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75-618: A vast amount of data was collected from several other platforms to conduct research into precipitation mechanisms, severe storm development, hail suppression, hydrology and microwave propagation. Numerous researchers have used the dataset and during the period 1990 to 1994, 23 publications appeared in journals and conferences, as well as 4 scientific reports were prepared. These papers have included radar meteorology , cloud physics , hydrology/hydro meteorology , computer science , instrumentation, synoptic weather, dynamic and mesoscale meteorology . The project area covered 33,700 km and

150-430: A cumulonimbus cloud (thundercloud) or a cumulus cloud , in rare cases. Tornadoes come in many sizes but typically form a visible condensation funnel whose narrowest end reaches the earth and surrounded by a cloud of debris and dust . Tornadoes' wind speeds generally average between 40 miles per hour (64 km/h) and 110 miles per hour (180 km/h). They are approximately 250 feet (76 m) across and travel

225-607: A low-pressure area whose center of rotation is just off the coast and whose leading winds in the left-forward quadrant rotate onto land from the northeast. High storm waves may sink ships at sea and cause coastal flooding and beach erosion . Notable nor'easters include The Great Blizzard of 1888 , one of the worst blizzards in U.S. history. It dropped 100–130 cm (40–50 in) of snow and had sustained winds of more than 45 miles per hour (72 km/h) that produced snowdrifts in excess of 50 feet (15 m). Railroads were shut down and people were confined to their houses for up to

300-436: A mesonetwork . The radar would be used to detect not only the intensity of the precipitation by its reflectivity , but the type of hydrometeors with the circular polarization . These would be correlated with the surface observations to study the structure of the thunderstorms leading to hail formation. Furthermore, at certain times there would be aircraft flight in and around convective areas to gather further information on

375-760: A severe thunderstorm warning from the United States National Weather Service (excludes flash floods), the Environment Canada , the Australian Bureau of Meteorology , the Meteorological Service of New Zealand and the Meteorological Office UK, if the event occurs in those countries. If a tornado is occurring (a tornado has been seen by spotters ) or is imminent ( Doppler weather radar has observed strong rotation in

450-535: A tornado , winds in a downburst are not rotational but are directed outwards from the point where they strike land or water. "Dry downbursts" are associated with thunderstorms with very little precipitation, while wet downbursts are generated by thunderstorms with large amounts of rainfall. Microbursts are very small downbursts with winds that extend up to 2.5 miles (4 km) from their source, while macrobursts are large-scale downbursts with winds that extend in excess of 2.5 miles (4 km). The heat burst

525-476: A blizzard as a severe snow storm characterized by strong winds causing blowing snow that results in low visibilities. The difference between a blizzard and a snowstorm is the strength of the wind, not the amount of snow. To be a blizzard, a snow storm must have sustained winds or frequent gusts that are greater than or equal to 56 km/h (35 mph) with blowing or drifting snow which reduces visibility to 400 m or 0.25 mi or less and must last for

600-692: A cold front and warm front mix together and a blizzard forms at the border line. Another storm system occurs when a cold core low over the Hudson Bay area in Canada is displaced southward over southeastern Canada, the Great Lakes, and New England . When the rapidly moving cold front collides with warmer air coming north from the Gulf of Mexico , strong surface winds, significant cold air advection , and extensive wintry precipitation occur. Low pressure systems moving out of

675-517: A dusting of snow and areas such as Birmingham, Alabama , received up to 12 in (30 cm) with hurricane-force wind gusts and record low barometric pressures . Between Louisiana and Cuba, hurricane-force winds produced high storm surges across northwestern Florida, which along with scattered tornadoes killed dozens of people. In the United States, the storm was responsible for the loss of electric power to over 10 million customers. It

750-485: A few miles (kilometers) before dissipating. Some attain wind speeds in excess of 300 miles per hour (480 km/h), may stretch more than two miles (3.2 km) across, and maintain contact with the ground for dozens of miles (more than 100 km). The Enhanced Fujita Scale and the TORRO Scale are two examples of scales used to rate the strength, intensity and/or damage of a tornado. Tornadoes, despite being one of

