What is Derecho Storm System?

  9 July 2022.

Introduction:

On July 5, 2022, ‘Derecho Storm System’ hit the states of Minnesota, Nebraska, and Illinois in the United States.

Highlights:

• As the Derecho Storm System reached these state, speed of winds reached to around 140 km per hour.
• Winds knocked down the power lines as well as trees.
• The storm turned the skies into green, which was never witnessed.

About derecho

• As per National Weather Service of United States, derecho is a widespread, long-lived, straight-line windstorm.
• It is related to the ‘band of fast-moving showers or thunderstorms”.
• Its name has been derived from Spanish word ‘la derecha’ meaning ‘straight’ in English.
• Straight-line storms can be defined as the thunderstorm winds having no rotation.

Warm-Weather phenomenon

• Derecho is a warm-weather phenomenon.
•  It generally occurs during summertime starting May.
•  Mostly hit in June or July.
• It is a rare phenomenon, as opposed to other storm systems like tornadoes or hurricanes.

Which storm is classified as derecho?

• A storm having wind gusts of at least 93 km per hour, is classified as derecho. In such cases, damage area of winds reaches to over 400 km.
•  Gap between two successive wind damage events should not be greater than 3 hours.

Why did recent derecho in US turned skies green?

Skies are tuned green when light interacts with huge amount of water hold by them, during severe thunderstorms.

Types of derechos

Derechos are classified into three categories, namely progressive, serial and hybrid:

1. Progressive derecho– It is a summer phenomenon and it related to short line thunderstorms that travel for hundreds of miles, across a relatively narrow path.
2. Serial derecho– It commonly occurs during spring or fall. It has a wide & long squall line, which sweeps over large area.
3. Hybrid derecho– It has the features of progressive as well as serial derechos.

Areas of dominance

Derecho mostly commonly occur in central and eastern parts of United States. Derechos have also been reported in countries like Russia, Germany, Finland, Bulgaria and Poland.