500 hPa height perturbation relative to zonal mean (solid contours every 30 m; zero contour omitted; red positive; blue negative), ageostrophic geopotential flux (arrows in m3 s-3), and ageostrophic geopotential flux divergence (shaded in x10-2 m2 s-3).
NCEP GFS analyses and forecasts on 1x1 latitude-longitude grid are smoothed with a 9-point local smoother run 30 times.