825-633: A low of −30 °C (−22 °F), with up to 180 centimetres (71 in) of snow in the more mountainous regions, killing at least 926 people. It was the third deadliest blizzard in history. The weather also claimed more than 100,000 sheep and goats, and nearly 315,000 cattle died. The winter of 1880–1881 is widely considered the most severe winter ever known in many parts of the United States. The initial blizzard in October 1880 brought snowfalls so deep that two-story homes experienced accumulations , as opposed to drifts, up to their second-floor windows. No one

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900-507: A mesoscale low-pressure area forms behind the rain shield (a high pressure system under the rain canopy) of a mature squall line and is sometimes associated with a heat burst . Squall lines often cause severe straight-line wind damage, and most non-tornadic wind damage is caused from squall lines. Although the primary danger from squall lines is straight-line winds, some squall lines also contain weak tornadoes. Very high winds can be caused by mature tropical cyclones (called hurricanes in

975-543: A number of hazards, most of which are floods or hazards resulting from floods. Flooding is the inundation of areas that are not normally under water. It is typically divided into three classes: River flooding, which relates to rivers rising outside their normal banks; flash flooding, which is the process where a landscape, often in urban and arid environments, is subjected to rapid floods; and coastal flooding, which can be caused by strong winds from tropical or non-tropical cyclones. Meteorologically , excessive rains occur within

1050-455: A plume of air with high amounts of moisture (also known as an atmospheric river ), which is directed around an upper level cold-core low or a tropical cyclone. Flash flooding can frequently occur in slow-moving thunderstorms and are usually caused by the heavy liquid precipitation that accompanies it. Flash floods are most common in densely populated urban environments, where less plants and bodies of water are presented to absorb and contain

1125-426: A prolonged period of time—typically three hours or more. Environment Canada defines a blizzard as a storm with wind speeds exceeding 40 km/h (25 mph) accompanied by visibility of 400 metres (0.25 mi) or less, resulting from snowfall, blowing snow, or a combination of the two. These conditions must persist for a period of at least four hours for the storm to be classified as a blizzard, except north of

1200-443: A snow-water equivalent (SWE) ratio of between 6:1 and 12:1 and a weight in excess of 10 pounds per square foot (~50 kg/m ) piles onto trees or electricity lines, significant damage may occur on a scale usually associated with strong tropical cyclones. An avalanche can occur with a sudden thermal or mechanical impact on snow that has accumulated on a mountain, which causes the snow to rush downhill suddenly. Preceding an avalanche

1275-414: A storm , indicating an incipient tornado), the severe thunderstorm warning will be superseded by a tornado warning in the United States and Canada. A severe weather outbreak is typically considered to be when ten or more tornadoes, some of which will likely be long-tracked and violent, and many large hail or damaging wind reports occur within one or more consecutive days. Severity is also dependent on

1350-419: A stretch of line a new storm arrived, burying it again. There were no winter thaws and on February 2, 1881, a second massive blizzard struck that lasted for nine days. In towns the streets were filled with solid drifts to the tops of the buildings and tunneling was necessary to move about. Homes and barns were completely covered, compelling farmers to construct fragile tunnels in order to feed their stock. When

1425-424: A time, particularly where snowfall is unusual or rare. A severe blizzard has winds over 72 km/h (45 mph), near zero visibility, and temperatures of −12 °C (10 °F) or lower. In Antarctica , blizzards are associated with winds spilling over the edge of the ice plateau at an average velocity of 160 km/h (99 mph). Ground blizzard refers to a weather condition where loose snow or ice on

1500-456: A true whiteout, there is no visible horizon. People can become lost in their own front yards, when the door is only 3 m (10 ft) away, and they would have to feel their way back. Motorists have to stop their cars where they are, as the road is impossible to see. A nor'easter is a macro-scale storm that occurs off the New England and Atlantic Canada coastlines. It gets its name from

1575-526: A week. It killed 400 people, mostly in New York . The 1972 Iran blizzard , which caused 4,000 reported deaths, was the deadliest blizzard in recorded history. Dropping as much as 26 feet (7.9 m) of snow, it completely covered 200 villages. After a snowfall lasting nearly a week, an area the size of Wisconsin was entirely buried in snow. The 2008 Afghanistan blizzard , was a fierce blizzard that struck Afghanistan on 10 January 2008. Temperatures fell to

