61-646: Cyclone Herwart was a European windstorm that affected Southern Denmark , Germany , Poland , Austria , Hungary and the Czech Republic on 28–29 October 2017. Named by the Free University of Berlin Meteorology Department, the storm was an extratropical cyclone formed as a secondary low to a more northerly centre of low pressure named Grischa coming southward from the Svalbard Islands region,
122-467: A phone in poll on 17 July 1991 and claimed that 72% of the 40,000 responses favored keeping the names. This made the DWD pause and think about the naming system and these days the DWD accept the naming system and request that it is maintained. During 1998 a debate started about whether it was discriminatory to name areas of high pressure with male names and the areas of low pressure with female names. The issue
183-444: A strong signal between NAO and grasshopper species composition in the tall grass prairies of the midwestern United States. They found that, even though NAO does not significantly affect the weather in the midwest, there was a significant increase in abundance of common grasshopper species (i.e. Hypochlora alba, Hesperotettix spp., Phoetaliotes nebrascensis, M. scudderi, M. keeleri, and Pseudopomala brachyptera ) following winters during
244-770: Is a weather phenomenon over the North Atlantic Ocean of fluctuations in the difference of atmospheric pressure at sea level (SLP) between the Icelandic Low and the Azores High . Through fluctuations in the strength of the Icelandic Low and the Azores High, it controls the strength and direction of westerly winds and location of storm tracks across the North Atlantic. The NAO was discovered through several studies in
305-634: Is aligned with the NAO state during the cyclones' development phase. The strongest storms are embedded within, and form in large scale atmospheric flow. It should be kept in mind that, on the other hand, the cyclones themselves play a major role in steering the NAO phase. Aggregate European windstorm losses show a strong dependence on NAO, with losses increasing/decreasing 10-15% at all return periods. A connection between wintertime cold air outbreaks in North America and European windstorms has been hypothesized in
366-642: Is connected to the rare Arctic dipole anomaly . In the north western part of the Atlantic, both of these winters were mild, especially 2009–2010, which was the warmest recorded in Canada. The winter of 2010-2011 was particularly above normal in the northern Arctic regions of that country. The probability of cold winters with much snow in Central Europe rises when the Arctic is covered by less sea ice in summer. Scientists of
427-514: Is frequent. If westerlies are suppressed, the temperature is more extreme in summer and winter leading to heat waves , deep freezes and reduced rainfall. A permanent low-pressure system over Iceland (the Icelandic Low ) and a permanent high-pressure system over the Azores (the Azores High ) control the direction and strength of westerly winds into Europe. The relative strengths and positions of these systems vary from year to year and this variation
488-404: Is important to both the interpretation of historic sea level records and predictions of future sea level trends, as mean pressure fluctuations of the order of millibars can lead to sea level fluctuations of the order of centimeters. By controlling the position of the Azores High, the NAO also influences the direction of general storm paths for major North Atlantic tropical cyclones : a position of
549-581: Is known as the NAO. A large difference in the pressure at the two stations (a high index year, denoted NAO+) leads to increased westerlies and, consequently, cool summers and mild and wet winters in Central Europe and its Atlantic facade. In contrast, if the index is low (NAO-), westerlies are suppressed, northern European areas suffer cold dry winters and storms track southwards toward the Mediterranean Sea . This brings increased storm activity and rainfall to southern Europe and North Africa. Especially during
610-498: Is not in reference to the structurally different tropical cyclone of the same name, but to the hurricane strength of the wind on the Beaufort scale (winds ≥ 118 km/h or ≥ 73 mph). In English, use of term hurricane to refer to European windstorms is mostly discouraged, as these storms do not display the structure of tropical storms. Likewise the use of the French term ouragan
671-665: Is on 29 October. The storm and rainfall caused death and destruction. Train connections were closed in Northern Germany, and major bridges in Denmark were closed for traffic. Herwart caused disruption to the German energy market as the strong winds caused an over-supply of energy onto the German power grid. Prices for energy slipped into negative values as low as minus €83.06 per megawatt hour, with an average low of minus €52.11 (normal energy prices are €37 per megawatt hour). These values were
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#1733085223000732-807: Is similarly discouraged as hurricane is in English, as it is typically reserved for tropical storms only. European windstorms in Latin Europe are generally referred to by derivatives of tempestas ( tempest , tempête , tempestado , tempesta ), meaning storm, weather, or season, from the Latin tempus , meaning time. Globally storms of this type forming between 30° and 60° latitude are known as extratropical cyclones . The name European windstorm reflects that these storms in Europe are primarily notable for their strong winds and associated damage, which can span several nations on
