From a study of a series of specially analysed charts it is concluded that the standard vector deviation. of the errors in synoptic analysis of upper winds is generally less than 10 knots at the 700 mb level but may be as high as 20 knots at the 300 and 200 mb levels, From a study of the accuracy of 24 hour forecasts it is concluded that the standard vector deviations of the errors in upper wind forecasts are of magnitude comparable with the standard vector deviation of the interdiurnal change.
A. Garriock (Sun,) studied this question.