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1650-408: A wildfire are especially vulnerable to ignition from firebrands. Spotting can create spot fires as hot embers and firebrands ignite fuels downwind from the fire. In Australian bushfires, spot fires are known to occur as far as 10 kilometers (6 mi) from the fire front. Since the mid-1980s, earlier snowmelt and associated warming has also been associated with an increase in length and severity of

1725-504: A year's worth of rainfall from a tropical cyclone passage. Tropical cyclones can also relieve drought conditions. They also carry heat and energy away from the tropics and transport it toward temperate latitudes , which makes them an important part of the global atmospheric circulation mechanism. As a result, tropical cyclones help to maintain equilibrium in the Earth's troposphere . When extratropical cyclones deposit heavy, wet snow with

1800-653: Is a stub . You can help Misplaced Pages by expanding it . Severe weather Severe weather is any dangerous meteorological phenomenon with the potential to cause damage, serious social disruption, or loss of human life. These vary depending on the latitude , altitude , topography , and atmospheric conditions. High winds , hail , excessive precipitation , and wildfires are forms and effects, as are thunderstorms , downbursts , tornadoes , waterspouts , tropical cyclones , and extratropical cyclones . Regional and seasonal phenomena include blizzards ( snowstorms ), ice storms , and duststorms . Severe weather

1875-614: Is a major cause of wildfires in China and in the Mediterranean Basin . In Australia, the source of wildfires can be traced to both lightning strikes and human activities such as machinery sparks and cast-away cigarette butts." Wildfires have a rapid forward rate of spread (FROS) when burning through dense, uninterrupted fuels. They can move as fast as 10.8 kilometers per hour (6.7 mph) in forests and 22 kilometers per hour (14 mph) in grasslands. Wildfires can advance tangential to

1950-577: Is a phenomenon known as an avalanche wind caused by the approaching avalanche itself, which adds to its destructive potential. Large amounts of snow that accumulate on top of man-made structures can lead to structural failure. During snowmelt, acidic precipitation that previously fell in the snow pack is released and harms marine life. Lake-effect snow is produced in the winter in the shape of one or more elongated bands. This occurs when cold winds move across long expanses of warmer lake water, providing energy and picking up water vapor , which then freezes and

2025-488: Is a severe snowstorm characterized by strong sustained winds and low visibility, lasting for a prolonged period of time—typically at least three or four hours. A ground blizzard is a weather condition where snow that has already fallen is being blown by wind. Blizzards can have an immense size and usually stretch to hundreds or thousands of kilometres. In the United States, the National Weather Service defines

2100-602: Is called a Nor'easter . They are so named because their winds come from the northeast , especially in the coastal areas of the Northeastern United States and Atlantic Canada. More specifically, it describes a low-pressure area whose center of rotation is just off the upper East Coast and whose leading winds in the left forward quadrant rotate onto land from the northeast. Nor'easters may cause coastal flooding , coastal erosion , heavy rain or snow, and hurricane-force winds. The precipitation pattern of Nor'easters

2175-614: Is created by vertical currents on the backside of old outflow boundaries and squall lines where rainfall is lacking. Heat bursts generate significantly higher temperatures due to the lack of rain-cooled air in their formation. Derechos are longer, usually stronger, forms of downburst winds characterized by straight-lined windstorms. Downbursts create vertical wind shear or microbursts , which are dangerous to aviation. These convective downbursts can produce damaging winds, lasting 5 to 30 minutes, with wind speeds as high as 168 mph (75 m/s), and cause tornado-like damage on

2250-643: Is deposited on the lee shores . For more information on this effect see the main article. Conditions within blizzards often include large quantities of blowing snow and strong winds that may significantly reduce visibility. Reduced viability of personnel on foot may result in extended exposure to the blizzard and increase the chance of becoming lost. The strong winds associated with blizzards create wind chill that can result in frostbites and hypothermia . The strong winds present in blizzards are capable of damaging plants and may cause power outages, frozen pipes, and cut off fuel lines. Blizzard A blizzard

2325-449: Is done to larger buildings. Total destruction to man-made structures occurs when winds reach 175 knots (324 km/h). The Saffir–Simpson scale for cyclones and Enhanced Fujita scale ( TORRO scale in Europe) for tornadoes were developed to help estimate wind speed from the damage they cause. A dangerous rotating column of air in contact with both the surface of the earth and the base of

