National Geographic : 1969 Oct
Sa Warning from the sky: A blanket of snow Slices ominously over the northern Midwest in a picture beamed to earth on March 21 S by weather satellite ESSA 7. The solid white mass behind wispy clouds spreads heaviest in the Dakotas and Minnesota 7(above). Comparison of daily satellite pic tures warned of the melt that unleashed last spring's onslaught. SATELLITEPHOTOGRAPHCOURTESYESSA;KODACHROME© N.G.S. Preflood patrol deploys from a U. S. Army helicopter on a South Dakota plain to measure snow depth and water content. Such surveys by the Weather Bureau, an agency of the Environmental Science Services Administration, gave early warning that record-high river levels were to come. Federal, state, and local governments last winter launched emergency preparations in a mammoth campaign called Operation Foresight. Even local gravediggers cooperated by reporting frost lines, 578 important in predicting how quickly snow melt would run off fields.