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[1] [7] In Australia, a squall is defined to last for several minutes before the wind returns to the long-term mean value. [3] In either case, a squall is defined to last about half as long as the definition of sustained wind in its respective country. Usually, this sudden violent wind is associated with briefly heavy precipitation as squall ...
The leading area of a squall line is composed primarily of multiple updrafts, or singular regions of an updraft, rising from ground level to the highest extensions of the troposphere, condensing water and building a dark, ominous cloud to one with a noticeable overshooting top and anvil (thanks to synoptic scale winds).
A shelf cloud, such as this one, can be a sign that a squall is imminent. A mesoscale convective system (MCS) is a complex of thunderstorms that becomes organized on a scale larger than the individual thunderstorms but smaller than extratropical cyclones, and normally persists for several hours or more.
A snow squall is a brief period of intense snowfall and wind that leads to whiteout conditions which could trigger dangerous traffic accidents. Snow squalls are most common in the northern United ...
Linear snow squall bands produce more thundersnow than clustered bands; thus a directional wind shear with a change of less than 12° between the ground and 2,000 m (6,600 ft) in height must be in place. However, any change in direction greater than 12° through that layer will tear the snow squall apart.
Squall lines typically "bow out" due to the formation of a mesoscale high-pressure system which forms within the stratiform rain area behind the initial convective line. This high-pressure area is formed due to strong descending air currents behind the squall line, and could come in the form of a downburst . [ 10 ]
A snow squall, or snowsquall, is a sudden moderately heavy snowfall with blowing snow and strong, gusty surface winds. [1] It is often referred to as a whiteout and is similar to a blizzard but is localized in time or in location and snow accumulations may or may not be significant.
Rainbands in advance of warm occluded fronts and warm fronts are associated with weak upward motion, [1] and tend to be wide and stratiform in nature. [2] In an atmosphere with rich low level moisture and vertical wind shear, [3] narrow, convective rainbands known as squall lines form generally in the cyclone's warm sector, ahead of strong cold fronts associated with extratropical cyclones. [4]