A cold wave (known in some regions as a cold snap or cold spell) is a weather phenomenon that is distinguished by a cooling of the air. Specifically, as used by the U.S. National Weather Service, a cold wave is a rapid fall in temperature within a 24-hour period requiring substantially increased protection to agriculture, industry, commerce, and social activities. The precise criterion for a cold wave is determined by the rate at which the temperature falls, and the minimum to which it falls. This minimum temperature is dependent on the geographical region and time of year.
In the United States, a cold spell is defined as the national average high temperature dropping below 20 °F (−7 °C). A cold wave of sufficient magnitude and duration may be classified as a cold air outbreak (CAO).
A cold wave can cause death and injury to livestock and wildlife. Exposure to cold mandates greater caloric intake for all animals, including humans, and if a cold wave is accompanied by heavy and persistent snow, grazing animals may be unable to reach needed food and die of hypothermia or starvation. They often necessitate the purchase of foodstuffs to feed livestock at considerable cost to farmers.
Cold spells are associated with increased mortality rates in populations around the world.Both cold waves and heat waves cause deaths, though different groups of people may be susceptible to different weather events. In developed countries, more deaths occur during a heat wave than in a cold snap, though the mortality rate is higher in undeveloped regions of the world. Globally, more people die during hot weather than cold weather. Extreme winter cold often causes poorly insulated water pipelines and mains to freeze. Even some poorly protected indoor plumbing ruptures as water expands within them, causing much damage to property and costly insurance claims. Demand for electrical power and fuels rises dramatically during such times, even though the generation of electrical power may fail due to the freezing of water necessary for the generation of hydroelectricity. Some metals may become brittle at low temperatures. Motor vehicles may fail when antifreeze fails or motor oil gels, producing a failure of the transportation system. To be sure, such is more likely in places like Siberia and much of Canada that customarily get very cold weather.
Fires become even more of a hazard during extreme cold. Water mains may break and water supplies may become unreliable, making firefighting more difficult. The air during a cold wave is typically denser and thus contains more oxygen, so when air that a fire draws in becomes unusually cold it is likely to cause a more intense fire[ citation needed ]. However, snow may stop spreading of fires, especially wildfires.
Winter cold waves that are not considered cold in some areas, but cause temperatures significantly below average for an area, are also destructive. Areas with subtropical climates may recognize unusual cold, perhaps barely freezing, temperatures, as a cold wave. In such places, plant and animal life is less tolerant of such cold as may appear rarely. The same winter temperatures that one associates with the norm for Colorado, Ohio, or Bavaria are catastrophic to winter crops in places like Florida, California, or parts of South America that grow fruit and vegetables in winter.
Cold waves that bring unexpected freezes and frosts during the growing season in mid-latitude zones can kill plants during the early and most vulnerable stages of growth, resulting in crop failure as plants are killed before they can be harvested economically. Such cold waves have caused famines. At times as deadly to plants as drought, cold waves can leave a land in danger of later brush and forest fires that consume dead biomass. One extreme was the so-called Year Without a Summer of 1816, one of several years during the 1810s in which numerous crops failed during freakish summer cold snaps after volcanic eruptions that reduced incoming sunlight.
In some places, such as Siberia, extreme cold requires that fuel-powered machinery to be used even part-time must be run continuously. Internal plumbing can be wrapped, and persons can often run water continuously through pipes. Energy conservation, difficult as it is in a cold wave, may require such measures as collecting people (especially the poor and elderly) in communal shelters. Even the homeless may be arrested and taken to shelters, only to be released when the hazard abates.Hospitals can prepare for the admission of victims of frostbite and hypothermia; schools and other public buildings can be converted into shelters.
People can stock up on food, water, and other necessities before a cold wave. Some may even choose to migrate to places of milder climates, at least during the winter. Suitable stocks of forage can be secured before cold waves for livestock, and livestock in vulnerable areas might be shipped from affected areas or even slaughtered. Smudge pots can bring smoke that prevents hard freezes on a farm or grove. Vulnerable crops may be sprayed with water that will paradoxically protect the plants by freezing and absorbing the cold from surrounding air.
Most people can dress appropriately and can even layer their clothing should they need to go outside or should their heating fail. They can also stock candles, matches, flashlights, and portable fuel for cooking and wood for fireplaces or wood stoves, as necessary. However caution should be taken as the use of charcoal fires for cooking or heating within an enclosed dwelling is extremely dangerous due to carbon monoxide poisoning. Adults must remain aware of the exposure that children and the elderly have to cold.