793-587: Is used by the meteorology department to maintain weather observations at the Free University. Names are listed alphabetically beginning in January. Several European languages use cognates of the word huracán ( ouragan , uragano , orkan , huragan , orkaan , ураган , which may or may not be differentiated from tropical hurricanes in these languages) to indicate particularly strong cyclonic winds occurring in Europe. The term hurricane as applied to these storms
854-521: The Atlantic multidecadal oscillation (AMO). The NAO has multiple possible definitions. The easiest to understand are those based on measuring the seasonal average air pressure difference between stations, such as: These definitions all have in common the same northern point (because this is the only station in the region with a long record) in Iceland ; and various southern points. All are attempting to capture
915-737: The Fukushima Daiichi nuclear disaster , but the event at Hunterston was rated as International Nuclear Event Scale 2. A year later in 1999 during the Lothar storm Flooding at the Blayais Nuclear Power Plant resulted in a "level 2" event on the International Nuclear Event Scale. Cyclone Lothar and Martin in 1999 left 3.4 million customers in France without electricity, and forced Électricité de France to acquire all
976-649: The North Sea reduces survival of cod larvae which are at the upper limits of their temperature tolerance, as does the cooling in the Labrador Sea, where the cod larvae are at their lower temperature limits. Though not the critical factor, the NAO+ peak in the early 1990s may have contributed to the collapse of the Newfoundland cod fishery . In southwestern Europe, NAO- events are associated with increased aeolian activity. On
1037-668: The Tibetan Plateau , where increases in aridity resulting in significant forest mortality and intensification of dust storms have been linked to NAO- events. The winter of 2009–10 in Europe was unusually cold. It is hypothesized that this may be due to a combination of low solar activity, a warm phase of the El Niño–Southern Oscillation and a strong easterly phase of the Quasi-Biennial Oscillation all occurring simultaneously. The Met Office reported that
1098-592: The Azores High farther to the south tends to force storms into the Gulf of Mexico , whereas a northern position allows them to track up the North American Atlantic Coast. As paleotempestological research has shown, few major hurricanes struck the Gulf coast during 3000–1400 BC and again during the most recent millennium. These quiescent intervals were separated by a hyperactive period during 1400 BC – 1000 AD, when
1159-571: The East Coast of the United States an NAO+ causes warmer temperatures and increased rainfall, and thus warmer, less saline surface water. This prevents nutrient-rich upwelling which has reduced productivity. Georges Bank and the Gulf of Maine are affected by this reduced cod catch. The strength of the NAO is also a determinant in the population fluctuations of the intensively studied Soay sheep . Strangely enough, Jonas and Joern (2007) found
1220-571: The German media started to commonly use the names, however, they were not officially approved by the German Meteorological Service Deutscher Wetterdienst . The DWD subsequently banned the usage of the names by their offices during July 1991, after complaints had poured in about the naming system. However, the order was leaked to the German press agency, Deutsche Presse-Agentur , who ran it as its lead weather story. Germany's ZDF television channel subsequently ran
1281-477: The Gulf coast was struck frequently by catastrophic hurricanes and their landfall probabilities increased by 3–5 times. Until recently, the NAO had been in an overall more positive regime since the late 1970s, bringing colder conditions to the North-West Atlantic, which has been linked with the thriving populations of Labrador Sea snow crabs , which have a low temperature optimum. The NAO+ warming of
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#17330852230001342-434: The NAO. There is some debate as to how much the NAO impacts short term weather over North America. While most agree that the impact of the NAO is much less over the United States than for Western Europe, the NAO is also believed to affect the weather over much of upper central and eastern areas of North America. During the winter, when the index is high (NAO+), the Azores High draws a stronger south-westerly circulation over
1403-632: The Potsdam Research Unit of the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association have decrypted a mechanism in which a shrinking summertime sea ice cover changes the air pressure zones in the Arctic atmosphere and effects on European winter weather. If there is a particularly large-scale melt of Arctic sea ice in summer, as observed in recent years, two important effects are intensified. Firstly,
1464-660: The UK and France was interrupted, and the storm caused a domino-effect of power outages throughout the Southeast of England. Conversely windstorms can produce too much wind power. Cyclone Xynthia hit Europe in 2010, generating 19000 megawatts of electricity from Germany's 21000 wind turbines. The electricity produced was too much for consumers to use, and prices on the European Energy Exchange in Leipzig plummeted, which resulted in
