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Tornado Outbreak Of March 6–7, 2017
The tornado outbreak of March 6–7, 2017 was a widespread severe weather and tornado outbreak that affected portions of the Midwestern United States in the overnight hours of March 6–7. Occurring just days after a deadly and more significant event across similar areas just a week prior, this particular outbreak led to 63 tornadoes within a 9-hour period as a quasi-linear convective system and discrete supercell thunderstorms traversed the region. The most notable aspect of the outbreak was an EF3 tornado that damaged or destroyed hundreds of structures within Oak Grove, Missouri, injuring 12 people but causing no fatalities. An EF1 tornado touched down near Bricelyn, Minnesota, Bricelyn, the earliest known tornado on record in the state of Minnesota. Outside of tornadic activity, hundreds of damaging wind reports and a multitude of severe hail reports were documented. Meteorological synopsis On March 2, the Storm Prediction Center (SPC) highlighted the forecast evolutio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tornado Outbreak
__NOTOC__ A tornado outbreak is the occurrence of multiple tornadoes spawned by the same synoptic scale weather system. The number of tornadoes required to qualify as an outbreak typically are at least six to ten, with at least two rotational locations (if squall line) or at least two supercells producing multiple tornadoes. The tornadoes usually occur within the same day or continue into the early morning hours of the succeeding day, and within the same region. Most definitions allow for a break in tornado activity (time elapsed from the end of the last tornado to the beginning of the next tornado) of six hours. If tornado activity indeed resumes after such a lull, many definitions consider the event to be a new outbreak. A series of continuous or nearly continuous tornado outbreak days is a tornado outbreak sequence. In the United States and Canada, tornado outbreaks usually occur from March through June in the Great Plains, the Midwestern United States, and the Southeastern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trough (meteorology)
A trough is an elongated region of relatively low atmospheric pressure without a closed isobaric contour that would define it as a low pressure area. Since low pressure implies a low height on a pressure surface, troughs and ridges refer to features in an identical sense as those on a topographic map. Troughs may be at the surface, or aloft. Near-surface troughs sometimes mark a weather front associated with clouds, showers, and a wind direction shift. Upper-level troughs in the jet stream (as shown in diagram) reflect cyclonic filaments of vorticity. Their motion induces upper-level wind divergence, lifting and cooling the air ahead (downstream) of the trough and helping to produce cloudy and rain conditions there. Unlike fronts, there is not a universal symbol for a trough on a surface weather analysis chart. The weather charts in some countries or regions mark troughs by a line. In the United States, a trough may be marked as a dashed line or bold line. In the UK, Hong Kong ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atmospheric Instability
Atmospheric instability is a condition where the Earth's atmosphere is generally considered to be unstable and as a result the weather is subjected to a high degree of variability through distance and time. Atmospheric stability is a measure of the atmosphere's tendency to discourage or deter vertical motion, and vertical motion is directly correlated to different types of weather systems and their severity. In unstable conditions, a lifted thing, such as a parcel of air will be warmer than the surrounding air at altitude. Because it is warmer, it is less dense and is prone to further ascent. In meteorology, instability can be described by various indices such as the Bulk Richardson Number, lifted index, K-index, convective available potential energy (CAPE), the Showalter, and the Vertical totals. These indices, as well as atmospheric instability itself, involve temperature changes through the troposphere with height, or lapse rate. Effects of atmospheric instability in mois ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Warm Front
A warm front is a density discontinuity located at the leading edge of a homogeneous warm air mass, and is typically located on the equator-facing edge of an isotherm gradient. Warm fronts lie within broader troughs of low pressure than cold fronts, and move more slowly than the cold fronts which usually follow because cold air is denser and less easy to remove from the Earth's surface. This also forces temperature differences across warm fronts to be broader in scale. Clouds ahead of the warm front are mostly stratiform, and rainfall defiantly increases as the front approaches. Fog can also occur preceding a warm frontal passage. Clearing and warming is usually rapid after frontal passage. If the warm air mass is unstable, thunderstorms may be embedded among the stratiform clouds ahead of the front, and after frontal passage thundershowers may continue. On weather maps, the surface location of a warm front is marked with a red line of semicircles pointing in the direction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dry Line
A dry line (also called a dew point line, or Marfa front, after Marfa, Texas) is a line across a continent that separates moist air and dry air. One of the most prominent examples of such a separation occurs in central North America, especially Texas, Oklahoma, and Kansas, where the moist air from the Gulf of Mexico meets dry air from the desert south-western states. The dry line is an important factor in severe weather frequency in the Great Plains of North America. It typically lies north-south across the High Plains states in the warm sector of an extratropical cyclone and stretches into the Canadian Prairies during the spring and early summer. The dry line is also important for severe convective storms in other regions of the world, such as northern India. In general, thunderstorms and other forms of severe weather occur on the moist side of the dryline. Characteristics Near the surface, warm dry air is denser than warm moist air of lesser or similar temperature, and thus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Warm Front
