Caption: +Dynamic tropopause potential temperature (shaded according to the color bar in K). +Dynamic tropopause wind (standard barbs in knots). +925-850 hPa layer-average relative vorticity (solid contours every 5.0x10-5 s-1 starting at 5.0x10-5 s-1). +Image was generated from 1.0x1.0o NCEP-GFS data, and the dynamic tropopause = -2.0 PVU.