(Eta analysis profile near Larned, Kansas, 00 UTC 3/24/00, updated by 23 UTC surface ob at GBD):
ICT
base refl 2331 UTC 3/23/00Tornadoes with mini-supercells
Mini-supercells typically have low LCL and LFC heights, and a large amount of low-level CAPE in their environments. Here is an extreme example.
Example 7. This is an unusual case. Storm
environments with 300+ J/kg of 0-3 km CAPE and the level of maximum buoyancy below 700
mb don't seem to occur that often. With so much buoyancy so close to the ground
and steep low-level lapse rates just above the ground, it may be relatively easy for
tornadoes to develop in such situations. In this case, a cold pool aloft and low
tropopause compressed buoyancy into low-levels so that the majority of CAPE in the profile
was below 3 km. An east-west windshift boundary provided focus and vorticity for
several small storms that behaved like mini-supercells, even without strong wind
shear. Several "surprise" tornadoes occurred in this case.
(Eta analysis profile near Larned, Kansas, 00 UTC 3/24/00, updated by 23 UTC surface ob at
GBD):
ICT
base refl 2331 UTC 3/23/00
Observed: Mini-supercells with several tornadoes, including an F1 with 13 mile track |
total ML CAPE 569 J/kg 0-1 km SRH 53 m2/s2 |
| parameter value | support for supercell tornadoes? | why? | comments | |
| 0-1k EHI | 0.2 | poor | < 1.0 | low-level thermodynamic |
| BL-6k shear | 24 kts | poor | < 30 kts | parameters are all unusually |
| LCL height | 161 m | strong | < 1000 m, very low | "strong" in this case, |
| with very low LCL & LFC heights | ||||
| CIN | 2 J/kg | strong | < 50 J/kg | and extreme CAPE |
| LFC height | 284 m | strong | < 1500 m, very low | in the lowest 3 km |
| 0-3k CAPE | 307 J/kg | very strong | > 90 J/kg, very large |
description and key for examples
operational low-level thermodynamic parameter guidelines