A study of non-forecasted cyclogenesis in a polar air mass over the Baltic Sea

Abstract

We present a case study of a developing meso-scale low in a cold air mass where baroclinicity was weak. Both mid-tropospheric vorticity advection and enhanced organized convection over the Baltic Sea seem to have caused the initial development. Later, baroclinic instability took over the dominating role in the development. The low studied exhibited properties of both polar lows and comma clouds. The case was simulated by a high-resolution limited area numerical model, which failed to develop the intense meso-scale part of the surface cyclone, probably because of too coarse a resolution.