12 



Figure 2. Twelve-hour 500 mb forecasts for I5OO GMT 10 February 1957. 

 (a) Barotropic. Solid lines are the predicted contours; dashed lines 

 are the observed contours, (b) "No Flux." (c) "Complete." Contours 

 are drawn for an interval of 200 geopotential feet. See text page 10. 



