Caption: +500 hPa geopotential height (solid contours every 6 dam). +500 hPa quasi-geostrophic potential vorticity (green contours every 0.25 PVU; dashed<0). +Total RHS of QGPV form of QG height tendency equation [shaded according to the colorbar (10-13 s-3)]. Cold (warm) colors denote regions of forcing for 500 hPa geopotential height falls (rises). +Image was generated from smoothed 1.0x1.0o NCEP-GFS data.