Three cases are examined of troughs developing in the summer of 1953-4. The first represents a rapid development and eastward movement characteristic of early and late summer; the second a more persistent type occurring frequently in midsummer; and the third a variation of the second. The cases considered are typical of troughs which present problems of prognosis, but they do not cover the whole field. Their significance in relation to forecasts of temperature in the Perth region is brought out, and the article draws attention to some criteria which the author has found useful in indicating when the trough would commence a steady eastward movement.
D. Gaffney (Wed,) studied this question.