A warm front is a density discontinuity located at the leading edge of a homogeneous warm air mass, and is typically located on the equator-facing edge of an isotherm gradient. Warm fronts lie within broader troughs of low pressure than cold fronts, and move more slowly than the cold fronts which usually follow because cold air is denser and less easy to remove from the Earth's surface. This also forces temperature differences across warm fronts to be broader in scale. Clouds ahead of the warm front are mostly stratiform, and rainfall defiantly increases as the front approaches. Fog can also occur preceding a warm frontal passage. Clearing and warming is usually rapid after frontal passage. If the warm air mass is unstable, thunderstorms may be embedded among the stratiform clouds ahead of the front, and after frontal passage thundershowers may continue. On weather maps, the surface location of a warm front is marked with a red line of semicircles pointing in the direction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cold Front
A cold front is the leading edge of a cooler mass of air at ground level that replaces a warmer mass of air and lies within a pronounced surface trough of low pressure. It often forms behind an extratropical cyclone (to the west in the Northern Hemisphere, to the east in the Southern), at the leading edge of its cold air advection pattern—known as the cyclone's dry "conveyor belt" flow. Temperature differences across the boundary can exceed from one side to the other. When enough moisture is present, rain can occur along the boundary. If there is significant instability along the boundary, a narrow line of thunderstorms can form along the frontal zone. If instability is weak, a broad shield of rain can move in behind the front, and evaporative cooling of the rain can increase the temperature difference across the front. Cold fronts are stronger in the fall and spring transition seasons and are weakest during the summer. Development of cold fronts A cold front occurs wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Dakotas
The Dakotas is a collective term for the U.S. states of North Dakota and South Dakota. It has been used historically to describe the Dakota Territory, and is still used for the collective heritage, culture, geography, fauna, sociology, economy, and cuisine among the two states. Etymology The name Dakota refers to the Dakota people. History The territory now known as the Dakotas includes a large portion of the ancestral land of Native American tribes, in particular various tribes of Sioux such as the Dakota people, also known as the Santee Sioux. The United States government stakes its claim to the land through the Louisiana Purchase and Rupert's Land accusation. The region historically involved a complex series of conflicts between the US government and Native American tribes (and among themselves). For a while the region consisted of the Minnesota and Nebraska territories until in 1861, the US government formed the Dakota Territory, which included both the modern states ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Low-pressure Area
In meteorology, a low-pressure area, low area or low is a region where the atmospheric pressure is lower than that of surrounding locations. Low-pressure areas are commonly associated with inclement weather (such as cloudy, windy, with possible rain or storms), while high-pressure areas are associated with lighter winds and clear skies. Winds circle anti-clockwise around lows in the northern hemisphere, and clockwise in the southern hemisphere, due to opposing Coriolis force, Coriolis forces. Low-pressure systems form under areas of wind divergence that occur in the upper levels of the Atmosphere of Earth, atmosphere (aloft). The formation process of a low-pressure area is known as cyclogenesis. In Meteorology#Dynamic meteorology, meteorology, atmospheric divergence aloft occurs in two kinds of places: * The first is in the area on the east side of upper Trough (meteorology), troughs, which form half of a Rossby wave within the Westerlies (a trough (meteorology), trough with la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shortwave (meteorology)
A shortwave or shortwave trough is an embedded kink in the trough / ridge pattern. Its length scale is much smaller than that of and is embedded within longwaves, which are responsible for the largest scale (synoptic scale) weather systems. Shortwaves may be contained within or found ahead of longwaves and range from the mesoscale to the synoptic scale. Shortwaves are most frequently caused by either a cold pool or an upper level front. Shortwaves are commonly referred to as a vorticity maximum. Corresponding weather and effects Shortwaves are often associated with warm air advection (WAA) or cold air advection (CAA), which influence temperature. Due to the way they move the air around them and the way air moves away from them, shortwaves produce positive curvature vorticity and positive shear vorticity, respectively. Ahead of a shortwave there is large-scale lift due to divergence from positive vorticity advection (PVA). This lift often causes precipitation. In a capped ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Four Corners
The Four Corners is a region of the Southwestern United States consisting of the southwestern corner of Colorado, southeastern corner of Utah, northeastern corner of Arizona, and northwestern corner of New Mexico. The Four Corners area is named after the quadripoint at the intersection of approximately 37° north latitude with 109° 03' west longitude, where the boundaries of the four states meet, and are marked by the Four Corners Monument. It is the only location in the United States where four states meet. Most of the Four Corners region belongs to semi-autonomous Native American nations, the largest of which is the Navajo Nation, followed by Hopi, Ute, and Zuni tribal reserves and nations. The Four Corners region is part of a larger region known as the Colorado Plateau and is mostly rural, rugged, and arid. In addition to the monument, commonly visited areas within Four Corners include Monument Valley, Mesa Verde National Park, Chaco Canyon, Canyons of the Ancie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
