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Severe Weather Threat Index calculator



Enter the 850 hPa dewpoint (C)
Enter the Total totals Index (C)
Enter the 850 hPa windspeed (kts)
Enter the 500 hPa windspeed (kts)
Enter the S value (see below)
The SWEAT Index is


S value to be found via  formula : sin(dd500-dd850)

(dd = wind direction (at 500 or 850 hPa))

All members must have positive values, otherwise set it to 0.
Last member = 0, unless
dd500-dd850 >0
V850 and V500 =>15kts


SWEAT  >300   moderate potential for severe thunderstorms.
SWEAT  >500   high potential for severe thunderstorms.

The SWEAT index is designed to predict severe storms, rather than ordinary thunderstorms. Unreliable results on higher elevations. Tests on the field (in the States) showed a poor correlation between high SWEAT values and severe weather events.


Formula used: SWEAT = 12xTd850 + 20x(TT-49) +2x1.94xV850 + 1.94xV500 + 125x(S+0.2)



Note: Java script must be enabled