Interannual cycles and trends in Arctic ice cover are dominated by strong regional variability. Arctic sea ice extent exhibited a record minimum within the Arctic Basin during September 1990, dominated by a rapid retreat in the Chukchi, East Siberian, and Laptev Seas. Simulations using a coupled regional model reproduced the enhanced cyclonic activity and enhanced ice melt which led to this large retreat in sea ice cover. Sensitivity experiments showed that accurate initial ice conditions are crucial for a realistic simulation of the ice anomaly, pointing to the need for adequate spin-up in coupled model experiments. It was also found that thermodynamic melt can account for the bulk of the total loss in ice mass over the summer season in 1990, but without dynamics, the spatial patterns characteristic of the ice reductions are not reproduced well. Also, transport of ice was crucial to initiate the formation of the anomaly, even if the formation was delayed until later in the season. The ice-albedo feedback is important in allowing the continued formation of the ice anomaly throughout the summer. Interannual variations in atmospheric circulation that yield regional differences in ice thickness provide a preconditioning that significantly affected development of the ice anomaly. This suggests that circulation modes play an important role in determining ice severity along the Siberian coast. ¿ 2001 American Geophysical Union