IMPACT OF THE SCANDINAVIAN MOUNTAINS ON A HIGH-IMPACT CYCLONE IN AUGUST 2003

In August 2003, Central Norway was hit by extreme precipitation. The cyclone that caused the precipitation has been simulated with a high-resolution model, and several sensitivity studies have been carried out. The simulations reveal that the release of latent heat had a major impact on the development of the cyclone. The cyclone occurred during a period of anomalously high sea surface temperatures (SST). Numerical tests show however that the development of the cyclone and the extreme precipitation are fairly insensitive to the SST. Removing the orography of Scandinavia leads to a deformation of the cyclone; when the orography is present a lee trough is formed over SE-Norway and the pressure gradient to the west of the low as it moves over SE-Norway is stronger than in the run with no mountains. The results will be helpful in analysing similar events in coarse-resolution climate simulations, where the mountains are poorly resolved