The first snowfall began on 17 December 2009, before a respite over the Christmas period. −17.6 °C (0.3 °F) in Greater Manchester, England. The snow spread to Southern England on 6 January and by 7 January the United Kingdom was blanketed in snow, which was captured by NASA's Terra satellite. The thaw came a week later, as temperatures started to increase. The winter weather brought widespread transport disruption, school closures, power failures, the postponement of sporting events and 25 deaths. A low of −22.3 °C (−8.1 °F) was recorded in Altnaharra, Scotland on 8 January 2010. Overall it was the coldest winter since 1978–79, with a mean temperature of 1.5 °C (34.7 °F).The most severe snowy weather began on 5 January in North West England and west Scotland with temperatures hitting a low of
1904 was the coolest year on record.
The United Kingdom straddles the higher mid-latitudes between 49° and 61° N on the western seaboard of Europe. Since the UK is always in or close to the path of the polar front jet stream, frequent changes in pressure and unsettled weather are typical. Many types of weather can be experienced in a single day. In general the climate of the UK is cool and often cloudy and rainy, and high temperatures are infrequent.
Oymyakon is a rural locality in Oymyakonsky District of the Sakha Republic, Russia, located along the Indigirka River, 30 kilometers (19 mi) northwest of Tomtor on the Kolyma Highway. It is one of the coldest permanently inhabited settlements on Earth.
Milwaukee has a humid continental climate, with four distinct seasons and wide variations in temperature and precipitation in short periods of time. The city's climate is also strongly influenced by nearby Lake Michigan, which creates two varying climates within the Milwaukee area. The Urban heat island effect also plays a role in the city's climate, insulating it from winter cold, but keeping it cooler in spring and summer.
The cold wave of 1978 was a weather event that occurred in the eastern United States. Beginning in December 1977 and lasting until March, it produced one of the coldest winters on record in all states east of the Rockies except Maine.
The 1936 North American cold wave ranks among the most intense cold waves in the recorded history of North America. The Midwestern United States and the Canadian Prairies were hit the hardest. Only the Southwestern United States and California largely escaped its effects.
The winter of 1894–95 was severe for the British Isles with a CET of 1.27 °C or 34.3 °F. Many climatologists have come to view this winter as the end of the Little Ice Age and the culmination of a decade of harsh winters in Britain. Whereas the average CET for the ten winters from 1885–86 to 1894–95 was 2.87 °C or 37.2 °F, no winter with a CET under 3.0 °C or 37.4 °F followed for twenty-two years and no month as cold as February or January 1895 until 1940. In contrast, between 1659 and 1894 no spell with every winter CET above 3.0 °C or 37.4 °F had lasted longer than twelve winters.
The January 1987 snowfall was a very heavy lake-effect type snow event that affected the United Kingdom, mainly the areas of East Anglia, South-East England and London between 11 and 14 January and was the heaviest snowfall to fall in that part of the United Kingdom since the winter of 1981/82. Over 50 centimetres (20 in) of snow fell in South East England, with some locations reporting snowfall at 75 centimetres (30 in). Ireland was also affected by the cold wave, reporting more than 10 centimetres (3.9 in) in some areas.
Quetta, Pakistan features a continental arid climate with a large variation between summer and winter temperatures. The highest temperature recorded in Quetta was 42 °C (108 °F) on 10 July 1998. The lowest temperature in Quetta is −18.3 °C (−0.9 °F) which was recorded on 8 January 1970.
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 early 2012 European cold wave was a deadly cold wave that started on January 27, 2012, and brought snow and freezing temperatures to much of the European continent. There were more than 824 reported deaths in both Europe and North Africa. Particularly low temperatures hit several Eastern and Northern European countries, reaching as low as −42.7 °C (−44.9 °F) in Finland. The heaviest snow was recorded in the Balkan region. The cold weather was a result of an extensive area of very high pressure located over the north east of the continent in northern Russia, which circulated cold air from the east.
The cold wave of January 1977 produced the only known trace of snow in the greater Miami area of Florida ever reported, although the city itself did not report any snow. It occurred following the passage of a strong cold front, in combination with a high-pressure area situated over the Mississippi River Valley. As a result, cold air moved far to the south across Florida, causing both snow flurries and record low temperatures. Most notably, the weather system brought snow flurries as far south as Homestead on January 19. No snow had ever been reported in southeastern Florida before or since. Damage was most significant to agriculture, as major losses occurred to Citrus fruits and tender vegetables. Statewide, agricultural damage from the cold wave totaled to $350 million (1977 USD), and losses overall totaled to $2 billion (1977 USD). One fatality occurred due to an automobile accident in Central Florida, which was related to the cold wave.
