We investigated the relationships between the maintenance and predictability variations of blocking characterized by a pronounced meandering of the midlatitude westerly jet stream and an upstream storm track which is a frequent region of travelling highs and lows, via both diagnostic study of reanalysis data and weather forecast experiments. Through case study, we found that the maintenance of blocking is supported by the interaction with the storm track and predictability variation of the block maintenance is related to strength (efficiency) of the interaction.
We also investigated how error in the initial values for weather-forecast experiments existing at an extratropical region propagates by using the reanalysis data and a weather forecast model same as the above study. Results showed that the error propagate eastward from initial positions via the westerly jet stream in the upper troposphere.