upper air ascents made at Shanwell, on the Tay estuary, at 00 and IZ GMT (Fig. 7), were strictly representative of the active part of the cold pool. The ascents showed the low-level inversion typical of the easterly situation, but the greatest change associated with the passage of the cold pool was not in the stability, but just a marked increase in humidity over a considerable depth indicating the thickness of cloud.
CONCLUSIOISSThe question to ask in hindsight is whether, knowing that the cold pool had an area of cloud in association with it, one should have forecast its subsequent development, as well as its movement, over Scotland. The satellite pictures indicate that the weather over the rest of the British Isles was similar on both days and thus according to forecast.This case is certainly a striking example of how satellite pictures, taken at intervals of some 24 hours, although greatly aiding analysis of a situation, need not necessarily lead to an accurate forecast -a popular misconception. Moreover, the idea that the surface isobaric chart is all that is necessary for a correct weather forecast also suffers, but comfort must be drawn from the fact that it is not often that a stationary ridge of high pressure produces such a soaking!