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2400-406: Is one type of extreme weather , which includes unexpected, unusual, severe, or unseasonal weather and is by definition rare for that location or time of the year. Due to the effects of climate change , the frequency and intensity of some of the extreme weather events are increasing, for example, heatwaves and droughts . Meteorologists have generally defined severe weather as any aspect of

2475-450: Is similar to other mature extratropical storms . Nor'easters can cause heavy rain or snow, either within their comma-head precipitation pattern or along their trailing cold or stationary front. Nor'easters can occur at any time of the year but are mostly known for their presence in the winter season. A dust storm is an unusual form of windstorm that is characterized by the existence of large quantities of sand and dust particles carried by

2550-458: Is used to develop models to predict the most frequent and possible locations. This information is used to notify affected areas and save lives. Severe thunderstorms can be assessed in three different categories. These are "approaching severe", "severe", and "significantly severe". Approaching severe is defined as hail between 1 ⁄ 2 to 1 inch (13 to 25 mm) diameter or winds between 50 and 58 mph (50 knots, 80–93 km/h). In

2625-445: The arctic tree line , where that threshold is raised to six hours. The Australia Bureau of Meteorology describes a blizzard as, "Violent and very cold wind which is laden with snow, some part, at least, of which has been raised from snow covered ground." While severe cold and large amounts of drifting snow may accompany blizzards, they are not required. Blizzards can bring whiteout conditions, and can paralyze regions for days at

2700-501: The common cold . Possible trench foot infections may also occur when personnel are exposed for extended periods of time within flooded areas. A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain or squalls. A tropical cyclone feeds on heat released when moist air rises, resulting in condensation of water vapor contained in

2775-585: The North Atlantic Ocean on March 15. It is unique for its intensity, massive size and wide-reaching effect. At its height, the storm stretched from Canada towards Central America, but its main impact was on the United States and Cuba. The cyclone moved through the Gulf of Mexico, and then through the Eastern United States before moving into Canada. Areas as far south as northern Alabama and Georgia received

2850-470: The North Atlantic. These windstorms are commonly associated with the destructive extratropical cyclones and their low pressure frontal systems. European windstorms occur mainly in the seasons of autumn and winter. Severe European windstorms are often characterized by heavy precipitation as well. A synoptic-scale extratropical storm along the upper East Coast of the United States and Atlantic Canada

2925-524: The Rocky Mountains onto the Great Plains, a broad expanse of flat land, much of it covered in prairie , steppe and grassland , can cause thunderstorms and rain to the south and heavy snows and strong winds to the north. With few trees or other obstructions to reduce wind and blowing, this part of the country is particularly vulnerable to blizzards with very low temperatures and whiteout conditions. In

3000-498: The United States and Canada and typhoons in eastern Asia). A tropical cyclone's heavy surf created by such winds may cause harm to marine life either close to or upon the surface of the water, such as coral reefs . Coastal regions usually take more serious wind damage than inland, due to rapid dissipation upon landfall, though heavy rain from their remnants may flood either. Severe local windstorms in Europe that develop from winds off

3075-466: The United States, such storms will usually warrant a Significant Weather Alert . Severe is defined as hail 1 to 2 inches (25 to 51 mm) diameter, winds 58 to 75 miles per hour (93 to 121 km/h), or a tornado. Significant severe is defined as hail 2 inches (51 mm) in diameter or larger, winds 75 mph (65 knots, 120 km/h) or more, or a tornado of strength EF2 or stronger. Both severe and significant severe events warrant

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3150-399: The atmospheric conditions and sample the clouds. Observations were also made by sampling vehicles . The vehicles were outfitted with various meteorological instrumentation and hail catching apparatus. They were directed into suspected thunderstorm hail regions by a controller at the radar site. The controller communicated with the vehicles by radio. This article about atmospheric science

3225-416: The atmospheric conditions on hail days within 3 h (i.e., between 1415 and 2015 LT) and 100 km from the sounding site. A few of these proximity soundings had to be excluded because of missing data or because they were modified by precipitation or a thunderstorm outflow boundary . In addition to upper-air sounding data, the surface temperature and dewpoint (representative of the storm's inflow) were obtained from