1525-511: The UK, for example, had experienced its coldest winter for 30 years. This coincided with an exceptionally negative phase of the NAO. Analysis published in mid-2010 confirmed that the concurrent ' El Niño ' event and the rare occurrence of an extremely negative NAO were involved. However, during the winter of 2010–11 in Northern and Western Europe , the Icelandic Low , typically positioned west of Iceland and east of Greenland, appeared regularly to
1586-600: The United Kingdom's needs via the Langeled pipeline . However, the disruption came at a time of low demand. The same storm also saw the Leningrad Nuclear Power Plant also affected, as algae and mud stirred up by the storm were sucked into the cooling system, resulting in one of the generators being shut down. A similar situation was reported in the wake of Storm Angus in 2016 (though not linked specifically to
1647-482: The United States can incur winter cold outbreaks more than the norm with associated heavy snowstorms. In summer, a strong NAO- is thought to contribute to a weakened jet stream that normally pulls zonal systems into the Atlantic Basin contributing significantly to excessively long-lasting heat waves over Europe, however, recent studies do not show the evidence of these associations. More recent studies have shown that
1708-535: The available portable power generators in Europe, with some even being brought in from Canada. These storms brought a fourth of France's high-tension transmission lines down and 300 high-voltage transmission pylons were toppled. It was one of the greatest energy disruptions ever experienced by a modern developed country. Following the Great Storm of 1987 the High Voltage Cross-Channel Link between
1769-455: The components (pressure centers strength, and locations) of the NAO are more powerful to investigate the relationships to seasonal and sub-seasonal climate variability over Europe, North America and the Mediterranean region. Under a positive NAO index (NAO+), regional reduction in atmospheric pressure results in a regional rise in sea level due to the 'inverse barometer effect'. This effect
1830-457: The continent. The strongest cyclones are called windstorms within academia and the insurance industry. The name European windstorm has not been adopted by the UK Met Office in broadcasts (though it is used in their academic research ), the media or by the general public, and appears to have gained currency in academic and insurance circles as a linguistic and terminologically neutral name for
1891-506: The date, or the Saint's day of their occurrence. Although standardised naming schemes now exist, a storm may still be named differently in different countries. For instance, the Norwegian weather service also names independently notable storms that affect Norway , which can result in multiple names being used in different countries they affect, such as: In 2011, a social media campaign resulted in
Cyclone Herwart - Misplaced Pages Continue
1952-415: The east of Iceland and so allowed exceptionally cold air into Europe from the Arctic. A strong area of high pressure was initially situated over Greenland , reversing the normal wind pattern in the northwestern Atlantic, creating a blocking pattern driving warm air into northeastern Canada and cold air into Western Europe, as was the case during the previous winter. This occurred during a La Niña season, and
2013-533: The eastern half of the North American continent which prevents Arctic air from plunging southward (into the United States south of 40 latitude). In combination with the El Niño , this effect can produce significantly warmer winters over the upper Midwest and New England , but the impact to the south of these areas is debatable. Conversely, when the NAO index is low (NAO-), the upper central and northeastern portions of
2074-474: The grid operators having to pay over 18 euros per megawatt-hour to offload it, costing around half a million euros in total. Disruption of the gas supply during Cyclone Dagmar in 2011 left Royal Dutch Shell 's Ormen Lange gas processing plant in Norway inoperable after its electricity was cut off by the storm. This left gas supplies in the United Kingdom vulnerable as this facility can supply up to 20 per cent of
2135-511: The highest amount of natural catastrophe insurance loss in Europe. The state of the North Atlantic Oscillation relates strongly to the frequency, intensity, and tracks of European windstorms. An enhanced number of storms have been noted over the North Atlantic region during positive NAO phases (compared to negative NAO phases) and is due to larger areas of suitable growth conditions. The occurrence of extreme North Atlantic cyclones
2196-658: The last years. Cold spells over Central Canada and Eastern US appear to be associated with more frequent windstorms and flash floods over Iberia, whereas cold spells over Eastern Canada show a connection to windstorms over Northern Europe and the British Isles. The reason behind those teleconnections is not fully clear yet, but changes in the behavior of the Polar jet stream are likely to be at least related to this effect. Temporal clustering of windstorm events has also been noted, with eight consecutive storms hitting Europe during
2257-605: The late 19th and early 20th centuries. Unlike the El Niño–Southern Oscillation phenomenon in the Pacific Ocean, the NAO is a largely atmospheric mode. It is one of the most important manifestations of climate fluctuations in the North Atlantic and surrounding humid climates. The North Atlantic Oscillation is closely related to the Arctic oscillation (AO) (or Northern Annular Mode (NAM)), but should not be confused with
