2. Parameters

Stability Assessment » SWEAT Index Definition

Definition: SWEAT Index

The Severe Weather Threat (SWEAT) index differs from many of the other severe weather indices in that it takes into account the wind profile in assessing severe weather potential. Inputs include:

  • Total Totals index (TT)
  • 850 hPa dewpoint
  • 850 hPa wind speed and direction
  • 500 hPa wind speed and direction

In general, the following conditions lead to a higher SWEAT index and greater probability of severe weather:

  • Higher temperature and moisture at low levels
  • Cooler temperatures aloft
  • Large vertical wind shear
  • Wind direction veering with height

SWEAT index values have been empirically linked to convective events as follows:

SWEAT Severe Weather Potential
150-300 Slight severe
300-400 Severe possible
400 or greater Tornadic possible