December 17, 2021 - Derecho Sweeps across Midwest

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Dust in Colorado, Kansas, Oklahoma, Texas
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An anomalous and historic December derecho—a windstorm associated with
an unusually strong and fast-moving line of thunderstorms—swept from
the U.S. Southwest to the Upper Midwest on December 15, 2021. High-wind
warnings were issued from the Central and Southern High Plains to the
Great Lakes, including storm warnings over the Great Lakes.

The storm brought hurricane-force winds, dust storms, tornadoes,
wildfires, snow squalls, and heavy rain across the middle of the
country. Hundreds of thousands of homes and businesses lost electric
power, and roughly 100 million Americans were under some type of
weather warning that day.

The Moderate Resolution Imaging Spectroradiometer (MODIS) on board
NASA’s Aqua satellite acquired a true-color image of the first part of
the storm, on December 15, when strong winds kicked up a thick and
widespread blanket of dust. At the time the image was captured, the
dust covered parts of Texas, Colorado, Oklahoma, and Kansas, obscuring
visibility on the ground and hiding the ground from view from space.

The derecho was spawned by the interaction of a deep-low pressure
system over the Northern High Plains and a high-pressure system to the
west. This created a tight pressure gradient over the Rocky Mountains
that generated fierce winds. The storm generated at least 55
hurricane-force gusts (those exceeding 75 miles per hour), breaking the
previous one-day record (since tracking began in 2004). All previous
records were set during the summer months. According to the National
Weather Service, a derecho is a widespread, long-lived wind storm that
is associated with a band of rapidly moving showers or thunderstorms.
If the wind damage swath extends more than 240 miles (about 400 km) and
includes wind gust of at least 58 mph (93 km/h) or greater along most
of its length, then the event meets the classification of a derecho.

In Colorado, wind gusts exceeded 100 miles (160 kilometers) per hour
and dust storms swirled in southeastern part of the state and in
western Kansas. Snow and rain showers, along with at least 20
tornadoes, were reported along the squall line.

Meanwhile, ahead of the front, parts of the Southern Plains into the
Upper Midwest saw record-breaking warm temperatures. In Wisconsin and
Iowa, temperatures reached above 70 degrees Fahrenheit (21° Celsius).
The heat and the high winds also prompted extreme fire weather warnings
for parts of the Central and Southern Plains, as wildfires broke out in
Kansas, Texas, and Oklahoma.

Image Facts
Satellite: Aqua
Date Acquired: 12/15/2021
Resolutions: 1km (1005 KB), 500m (2.6 MB), 250m (1.8 MB)
Bands Used: 1,4,3
Image Credit: MODIS Land Rapid Response Team, NASA GSFC



https://modis.gsfc.nasa.gov/gallery/individual.php?db_date=2021-12-17

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