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A cold wave (known in some regions as a cold snap, cold spell or Arctic Snap) 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 criteria for a cold wave are 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. [1]
In the United States, a cold spell is defined as the national average high temperature dropping below 20 °F (−7 °C). [2] A cold wave of sufficient magnitude and duration may be classified as a cold air outbreak (CAO). [3] [4]
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. [5] Both cold waves and heat waves cause deaths, though different groups of people may be susceptible to different weather events. [6] More temperature-attributable deaths occur during a cold wave than in a heat wave, [7] [8] though the mortality rate is higher in undeveloped regions of the world. 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.
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 a cold wave at higher temperatures than other, colder areas of the globe. The cold wave may be recognized at barely freezing temperatures, as these are still unusually cold for the region, and plant and animal life will be less tolerant of such cold. The same winter temperatures that one associates with the norm for Colorado, Ohio, or Bavaria are catastrophic to 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 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.
Recent research suggests a possible link between cold waves in North America and extratropical cyclogenesis over the East Atlantic. [9] These may be connected by large-scale atmospheric circulation patterns. [10] Examples include Rossby wave propagation from the North Pacific or an upper-level anticyclone west of Greenland. [11] In Europe, the advection of cold air masses from the northeast emerges as a potential precursor signal for the majority of cold waves, significantly affecting the energy, health, and agricultural sectors of the continent. [12]
In some places, such as Siberia, extreme cold requires that fuel-powered machinery intended to be used occasionally must be run continually. 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. [13] 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 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.
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Oymyakon is a rural locality in Oymyakonsky District of the Sakha Republic, Russia, located in the Yana-Oymyakon Highlands, along the Indigirka River, 30 km (19 mi) northwest of Tomtor on the Kolyma Highway. Oymyakon is the coldest permanently inhabited human settlement on Earth, with an average winter temperature of around −50 °C (−58 °F).
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 Rocky Mountains, except Maine.
Delhi features a monsoon influenced humid subtropical climate bordering a hot semi-arid climate, with high variation between summer and winter temperatures and precipitation. Delhi's version of a humid subtropical climate is markedly different from many other humid subtropical cities such as São Paulo, Houston, and Brisbane in that the city features dust storms and wildfire haze due to its semi-arid climate.
North Dakota's climate is typical of a continental climate with cold winters and warm-hot summers. The state's location in the Upper Midwest allows it to experience some of the widest variety of weather in the United States, and each of the four seasons has its own distinct characteristics. The eastern half of the state has a humid continental climate with warm to hot, somewhat humid summers and cold, windy winters, while the western half has a semi-arid climate with less precipitation and less humidity but similar temperature profiles. The areas east of the Missouri River get slightly colder winters, while those west of the stream get higher summer daytime temperatures. In general, the diurnal temperature difference is prone to be more significant in the west due to higher elevation and less humidity.
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.
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, and ended on 3 May 2011 in Poland.
A deadly cold wave started in Europe on January 27, 2012, and brought snow and freezing temperatures to much of the 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 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 and eastern regions of the United States and southern Canada in January 1994. The cold wave caused over 100 deaths in the United States. Two notable cold air events took place from January 18–19 and January 21–22. There were 67 minimum temperature records set on January 19. During this time, much of the United States experienced its coldest temperatures since a major storm on February 20, 1934.
The January–March 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 northeastern 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 2013–14 North American winter was one of the most significant for the United States, due in part to the breakdown of the polar vortex in November 2013, which allowed very cold air to travel down into the United States, leading to an extended period of very cold temperatures. The pattern continued mostly uninterrupted throughout the winter and numerous significant winter storms affected the Eastern United States, with the most notable one being a powerful winter storm that dumped ice and snow in the Southeastern United States and the Northeastern United States in mid-February. Most of the cold weather abated by the end of March, though a few winter storms did affect the Western United States towards the end of the winter.
The November 2014 North American cold wave was an extreme weather event that occurred across most of Canada and the contiguous United States, including parts of the Western United States up to western California. One of the first events of the winter, the cold wave was caused by the northward movement of an extremely powerful bomb cyclone associated with Typhoon Nuri's remnant, which shifted the jet stream far northward, creating an omega block pattern. This allowed a piece of the polar vortex to advance southward into the Central and Eastern United States, bringing record-cold temperatures to much of the region. In contrast, Alaska experienced above-average temperatures.
The 2014–15 North American winter was frigid and prolifically wintry, especially across the eastern half of North America in the months of January–March. The season began early, with many places in North America experiencing 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. In addition, significant winter weather occurred throughout the season, including a major blizzard that struck the Northeastern United States at the end of January, another blizzard that affected much of the Northern United States days later in early February, and several significant snow events paired with very frigid temperatures for much of February.
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 73 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 southward 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 Spring 2013 United Kingdom cold wave was a period of unusually cold weather in the United Kingdom between 6 March and early April 2013. The cold wave 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 Wales. Most parts of England, north Wales and the Isle of Man also suffered heavy persistent snowfall on 22 and 23 March 2013.
The 2018–19 North American winter was unusually cold within the Northern United States, with frigid temperatures being recorded within the middle of the season. Several notable events occurred, such as a rare snow in the Southeast in December, a strong cold wave and several major winter storms in the Midwest, and upper Northeast and much of Canada in late January and early February, record snowstorms in the Southwest in late February, deadly tornado outbreaks in the Southeast and a historic mid-April blizzard in the Midwest, but the most notable event of the winter was a record-breaking bomb cyclone that affected much of the Central United States and Canada in mid-March. Unlike previous winters, a developing weak El Niño was expected to influence weather patterns across North America. Overall, however, winter of 2018–19 had many La Niña like conditions, being mild along the mid- and lower parts of the East Coast, the West Coast, and most of the southern Plains. Overall, the meteorological winter of 2018-19 became the wettest on record for the United States.
In late January 2019, a severe cold wave caused by a weakened jet stream around the Arctic polar vortex hit the Midwestern United States and Eastern Canada, killing at least 22 people. It came after a winter storm brought up to 13 inches (33 cm) of snow in some regions from January 27–29, and brought the coldest temperatures in over 20 years to most locations in the affected region, including some all-time record lows. In early February, a concentration of Arctic air colloquially referred to as the "polar vortex" moved west, and became locked over Western Canada and the Western United States. As a result, February 2019 was among the coldest and snowiest on record in these regions. In early March, the cold once again shifted east, breaking records in many areas. In mid-March, the cold wave finally retreated, but combined with above-average temperatures, precipitation, and a deep snowpack, widespread flooding ensued in the Central US.
The 2019–20 North American winter was unusually warm for many parts of the United States; in many areas, neutral ENSO conditions controlled the weather patterns, resulting in strong El Niño like conditions and the sixth-warmest winter on record, and many areas in the Northeastern United States saw one of the least snowy winters in years. In fact, Baltimore and Islip saw no snow in February for the first time. Some notable events still occurred, such as a powerful blizzard that impacted the Western United States in late November, a series of cold shots in January and February, a snowstorm within the Texas Panhandle and a late-season blizzard in the High Plains.
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