tc2m = temperature at 2m above ground [°C]
urgd10m, vgrd10m = u/v component of wind 10m above ground

'define windchill2m = 13.12+(0.6215*tc2m)-(11.37*pow((mag(ugrd10m,vgrd10m)*3.6),0.16))
                      +(0.3965*tc2m*pow((mag(ugrd10m,vgrd10m)*3.6),0.16))'