Supercells and Tornadoes What we’ll cover: Thunderstorm types Supercell characteristics Tornado Genesis Theory Storm Structure

Thunderstorm Categories Single Cell Multicell cluster Multicell line Supercell*

Single Cell Storms Typically last 20-30 minutes Typically not severe Cells producing a brief severe event are known as ‘pulse severe’ storms Usually disorganized Hard to forecast

Multicell cluster Most common type Each cell lasts about 20 minutes; cluster may last for several hours Consists of a group of cells moving along as one unit Each cell is usually at a different phase in it’s life cycle Mature cells found at center, dissipating found downwind Can produce moderate sized hail, flash floods and brief tornadoes

Multicell (Squall) Line Long line of storms with a continuous well-developed gust front at the leading edge of the line Can last for up to 12 hours Produce hail up to golf-ball size, heavy rainfall, and weak tornadoes, but they are best known for strong downdrafts Can also produce bow echoes

Supercell Definition a supercell is a convective storm that possesses a deep, persistent mesocyclone

Mesocyclones Definition A cyclonically rotating vortex, around 2–10 km in diameter, embedded within a convective storm

Supercell Highly organized thunderstorm A supercell is similar to the single-cell storm because they both have one main updraft updraft is extremely strong, reaching estimated speeds of 150-175 miles per hour main characteristic which sets the supercell apart from the other thunderstorm types is the presence of rotation

Supercell Produces giant hail more than 2 inches in diameter, strong downbursts of 80 miles an hour or more, and strong to violent tornadoes. Wind shear contributes to the severe nature of the storm

Wind Shear Two types Speed Shear Directional Shear

Supercell Categories Three standard types (though hybrids definitely occur) High Precipitation (HP) Classic Low Precipitation (LP)

HP Supercells Outflow (downdraft) dominant supercells Responsible for rain-wrapped tornadoes produce extreme and prolonged downburst events, serious flash flooding, and very large damaging hail events Most dangerous of all supercells

HP Supercell

Classic Supercells Visually well established and separate updraft and downdraft (precip core) regions

Classic Supercell

LP Supercells Hard or impossible to identify on radar Can produce large hail, weak to occasional strong tornadoes, weak to moderate intensity downdrafts, little rain

LP Supercell

Tornadogenesis

Tornadogenesis

Tornadogenesis

Chaser Terminology Bears cage CG Barber pole Beavers tail Cigar rolls Cored Sharks teeth Yahoo Roll cloud Whales mouth Shelf cloud Notch RFD cut Scud HDT’s Anvil splash Gustnadoes Dome Collar cloud Upside down Wedding cake Hail roar

Roll Cloud

Shelf Cloud

Whales Mouth

Upside Down Wedding Cake

Beaver Tail

Collar Cloud

Anvil (back)

Anvil (front)

Tornado

Tornado

Tornado

Tornado

Damage

Supercells

Supercells

Supercells

Supercells

Supercells

Supercells

Supercells

Supercells

Supercells