SWEAT Index

[jrleeman]

Another severe weather index. From COD: http://weather.cod.edu/sirvatka/si.html

SWEAT Index

SWEAT = 12Td850 + 20(TT - 49) + 2f850 + f500 + 125(s + 0.2);
where the first term is set to zero if the 850 mb Td (°C) is negative; TT is the Total Totals Index (if TT < 49, the term is set to zero); f is the wind speed in knots; and s = sin (500 mb wind direction - 850 mb wind direction). The last term is set to zero if any of the following is not met:

1. the 850 mb wind is between 130°-250°;
2. the 500 mb wind is between 210°-310°;
3. (the 500 mb wind direction - the 850 mb wind direction) is greater than zero; or 4) both the wind speeds are greater than or equal to 15 kts.

SWEAT values +250 indicate a potential for strong convection.
SWEAT values +300 indicate the threshold for severe thunderstorms.
SWEAT values +400 indicate the threshold for tornadoes.