least 100 km (60 miles) wide and 650 km (400 miles) long. A great visual example of a derecho was made available by time-lapse imagery from satellites operated by the National Oceanic and Atmospheric Association, which clearly recorded the outer boundary layer of a derecho and the intensity of associated lightning strikes quickly moving eastward in Midwestern states on 10 August 2020. In order to be classified as a derecho, a wind storm must meet the following criteria Wind damage swath extending for more than Wind gusts of at least along most of its length Several, well-separated or greater gusts Four types of derechos are generally recognized: Serial derecho – This type of derecho is usually associated with a very deep low. Single-bow – A very large bow echo around or upwards of long. This type of serial derecho is less common than the multi-bow kind. An example of a single-bow serial derecho is the derecho that occurred in association with the October 2010 North American storm complex. Multi-bow – Multiple bow derechos are embedded in a large squall line typically around long. One example of a multi-bow serial derecho is a derecho that occurred during the 1993 Storm of the Century in Florida. Because of embedded supercells, tornadoes can spin out of these types of derechos. This is a much more common type of serial derecho than the single-bow kind. Multi-bow serial derechos can be associated with line echo wave patterns (LEWPs) on weather radar. Progressive derecho – A line of thunderstorms take the bow-shape and may travel for hundreds of miles along stationary fronts. Examples of this include "Hurricane Elvis" in 2003 and the Boundary Waters-Canadian Derecho of 4–5 July 1999. Tornado formation is less common in a progressive than serial type. Hybrid derecho – A derecho with characteristics of both a serial and progressive derecho. Similar to serial derechos and progressive derechos, these types of derechos are associated with a deep low, but are relatively small in size. An example is the Late-May 1998 tornado outbreak and derecho that moved through the central Northern Plains and the Southern Great Lakes on 30–31 May 1998. Low dewpoint derecho – A derecho that occurs in an environment of comparatively limited low-level moisture, with appreciable moisture confined to the mid-levels of the atmosphere. Such derechos most often occur between late fall and early spring in association with strong low-pressure systems.