Supercell
Introduction
A supercell is a type of thunderstorm that is characterized by the presence of a mesocyclone: a deep, persistently rotating updraft. It is considered the most severe of all thunderstorm types. Supercells are often isolated from other thunderstorms, and can dominate the local weather up to 32 kilometers (20 mi) away.
Structure
Supercells are usually found isolated from other thunderstorms, although they can sometimes be embedded in a squall line. Typically, supercells are found in the warm sector of a low-pressure system propagating generally in a north easterly direction in line with the cold front of the low pressure system.
Mesocyclone
The primary distinguishing characteristic of a supercell is the presence of a deep and persistent rotating updraft, known as a mesocyclone. If the mesocyclone is strong and persistent, the supercell may evolve into a tornadic supercell, producing tornadoes.
Updraft and Downdraft
A supercell thunderstorm's structure is characterized by a strong, rotating updraft that can reach speeds of over 150 mph (240 km/h). This updraft can persist for hours, leading to severe weather conditions. The downdraft in a supercell is also particularly strong, and can cause damaging winds at the surface.
Dynamics
The dynamics of a supercell are complex and involve numerous processes. These include the interaction of the updraft and downdraft, the development and maintenance of the mesocyclone, and the interaction of the storm with its environment.
Updraft and Downdraft Interaction
The interaction between the updraft and downdraft in a supercell is a key factor in its development and maintenance. The updraft carries warm, moist air upward, while the downdraft carries cooler, drier air downward. This interaction can lead to the development of a mesocyclone.
Mesocyclone Development and Maintenance
The development and maintenance of a mesocyclone within a supercell is a complex process that involves the interaction of the updraft and downdraft, as well as the rotation of the storm itself. The rotation is caused by wind shear in the storm's environment, and can be intensified by the updraft.
Interaction with the Environment
The interaction of a supercell with its environment can influence its development and behavior. For example, the presence of wind shear in the storm's environment can enhance the rotation of the storm and contribute to the development of a mesocyclone.
Types of Supercells
There are several types of supercells, classified primarily by their mesocyclone structure and the nature of their updrafts and downdrafts. These include the classic supercell, the low-precipitation (LP) supercell, and the high-precipitation (HP) supercell.
Classic Supercell
The classic supercell is characterized by a strong, persistent mesocyclone and a balanced updraft and downdraft. It often produces severe weather, including large hail, strong winds, and tornadoes.
Low-Precipitation (LP) Supercell
The low-precipitation (LP) supercell is characterized by a high base and relatively little precipitation. It often produces large hail and strong winds, but tornadoes are less common.
High-Precipitation (HP) Supercell
The high-precipitation (HP) supercell is characterized by a low base and heavy precipitation. It often produces strong winds and flash flooding, but large hail and tornadoes are less common.
Hazards
Supercells are capable of producing severe weather, including large hail, strong winds, flash flooding, and tornadoes. The hazards associated with supercells can cause significant damage and pose a threat to life and property.
Large Hail
Supercells are capable of producing large hail, with diameters of 1 inch (2.5 cm) or more. This hail can cause significant damage to property, including vehicles and buildings, and can injure or kill people and animals.
Strong Winds
Supercells can produce strong winds, often exceeding 58 mph (93 km/h). These winds can cause damage to property and pose a threat to life.
Flash Flooding
High-precipitation (HP) supercells can produce heavy rainfall, leading to flash flooding. This can cause damage to property and pose a threat to life, particularly in low-lying areas.
Tornadoes
Supercells are the most common type of storm to produce tornadoes. These tornadoes can cause significant damage and pose a serious threat to life.