3300-549: The cause of costly and deadly events throughout history. One of the earliest recorded incidents occurred around the 12th century in Wellesbourne , Britain. The largest hailstone in terms of maximum circumference and length ever recorded in the United States fell in 2003 in Aurora, Nebraska , USA. The hailstone had a diameter of 7 inches (18 cm) and a circumference of 18.75 inches (47.6 cm). Heavy rainfall can lead to

3375-534: The children's book The Long Winter by Laura Ingalls Wilder , in which the author tells of her family's efforts to survive. The snow arrived in October 1880 and blizzard followed blizzard throughout the winter and into March 1881, leaving many areas snowbound throughout the winter. Accurate details in Wilder's novel include the blizzards' frequency and the deep cold, the Chicago and North Western Railway stopping trains until

3450-517: The density of the cloud and fall towards the ground. The downdrafts in cumulonimbus clouds can also cause increases in the speed of the falling hailstones. The term hailstorm is usually used to describe the existence of significant quantities or size of hailstones. Hailstones can cause serious damage, notably to automobiles , aircraft, skylights, glass-roofed structures, livestock , and crops . Rarely, massive hailstones have been known to cause concussions or fatal head trauma . Hailstorms have been

3525-497: The direction the wind is coming from. The usage of the term in North America comes from the wind associated with many different types of storms, some of which can form in the North Atlantic Ocean and some of which form as far south as the Gulf of Mexico. The term is most often used in the coastal areas of New England and Atlantic Canada . This type of storm has characteristics similar to a hurricane . More specifically, it describes

3600-616: The extra water. Flash flooding can be hazardous to small infrastructure, such as bridges, and weakly constructed buildings. Plants and crops in agricultural areas can be destroyed and devastated by the force of raging water. Automobiles parked within experiencing areas can also be displaced. Soil erosion can occur as well, exposing risks of landslide phenomena. Like all forms of flooding phenomenon, flash flooding can also spread and produce waterborne and insect-borne diseases cause by microorganisms. Flash flooding can be caused by extensive rainfall released by tropical cyclones of any strength or

3675-561: The extremes of the historical distribution for a given area. Organized severe weather occurs under the same conditions that generate ordinary thunderstorms: atmospheric moisture, lift (often from thermals ), and instability . A wide variety of conditions cause severe weather. Several factors can convert thunderstorms into severe weather. For example, a pool of cold air aloft may aid in the development of large hail from an otherwise innocuous-appearing thunderstorm. The most severe hail and tornadoes are produced by supercell thunderstorms, and

3750-543: The eyes due to abrasion. Dust storms can many issues for agricultural industries as well. Soil erosion is one of the most common hazards and decreases arable lands . Dust and sand particles can cause severe weathering of buildings and rock formations. Nearby bodies of water may be polluted by settling dust and sand, killing aquatic organisms. Decrease in exposure to sunlight can affect plant growth, as well as decrease in infrared radiation may cause decreased temperatures. The most common cause of wildfires varies throughout

3825-606: The farmers reported, an average of one observer per 16–32 km. Telephone surveys were also conducted, resulting in observation densities as high as one report per 3 square kilometers. As a result, it is believed that only a very small percentage of hail reaching the surface went undetected. For the duration of the project, six categories were specified to size the observed hailstones conveniently: diameters less than 0.4 cm, 0.4–1.2 cm, 1.3–2.0 cm; 2.1–3.2 cm, 3.3–5.2 cm, and larger than 5.2 cm. Radiosondes were released from Penhold at 1715 local time (2315 UTC). Data were used to evaluate

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3900-428: The first recorded use of it for weather dates to 1829, when it was defined as a "violent blow". It achieved its modern definition by 1859, when it was in use in the western United States . The term became common in the press during the harsh winter of 1880–81. In the United States, storm systems powerful enough to cause blizzards usually form when the jet stream dips far to the south, allowing cold, dry polar air from

3975-419: The form of strong straight-line winds can be expected in areas where the squall line forms a bow echo , in the farthest portion of the bow. Tornadoes can be found along waves within a line echo wave pattern (LEWP) where mesoscale low-pressure areas are present. Intense bow echoes responsible for widespread, extensive wind damage are called derechos , and move quickly over large territories. A wake low or

