Iowa Governor Reynolds requested $4 billion in federal aid to assist in the recovery efforts. A derecho (/dəˈreɪtʃoʊ/, from Spanish: derecho [deˈɾetʃo], "straight" as in direction) is a widespread, long-lived, straight-line wind storm that is associated with a fast-moving group of severe thunderstorms known as a mesoscale convective system and potentially rivaling hurricanic and tornadic forces. Within minutes, extremely high winds can arise, strong enough to knock over highway signs and topple large trees. Advisory/Warning Criteria, Radar Gust fronts often are marked by a band of ominous, low clouds known as "arcus." An area of convection developed across eastern Iowa near a weak stationary/warm front and ultimately matured, taking on the shape of a wavy squall line across western Ohio and southern Indiana. When the convection is strongly linear or slightly curved, the MCS is called a squall line, with the strongest winds typically occurring just behind the leading edge of the significant wind shift and pressure rise.. Only in 40 to 65 percent or so of the United States resting on the coast of the Atlantic basin, and a fraction of the Everglades, are derechos surpassed in this respect — by landfalling hurricanes, which at their worst may have winds as severe as EF3 tornadoes. During the cool season (September through April), derechos are relatively infrequent but are most likely to occur from east Texas into the southeastern states. Hazardous Weather Outlook  The size of the bow may vary, and the storms associated with the bow may die and redevelop. 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. A derecho (pronounced similar to "deh-REY-cho") is a widespread, long-lived wind storm that is associated with a band of rapidly moving showers or thunderstorms. It is dangerous to drive under these conditions, especially at night, because of blowing debris and obstructed roadways.  Over a million homes across the Midwest were without basic services such as water and electricity. At this point, widespread and persistent wind damage has been occurring for a prolonged period of time. Therefore, a progressive derecho can quickly develop with very little warning. Local Climate Pages Downed wires and widespread power outages are likely but not always a factor. Janssen, Kim, Mitch Dudek and Stefano Esposito, October 2010 North American storm complex, Late-May 1998 tornado outbreak and derecho, National Oceanic & Atmospheric Administration, "A Proposed Revision to the Definition of "Derecho, "A Brief History of Gustavus Hinrichs, Discoverer of the Derecho", "Severe Thunderstorm Forecasting: A Historical Perspective", 10.1175/1520-0434(1986)001<0164:STFAHP>2.0.CO;2, "Interpreting the Climatology of Derechos", 10.1175/1520-0434(2004)019<0595:ITCOD>2.0.CO;2, National Oceanic and Atmospheric Administration, "The Utah-Wyoming derecho of May 31, 1994", "What was the Largest Hurricane to Hit the United States? Bow echoes most frequently occur when atmospheric winds are relatively strong and unidirectional (i.e., they vary little in direction with height but increase in speed). In order to be classified as a derecho, the storm complex must travel a … Therefore, the most favorable area for this type of storm to develop is on the periphery of a strong area of high pressure aloft where the greatest overlap of hot and dry conditions and stronger wind aloft occurs. , The August 2020 Midwest Derecho delivered a maximum measured wind speed of 126 mph, with damage-estimated speeds as high as 140 mph in the Cedar Rapids, Iowa area. The event is known as a derecho. 1-Stop Winter Forecast Storm Prediction Center [clarification needed] The convection tends to move east or toward the equator, roughly parallel to low-level thickness lines and usually somewhat to the right of the mean tropospheric flow. Derechos can cause hurricane-force winds, tornadoes, heavy rains, and flash floods. Station History . They may have a central eye free of precipitation, with a minimum central pressure and surrounding bands of strong convection, but are really associated with an MCS developing multiple squall lines, and are not tropical in nature. Jackson Although these storms most commonly occur in North America, derechos can occur elsewhere in the world, with a few areas relatively frequently. , With the average tornado in the United States and Canada rating in the low end of the F/EF1 classification at 38 to 45 m/s (137 to 161 km/h; 74 to 87 kn; 85 to 100 mph) peak winds and most or all of the rest of the world even lower, derechos tend to deliver the vast majority of extreme wind conditions over much of the territory in which they occur. These winds are accompanied by spraying rain and frequent lightning from all directions.  Datasets compiled by the United States National Weather Service and other organizations show that a large swath of the north-central United States, and presumably at least the adjacent sections of Canada and much of the surface of the Great Lakes, can expect winds from 38 to 54 m/s (137 to 193 km/h; 74 to 104 kn; 85 to 120 mph) over a significant area at least once in any 50-year period, including both convective events and extra-tropical cyclones and other events deriving power from baroclinic sources. With the bow may vary, and downburst clusters embedded inside the storm Prediction center 's derechos. To derecho storms when what is a derecho storm conditions are in place often occur along stationary fronts on the northern periphery of the... 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