Hail is a form of solid precipitation. It is distinct from ice pellets, though the two are often confused. It consists of balls or irregular lumps of ice, each of which is called a hailstone. Ice pellets generally fall in cold weather, while hail growth is greatly inhibited during low surface temperatures.
A tornado is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, although the word cyclone is used in meteorology to name a weather system with a low-pressure area in the center around which, from an observer looking down toward the surface of the Earth, winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern. Tornadoes come in many shapes and sizes, and they are often visible in the form of a condensation funnel originating from the base of a cumulonimbus cloud, with a cloud of rotating debris and dust beneath it. Most tornadoes have wind speeds less than 180 kilometers per hour, are about 80 meters across, and travel several kilometers before dissipating. The most extreme tornadoes can attain wind speeds of more than 480 kilometers per hour (300 mph), are more than 3 kilometers (2 mi) in diameter, and stay on the ground for more than 100 km.
A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorms are sometimes called thundershowers. Thunderstorms occur in a type of cloud known as a cumulonimbus. They are usually accompanied by strong winds and often produce heavy rain and sometimes snow, sleet, or hail, but some thunderstorms produce little precipitation or no precipitation at all. Thunderstorms may line up in a series or become a rainband, known as a squall line. Strong or severe thunderstorms include some of the most dangerous weather phenomena, including large hail, strong winds, and tornadoes. Some of the most persistent severe thunderstorms, known as supercells, rotate as do cyclones. While most thunderstorms move with the mean wind flow through the layer of the troposphere that they occupy, vertical wind shear sometimes causes a deviation in their course at a right angle to the wind shear direction.
A supercell is a thunderstorm characterized by the presence of a mesocyclone: a deep, persistently rotating updraft. Due to this, these storms are sometimes referred to as rotating thunderstorms. Of the four classifications of thunderstorms, supercells are the overall least common and have the potential to be the most severe. Supercells are often isolated from other thunderstorms, and can dominate the local weather up to 32 kilometres (20 mi) away. They tend to last 2–4 hours.
A severe thunderstorm watch is a severe weather watch product of the National Weather Service that is issued by regional offices of weather forecasting agencies throughout the world when meteorological conditions are favorable for the development of severe thunderstorms as defined by regional criteria that may contain large hail, straight-line winds, lightning, intense hydrological phenomena and/or tornadoes. A severe thunderstorm watch does not necessarily mean that severe weather is actually occurring, only that conditions present a credible risk for thunderstorms producing severe weather phenomena to affect portions of the watch area. A watch must not be confused with a severe thunderstorm warning.
A severe thunderstorm warning is a severe weather warning product of the National Weather Service that is issued by regional offices of weather forecasting agencies throughout the world to alert the public that severe thunderstorms are imminent or occurring. A severe thunderstorm warning is issued when Doppler weather radar, trained storm spotters or local emergency management personnel indicate that a thunderstorm is producing large hail and high winds capable of causing significant damage, and is expected to continue producing severe weather along the storm's projected track. Flooding is also sometimes caused by torrential rainfall produced by a thunderstorm.
A hook echo is a pendant or hook-shaped weather radar signature as part of some supercell thunderstorms. It is found in the lower portions of a storm as air and precipitation flow into a mesocyclone, resulting in a curved feature of reflectivity. The echo is produced by rain, hail, or even debris being wrapped around the supercell. It is one of the classic hallmarks of tornado-producing supercells. The National Weather Service may consider the presence of a hook echo coinciding with a tornado vortex signature as sufficient to justify issuing a tornado warning.
Severe storms in Australia refers to the storms, including cyclones, which have caused severe damage in Australia. For comparison, a comprehensive list of all damaging storms can be found on the Australian Bureau of Meteorology website.
The Bucca tornado was one of the most violent tornadoes ever observed in Australia, being the first Australian tornado to be officially rated F4 on the Fujita scale. It occurred near the township of Bucca in Queensland on 29 November 1992 at around 2:20pm AEST. The tornado was accompanied by cricket-ball sized hail across Bucca and Bullyard regions.
Severe weather is any dangerous meteorological phenomenon with the potential to cause damage, serious social disruption, or loss of human life. Types of severe weather phenomena vary, depending on the latitude, altitude, topography, and atmospheric conditions. High winds, hail, excessive precipitation, and wildfires are forms and effects of severe weather, as are thunderstorms, downbursts, tornadoes, waterspouts, tropical cyclones, and extratropical cyclones. Regional and seasonal severe weather phenomena include blizzards (snowstorms), ice storms, and duststorms. Extreme weather phenomena that cause extreme heat, cold, wetness or drought often will bring severe weather events. One of the principal effects of anthropogenic climate change is changes in severe and extreme weather patterns.
Atmospheric convection is the result of a parcel-environment instability, or temperature difference layer in the atmosphere. Different lapse rates within dry and moist air masses lead to instability. Mixing of air during the day which expands the height of the planetary boundary layer leads to increased winds, cumulus cloud development, and decreased surface dew points. Moist convection leads to thunderstorm development, which is often responsible for severe weather throughout the world. Special threats from thunderstorms include hail, downbursts, and tornadoes.
Convective storm detection is the meteorological observation, and short-term prediction, of deep moist convection (DMC). DMC describes atmospheric conditions producing single or clusters of large vertical extension clouds ranging from cumulus congestus to cumulonimbus, the latter producing thunderstorms associated with lightning and thunder. Those two types of clouds can produce severe weather at the surface and aloft.
The 1999 Sydney hailstorm was the costliest natural disaster in Australian insurance history, causing extensive damage along the east coast of New South Wales. The storm developed south of Sydney on the afternoon of Wednesday, 14 April 1999, and struck the city's eastern suburbs, including the central business district, later that evening.
The 1947 Sydney hailstorm was a natural disaster which struck Sydney, Australia, on 1 January 1947. The storm cell developed on the morning of New Year's Day, a public holiday in Australia, over the Blue Mountains, hitting the city and dissipating east of Bondi in the mid-afternoon. At the time, it was the most severe storm to strike the city since recorded observations began in 1792.
The 2010 Victorian storms were a series of storms that passed through much of the Australian state of Victoria on 6 and 7 March 2010. One of the most severe storms passed directly over Greater Melbourne, bringing lightning, flash flooding, very large hail and strong winds to the state's capital.
This page documents the tornadoes and tornado outbreaks of 2013. Strong and destructive tornadoes form most frequently in the United States, Bangladesh, Brazil and Eastern India, but they can occur almost anywhere under the right conditions. Tornadoes also appear regularly in neighboring southern Canada during the Northern Hemisphere's summer season, and somewhat regularly in Europe, Asia, and Australia.
The following is a glossary of tornado terms. It includes scientific as well as selected informal terminology.
The 2014 Brisbane hailstorm struck Brisbane, the capital city of Queensland, Australia on 27 November 2014. The storm caused severe damage to many buildings and cars in the city. Around 40 people were injured. Wind speeds of 141 km/h (88 mph) were recorded with multiple reports of hail in the city and surrounding areas.
Severe storm events in Sydney, New South Wales, Australia are not uncommon and include hailstorms, wind storms, and flash flooding from rain caused by East coast lows, black nor'easters and/or tropical cyclone remnants. East coast lows are low pressure depressions or extratropical cyclones that can bring significant damage by heavy rain, cyclonic winds and huge swells. Sydney is rarely affected by cyclones, although remnants of cyclones do affect the city.