2318-427: The latter splitting in two low-pressure areas late on 28 October. The center of Herwart started rotating counterclockwise around the main low pressure area, passing over Norway , Sweden , Latvia and then losing power while moving over western Russia . In Denmark, which was hit on 28 October, the storm was named Ingolf . In Hungary, the storm was named Nárcisz ( Narcissus ), a Hungarian female name whose name day
2379-526: The losses of the 2007 United Kingdom floods . On average, some 200,000 buildings are damaged by high winds in the UK every year. European windstorms wipe out electrical generation capacity across large areas, making supplementation from abroad difficult (windturbines shut down to avoid damage and nuclear capacity may shut if cooling water is contaminated or flooding of the power plant occurs). Transmission capabilities can also be severely limited if power lines are brought down by snow, ice or high winds. In
2440-500: The lowest since Christmas 2012. This can lead to a situation where Austria and Switzerland find it attractive to use the energy in their pumped storage reservoirs, where it can later be sold back to Germany. Herwart was not as strong as Xavier which struck Germany earlier in October 2017. Herwart is considered one of the strongest storms of the past 10 years in Germany, ranked in 8th place in
2501-403: The months of November to April, the NAO is responsible for much of the variability of weather in the North Atlantic region, affecting wind speed and wind direction changes, changes in temperature and moisture distribution and the intensity, number and track of storms. Research now suggests that the NAO may be more predictable than previously assumed and skillful winter forecasts may be possible for
Cyclone Herwart - Misplaced Pages Continue
2562-494: The name European cyclones , with North-Atlantic cyclone and North-Atlantic windstorms also being used. Though with the advent of the "Name our Storms" project, they are generally known as storms. Insurance losses from European windstorms are the second greatest source of loss for any natural peril globally. Only Atlantic hurricanes in the United States are larger. Windstorm losses exceed those caused by flooding in Europe. For instance one windstorm, Kyrill in 2007, exceeded
2623-428: The negative phase when pressure differences are low, cold Arctic air can then easily penetrate southward through Europe without being interrupted by the usual westerlies. Model calculations show that the air pressure difference with decreased sea ice cover in the Arctic summer is weakened in the following winter, enabling Arctic cold to push down to mid-latitudes. Despite one of the strongest El Niño events recorded in
2684-533: The ocean is warmer than the atmosphere. The warming of the air near to the ground leads to rising movements and the atmosphere becomes less stable. One of these patterns is the air pressure difference between the Arctic and mid-latitudes: the Arctic oscillation with the Azores highs and Iceland lows known from the weather reports. If this difference is high, a strong westerly wind will result which in winter carries warm and humid Atlantic air masses right down to Europe. In
2745-703: The phenomena. In contrast to some other European languages there is a lack of a widely accepted name for these storms in English. The Met Office and UK media generally refer to these storms as severe gales . The current definition of severe gales (which warrants the issue of a weather warning) are repeated gusts of 70 mph (110 km/h) or more over inland areas. European windstorms are also described in forecasts variously as winter storms , winter lows , autumnal lows , Atlantic lows and cyclonic systems . They are also sometimes referred to as bullseye isobars and dartboard lows in reference to their appearance on weather charts. A Royal Society exhibition has used
2806-419: The positive phase of NAO and a significant increase in the abundance of less common species (i.e. Campylacantha olivacea, Melanoplus sanguinipes, Mermiria picta, Melanoplus packardii, and Boopedon gracile ) following winters during a negative phase of the NAO. This is thought to be the first study showing a link between NAO and terrestrial insects in North America. The NAO's ecological effects extend as far as
2867-450: The retreat of the light ice surface reveals the darker ocean, causing it to warm up more in summer from the solar radiation ( ice–albedo feedback mechanism). Secondly, the diminished ice cover can no longer prevent the heat stored in the ocean being released into the atmosphere ( lid effect ). As a result of the decreased sea ice cover the air is warmed more greatly than it used to be particularly in autumn and winter because during this period
2928-426: The same pattern of variation, by choosing stations in the "eye" of the two stable pressure areas, the Azores High and the Icelandic Low (shown in the graphic). A more complex definition, only possible with more complete modern records generated by numerical weather prediction , is based on the principal empirical orthogonal function (EOF) of surface pressure. This definition has a high degree of correlation with
2989-404: The sea. When the grid connection was restored, the generators that had powered the station during the blackout were shut down and left on "manual start", so when the power failed again the station was powered by batteries for a short time of around 30 minutes, until the diesel generators were started manually. During this period the reactors were left without forced cooling, in a similar fashion to
