Explosive cyclogenesis in the context of "Rapid deepening"

Cyclogenesis is the development or strengthening of cyclonic circulation in the atmosphere (a low-pressure area). Cyclogenesis is an umbrella term for at least three different processes, all of which result in the development of some sort of cyclone, and at any size from the microscale to the synoptic scale.

• Tropical cyclones form due to latent heat driven by significant thunderstorm activity, developing a warm core.
• Extratropical cyclones form as waves along weather fronts before occluding later in their life cycle as cold core cyclones.
• Mesocyclones form as warm core cyclones over land, and can lead to tornado formation. Waterspouts can also form from mesocyclones, but more often develop from environments of high instability and low vertical wind shear.

The process in which an extratropical cyclone undergoes a rapid drop in atmospheric pressure (24 millibars or more) in a 24-hour period is referred to as explosive cyclogenesis, and is usually present during the formation of a nor'easter. Similarly, a tropical cyclone can undergo rapid intensification.

The February 15–20, 2021 North American winter storm, also unofficially referred to as Winter Storm Viola, or to some as simply The North Texas Freeze, was a significant and widespread snow and ice storm across much of the United States, Northern Mexico, and Southern Canada. The system started out as a winter storm on the West Coast of the United States on February 15, later moving southeast into the Southern Plains and Deep South from February 16–17. It then moved into the Appalachian Mountains and Northeastern United States, before finally moving out to sea on February 20. The storm subsequently became a powerful low pressure system over the North Atlantic, before eventually dissipating on February 26.

The system resulted in over 170 million people being placed under winter weather alerts, stretching from the West Coast to the East Coast. Over 4 million people lost power due to the storm, particularly in areas of the Deep South and interior Southeast. The system worsened the 2021 Texas power crisis, causing additional major damage to the Texas power grid just days after another destructive winter storm came through the area and hampering recovery efforts. It also contributed to a historic cold wave that affected most of the Central United States. In total, the winter storm resulted in at least 29 fatalities, with 23 in the United States and six in Mexico. The system is estimated to have caused at least $2 billion (2021 USD) in damages, mainly due to blackouts and structural damage. Excluding the winter storm a few days previous to this storm, the system was the costliest winter storm in the United States since the March 1–3, 2018 nor'easter, and the deadliest since the Blizzard of 2016.