4050-670: The frequency of the swaying bridge, the bridge may fail as occurred with the Tacoma Narrows Bridge in 1940. Hurricane-force winds, caused by individual thunderstorms, thunderstorm complexes, derechos, tornadoes, extratropical cyclones, or tropical cyclones can destroy mobile homes and structurally damage buildings with foundations. Winds of this strength due to downslope winds off terrain have been known to shatter windows and sandblast paint from cars. Once winds exceed 135 knots (250 km/h) within strong tropical cyclones and tornadoes, homes completely collapse, and significant damage

4125-467: The friction produced easily dissipates the winds. Strong horizontal winds will cause waterspouts to dissipate as they disturb the vortex. While not generally as dangerous as "classic" tornadoes, waterspouts can overturn boats, and they can cause severe damage to larger ships. Downbursts are created within thunderstorms by significantly rain-cooled air, which, upon reaching ground level, spreads out in all directions and produce strong winds. Unlike winds in

4200-453: The ground is lifted and blown by strong winds. The primary difference between a ground blizzard as opposed to a regular blizzard is that in a ground blizzard no precipitation is produced at the time, but rather all the precipitation is already present in the form of snow or ice at the surface. The Oxford English Dictionary concludes the term blizzard is likely onomatopoeic, derived from the same sense as blow, blast, blister, and bluster ;

4275-420: The ground. Downbursts also occur much more frequently than tornadoes, with ten downburst damage reports for every one tornado. A squall line is an elongated line of severe thunderstorms that can form along or ahead of a cold front . The squall line typically contains heavy precipitation , hail , frequent lightning , strong straight line winds, and possibly tornadoes or waterspouts . Severe weather in

4350-460: The main front to form a flanking front, or burn in the opposite direction of the main front by backing . Wildfires may also spread by jumping or spotting as winds and vertical convection columns carry firebrands (hot wood embers) and other burning materials through the air over roads, rivers, and other barriers that may otherwise act as firebreaks . Torching and fires in tree canopies encourage spotting, and dry ground fuels that surround

4425-513: The moist air. Tropical cyclones may produce torrential rain, high waves, and damaging storm surge . Heavy rains produce significant inland flooding. Storm surges may produce extensive coastal flooding up to 40 kilometres (25 mi) from the coastline. Although cyclones take an enormous toll in lives and personal property, they are also important factors in the precipitation regimes of areas they affect. They bring much-needed precipitation to otherwise dry regions. Areas in their path can receive

4500-820: The most destructive weather phenomena, are generally short-lived. A long-lived tornado generally lasts no more than an hour, but some have been known to last for 2 hours or longer (for example, the Tri-State Tornado ). Due to their relatively short duration, less information is known about the development and formation of tornadoes. Waterspouts are generally defined as tornadoes or non- supercell tornadoes that develop over bodies of water. Waterspouts typically do not do much damage because they occur over open water, but they are capable of traveling over land. Vegetation, weakly constructed buildings, and other infrastructure may be damaged or destroyed by waterspouts. Waterspouts do not generally last long over terrestrial environments as

4575-731: The north to clash with warm, humid air moving up from the south. When cold, moist air from the Pacific Ocean moves eastward to the Rocky Mountains and the Great Plains , and warmer, moist air moves north from the Gulf of Mexico , all that is needed is a movement of cold polar air moving south to form potential blizzard conditions that may extend from the Texas Panhandle to the Great Lakes and Midwest . A blizzard also may be formed when

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4650-448: The phenomena that accompany them form over wide geographic areas. These occurrences are classified as general severe weather . Downbursts and tornadoes are more localized and therefore have a more limited geographic effect. These forms of weather are classified as localized severe weather . The term severe weather is technically not the same phenomenon as extreme weather . Extreme weather describes unusual weather events that are at

4725-408: The previous dry season. This may cause soils that are sandy or composed of loam to become hydrophobic and repel water. Government organizations help their residents deal with wet-season floods though floodplain mapping and information on erosion control. Mapping is conducted to help determine areas that may be more prone to flooding. Erosion control instructions are provided through outreach over

4800-608: The size of the geographic area affected, whether it covers hundreds or thousands of square kilometers. High winds are known to cause damage, depending upon their strength. Wind speeds as low as 23 knots (43 km/h) may lead to power outages when tree branches fall and disrupt power lines. Some species of trees are more vulnerable to winds. Trees with shallow roots are more prone to uproot, and brittle trees such as eucalyptus , sea hibiscus , and avocado are more prone to branch damage. Wind gusts may cause poorly designed suspension bridges to sway. When wind gusts harmonize with

