Three case studies are used to evaluate the interactions between individual synoptic events and the sea ice cover of parts of the western Arctic in October 1976. Changes in both ice extent and concentration are assessed quantitatively by using 2-day averaged passive microwave data from the Nimbus 5 ESMR (electrically scanning microwavve radiometer). These are related to daily 850-mbar resultant wind patterns for the periods considdered. Strong anticyclonic conditions are associated with relatively static surface brightness temperatures (TB) and hence with generally stable ice conditions. Conversely, a quasi-stationary cyclonic system produces marked TB variations involving rapid changes in ice edge position and ice concentrations. Transient atmospheric (temperature, moisture) fluctuations, associated with the passage of synoptic systems, are found not to be negligible in the interpretation of microwave sea ice TB signatures on short time scales.