"Woodward Oklahoma Supercell" by fireboat895 is licensed under CC BY 2.0

Unit 10

Supercells and tornadoes

Another severe mesoscale phenomenon are supercells. They differ in size, duration and severity from single-cell thunderstorms and may form tornadoes. Like multi-cell thunderstorms, supercells have a long duration and self-sustaining processes. In contrast to multi-cell storms, supercells have only one up- and one downdraft.

"Storm Chasing May 2014" by minds-eye is licensed under CC BY 2.0
“Storm Chasing May 2014” by minds-eye is licensed under CC BY 2.0

Learning goals

After completion of this units, students will be able to

  • Discuss the physical processes that lead to and go on over the lifetime of a supercell
  • Explain how supercell behavior is related to the ambient environment and synoptic scale forcing
  • Analyze weather maps, radio-soundings and radar data to predict when, and where supercells will occur, and whether or not supercells will develop
  • Explain supercell splitting, its role for storm rotation and movement of split supercells (graduate students)
  • Distinguish between single cell storms, multi-cell storms and super cells
  • Explain the differences between Alaska’s funnel clouds/tornadoes and tornadoes from supercells

Student tasks

  1. Watch this video on supercell formation, lifecycle and characteristics

  2. Watch this computer model visualizations of a supercell life cycle from formation over tornado development to dissipation
  3. Watch this video on the vorticity in a supercell storm
  4. All students: Read chapter 8.4 to 8.4.1 (included) and sections 8.5 to 8.5.3 (included) in Lin, Mesoscale Dynamics
  5. Graduate students: Read sections 8.4.2 to 8.4.5 (included) in Lin, Mesoscale Dynamics
  6. Solve the problems in this application task sheet, scan your results and submit them to cmoelders@alaska.edu

Supplemental material (optional)

13 May 2003 Hail Catastrophe: This case study deals with convective cells over Austria in a prefrontal unstable airmass causing expectionally intensive hail and a tornado in Vienna which is a rare phenomenon in this region.
NOAA tornadoes
More on radars
Oklahoma lightning dection array

Simulation of a storm
The NSSL COllaborative Model for Multiscale Atmospheric Simulation (COMMAS) is a 3D cloud model used to recreate thunderstorms for closer study. The simulation shows the early tornadic phase of the Greensburg, Kansas supercell that destroyed much of the city in 2004.

https://www.nssl.noaa.gov/tools/simulation

COMMAS model output: This animation shows cloud edge (gray), 40 dbZ volume (brown), vertical vorticity (blue), lightning (white and yellow volumes), and surface simulated radar reflectivity and wind vectors. (Note: no audio track, no captioning.)

More on tornadoes

© 2020 Nicole Mõlders | All rights reserved