Windstorms of 11 April 1944 were associated with the eastward movement of a large pulsation in pressure and strong easterly surface winds. Barograph and wind records from many stations are used to show the hourly movement of this pulsation. Precipitation records from the hydrologic network of recording rain-gages are used to determine the hourly movement of a sequence of four bursts of rainfall associated with thunderstorms, tornadoes and pressure pulsations. The pressure pulsation is shown to be an exceptional case of a phenomenon which is frequently overlooked, and about which as yet our knowledge of the physical processes involved is very incomplete.