The 2013 extreme weather events included several all-time temperature records in Northern and Southern Hemisphere. The February extent of snow cover in Eurasia and North America was above average, while the extent of Arctic ice in the same month was 4.5% below the 1981–2010 average. The Northern Hemisphere weather extremes have been linked to the melting of Arctic sea ice, which alters atmospheric circulation in a way that leads to more snow and ice.
The 1994 North American cold wave occurred over the midwestern United States, eastern United States, and southern Canada during January 1994. Two notable cold air events occurred from January 18–19 and from January 21–22. There were 67 minimum temperature records set on January 19. Indiana and Kentucky both set state records on January 19. The United States experienced its coldest temperature month since February 1934, although much of the West experienced mild temperatures. Washington and Idaho experienced the second-warmest January recorded in the previous 100 years.
The 2014 North American cold wave was an extreme weather event that extended through the late winter months of the 2013–2014 winter season, and was also part of an unusually cold winter affecting parts of Canada and parts of the north-central and upper eastern United States. The event occurred in early 2014 and was caused by a southward shift of the North Polar Vortex. Record-low temperatures also extended well into March.
The 2014–15 North American winter refers to winter in North America as it occurred across the continent from late 2014 through early 2015. While both the meteorological and astronomical definitions of winter involve the onset of winter occurring in December, many places in North America experienced their first wintry weather during mid November. A period of below-average temperatures affected much of the contiguous United States, and several records were broken. An early trace of snowfall was recorded in Arkansas. There were greater accumulations of snow across parts of Oklahoma as well. A quasi-permanent phenomenon referred to as the polar vortex may have been partly responsible for the cold weather. Temperatures in much of the United States dropped 15 to 35 °F below average by November 19 following a southward "dip" of the polar vortex into the eastern two-thirds of the country. The effects of this dip were widespread, bringing about temperatures as low as 28 °F (−2 °C) in Pensacola, Florida. Following a significant snowstorm there, Buffalo, New York received several feet of snow from November 17–21. During the 2014–15 winter season, Boston broke its all-time official seasonal 107.6-inch (2.73-meter) snowfall record from the winter of 1995–96, with a total snowfall record of 108.6 inches (2.76 m) as of March 15, 2015.
Sweden had a very unusual start and finish to the year 2010, with two consecutive winter cold waves occurring in a single calendar year. Since both events were notable, both are covered in this article.
A period of exceptionally cold and snowy winter weather in January 2017 occurred in Eastern and Central Europe. In some areas, flights and shipping services were suspended, and there was major disruption to power supplies and other essential infrastructure. The weather was the result of stationary high pressure over western Europe, resulting in strong winds circulating from Russia and Scandinavia towards eastern Europe. On 9 January, the Continental Arctic (cA) air mass extended from Germany across the Balkans, resulting in deep snow in Greece and strong bora winds affecting Croatia in particular. In addition, heavy snow in central and Southern Italy was the result of cold air flowing across the warmer Adriatic Sea. At least 61 deaths were attributed to the cold wave.
The February 2015 North American cold wave was an extreme weather event that affected most of Canada and the eastern half of the United States. Following an earlier cold wave in the winter, the period of below-average temperatures contributed to an already unusually cold winter for the Eastern U.S. Several places broke their records for their coldest February on record, while some areas came very close. The cause of the cold wave was due to the polar vortex advancing southwards into the eastern parts of the U.S, and even making it as far south as the Southeast, where large snow falls are rare. By the beginning of March, although the pattern did continue for the first week, it abated and retreated near the official end of the winter.
The 2017–18 North American winter refers to winter in North America as it occurred across the continent from late 2017 through early 2018. Similar to the previous winter, a La Niña was expected to influence the winter weather across North America. Winter weather patterns were very active, erratic, and protracted, especially near the end of the season. Significant events included rare snowfall in the South, a strong cold wave that affected the United States during the early weeks of January, and a series of strong nor'easters that affected the Northeastern U.S during the month of March. In addition, flooding also took place during the month of February in the Central United States. Finally the winter came to a conclusion with a powerful storm system that caused a tornado outbreak and flooding in mid-April. The most intense event, however, was an extremely powerful cyclonic blizzard that impacted the northeastern United States in the first week of 2018.
The Spring 2013 United Kingdom cold spell was a period of unusually cold weather in the United Kingdom between 6 March and early April 2013. The cold spell consisted of very low temperatures and significant snowfall. Freezing temperatures worsened due to the significant overcast and cloud covered skies. Extensive snowfall occurred on 11 and 12 March in the South East, North and West of England and in Wales. England as a whole also suffered heavy snowfall on 22 and 23 March 2013.
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