4875-458: The snow finally melted in late spring of 1881, huge sections of the plains experienced flooding. Massive ice jams clogged the Missouri River , and when they broke the downstream areas were inundated. Most of the town of Yankton , in what is now South Dakota, was washed away when the river overflowed its banks after the thaw. Many children—and their parents—learned of "The Snow Winter" through

4950-561: The spring thaw because the snow made the tracks impassable, the near-starvation of the townspeople, and the courage of her future husband Almanzo and another man, Cap Garland, who ventured out on the open prairie in search of a cache of wheat that no one was even sure existed. The Storm of the Century , also known as the Great Blizzard of 1993, was a large cyclonic storm that formed over the Gulf of Mexico on March 12, 1993, and dissipated in

5025-577: The sudden thawing effect of ice dams . Seasonal wind shifts lead to long-lasting wet seasons , which produce the bulk of annual precipitation in areas such as Southeast Asia, Australia, Western Africa, eastern South America, Mexico, and the Philippines. Widespread flooding occurs if rainfall is excessive, which can lead to landslides and mudflows in mountainous areas. Floods cause rivers to exceed their capacity with nearby buildings becoming submerged. Flooding may be exacerbated if there are fires during

5100-430: The telephone or the internet. Flood waters that occur during monsoon seasons can often host numerous protozoa , bacterial , and viral microorganisms. Mosquitoes and flies will lay their eggs within the contaminated bodies of water. These disease agents may cause infections of foodborne and waterborne diseases. Diseases associated with exposure to flood waters include malaria , cholera , typhoid , hepatitis A , and

5175-482: The weather that poses risks to life or property or requires the intervention of authorities. A narrower definition of severe weather is any weather phenomenon relating to severe thunderstorms . According to the World Meteorological Organization (WMO), severe weather can be categorized into two groups: general severe weather and localized severe weather. Nor'easters , European wind storms, and

5250-637: The wildfire season in the Western United States . Any form of thunderstorm that produces precipitating hailstones is known as a hailstorm. Hailstorms are generally capable of developing in any geographic area where thunderclouds ( cumulonimbus ) are present, although they are most frequent in tropical and monsoon regions. The updrafts and downdrafts within cumulonimbus clouds cause water molecules to freeze and solidify, creating hailstones and other forms of solid precipitation. Due to their larger density, these hailstones become heavy enough to overcome

5325-415: The wind. Dust storms frequently develop during periods of droughts, or over arid and semi-arid regions. Dust storms have numerous hazards and are capable of causing deaths. Visibility may be reduced dramatically, so risks of vehicle and aircraft crashes are possible. Additionally, the particulates may reduce oxygen intake by the lungs, potentially resulting in suffocation. Damage can also be inflicted upon

5400-468: The world. In the United States, Canada, and Northwest China, lightning is the major source of ignition. In other parts of the world, human involvement is a major contributor. For instance, in Mexico, Central America, South America, Africa, Southeast Asia, Fiji, and New Zealand, wildfires can be attributed to human activities such as animal husbandry , agriculture, and land-conversion burning. Human carelessness

5475-532: The worst downbursts and derechos (straight-line winds) are produced by bow echoes . Both of these types of storms tend to form in environments with high wind shear . Floods, hurricanes, tornadoes, and thunderstorms are considered to be the most destructive weather-related natural disasters . Although these weather phenomena are all related to cumulonimbus clouds , they form and develop under different conditions and geographic locations. The relationship between these weather events and their formation requirements

5550-563: Was centred on the Penhold radar site located near the Red Deer Airport ( 52°12′N 113°54′W  /  52.2°N 113.9°W  / 52.2; -113.9 ). The program had different ways of evaluating the atmospheric conditions for hail and its detection. Each spring, approximately 20,000 farmers in the project area would receive cards to record any event of hail, including its size. On days with hail, between 10 % and 20 % of

5625-428: Was prepared for deep snow so early in the winter. Farmers from North Dakota to Virginia were caught flat with fields unharvested, what grain that had been harvested unmilled, and their suddenly all-important winter stocks of wood fuel only partially collected. By January train service was almost entirely suspended from the region. Railroads hired scores of men to dig out the tracks but as soon as they had finished shoveling

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