3050-509: The station-based definition. This then leads onto a debate as to whether the NAO is distinct from the AO/NAM, and if not, which of the two is to be considered the most physically based expression of atmospheric structure (as opposed to the one that most clearly falls out of mathematical expression). Westerly winds blowing across the Atlantic bring moist air into Europe. In years when westerlies are strong, summers are cool, winters are mild and rain
3111-404: The storm officially called Cyclone Friedhelm being widely referred to as Hurricane Bawbag and Hurricane Fannybaws. Such usage of the term Hurricane is not without precedent, as the 1968 Scotland storm was referred to as "Hurricane Low Q". The UK Met Office and Ireland's Met Éireann held discussions about developing a common naming system for Atlantic storms. In 2015 a pilot project by
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#17330852230003172-629: The storm) when reactor 1 at Torness Nuclear Power Station in Scotland was taken offline after a sea water intake tripped due to excess seaweed around the inlet. Also following Storm Angus the UK's National Grid launched an investigation into whether a ship's anchor damaged four of the eight cables of the Cross Channel high voltage interconnector , which would leave it only able to operate at half of its capacity until February 2017. North Atlantic Oscillation The North Atlantic Oscillation ( NAO )
3233-659: The strongest storms there in the last decade, but not considered memorable when compared to the strongest storms such as Kyrill (2007) and Lothar (1999). Herwart was responsible for the worst insurance losses in the Czech Republic since the storms Kyrill and Emma (2008). This article about or related to natural disasters is a stub . You can help Misplaced Pages by expanding it . European windstorm European windstorms are powerful extratropical cyclones which form as cyclonic windstorms associated with areas of low atmospheric pressure . They can occur throughout
3294-449: The surface, can be placed into three categories, namely the "warm jet", the "cold jet" and the "sting jet". These phenomena vary in terms of physical mechanisms, atmospheric structure, spatial extent, duration, severity level, predictability and location relative to cyclone and fronts. On average, these storms cause economic damage of around €1.9 billion per year and insurance losses of €1.4 billion per year (1990–1998). They cause
3355-564: The track is further south, it may cause adverse weather conditions across Central Europe , Northern Europe and especially Western Europe . The countries most commonly affected include the United Kingdom , Ireland , the Netherlands , Norway , Germany , the Faroe Islands and Iceland . The strong wind phenomena intrinsic to European windstorms, that give rise to "damage footprints" at
3416-490: The two forecasters was launched as " Name our storms " which sought public participation in naming large-scale cyclonic windstorms affecting the UK and/or Ireland over the winter of 2015/16. The UK/Ireland storm naming system began its first operational season in 2015/2016, with Storm Abigail. During 1954, Karla Wege, a student at the Free University of Berlin's meteorological institute suggested that names should be assigned to all areas of low and high pressure that influenced
3477-566: The wake of Cyclone Gudrun in 2005 Denmark and Latvia had difficulty importing electricity, and Sweden lost 25% of its total power capacity as the Ringhals Nuclear Power Plant and Barsebäck nuclear power plant nuclear plants were shut down. During the Boxing Day Storm of 1998 the reactors at Hunterston B nuclear power station were shut down when power was lost, possibly due to arcing at pylons caused by salt spray from
3538-426: The weather of Central Europe. The university subsequently started to name every area of high or low pressure within its weather forecasts, from a list of 260 male and 260 female names submitted by its students. The female names were assigned to areas of low pressure while male names were assigned to areas of high pressure. The names were subsequently exclusively used by Berlin's media until February 1990, after which
3599-401: The winter of 1989/90. Cyclones Lothar and Martin in 1999 were separated by only 36 hours. Cyclone Kyrill in 2007 followed only four days after Cyclone Per . In November 2011, Cyclone Berit moved across Northern Europe, and just a day later another storm, named Yoda, hit the same area. Up to the second half of the 19th century, European windstorms were usually named either by the year,
3660-523: The year, but are most frequent between October and March, with peak intensity in the winter months. Deep areas of low pressure are common over the North Atlantic, and occasionally start as nor'easters off the New England coast. They frequently track across the North Atlantic Ocean towards the north of Scotland and into the Norwegian Sea , which generally minimizes the impact to inland areas; however, if
3721-422: Was subsequently resolved by alternating male and female names each year. In November 2002 the "Adopt-a-Vortex" scheme began, which allows members of the public or companies to buy naming rights for a letter chosen by the buyer that are then assigned alphabetically to high and low pressure areas in Europe during each year. The naming comes with the slim chance that the system will be notable. The money raised by this
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