|
Lifted Index | Marginal 0 to -3 |
Moderate -3 to -6 |
Very
Unstable -6 to -9 |
Extreme < -9 |
CAPE | Weak < 1000 J/kg |
Moderate 1000 to 2500 J/kg |
Very
Unstable 2500 to 3500 J/kg |
Extreme > 3500 J/kg |
LFC Height | < 2,000
meters tornadoes more likely with supercells. < 3,000 meters thunderstorms are more easily initiated. |
|||
Surface to 1 km Shear | > 15 to 20 knots Favors supercell thunderstorms. | |||
Surface to 6 km Shear | 35 to 40 knots associated with supercell thunderstorms. | |||
Effective Bulk Shear | 25 to 40 knots associated with supercell thunderstorms. | |||
BRN Shear | 35 to 40 knots associated with supercell thunderstorms. | |||
0 to 1km SR Helicity | > 100 suggests increased threat of tornadoes with supercells | |||
0 to 3 SR Helicity | > 250 suggests increased threat of tornadoes with supercells | |||
Storm-relative Helicity |
Supercell Threshold 150 |
Weak
Tornadoes 150 to 299 |
Strong
Tornadoes 300 to 449 |
Violent
Tornadoes > 450 |
Surface to 2 km SR Winds | > 15 to 20 Favors sustained supercell thunderstorms. | |||
4 to 6 km SR Winds | > 15 Favors tornadic supercell thunderstorms. | |||
9 to 11 km SR Winds | HP
Supercells < 40 |
Classic
Supercells 40 to 60 |
Low Precipitation > 60 |
|
Significant Hail Parameter | > 1.5 to 2.0 Favors hail greater than 2" in diameter. | |||
Supercell Composite | Marginal 1.2 |
Non-Tornadic 3.2 |
Weak
Tornado 5.7 |
Sig.
Tornado 10 |
Significant Tornado | > 1 Associated with significant tornadoes. | |||
Energy Helicity Index |
< 1 supercells & tornadoes unlikely 1 to 2 supercells and tornadoes possible 2 to 2.4 supercells likely and tornadoes possible 2.5 to 2.9 supercell tornadoes likely 3 to 3.9 strong tornadoes possible > 4 violent tornadoes possible |