Weather Regimes and Low-level Temperature-fields

In the present paper we discuss weather regimes in the Northern Hemisphere, identified by means of the probability density distribution of an indicator of the planetary scale 850 mb eddy field during winter. We found that inter-regimes differences have behaviour similar to the one shown at the 500 mb geopotential height. We have speculated that at the upper tail of the distribution of the indicator there may be an additional mode representing a double global blocking flow. For this regime we found that significant features are present also in a sector encompassing the Mediterranean basin. Few speculations about the feasibility of limited-area forecast during inter-regime transition are offered.