Stratospheric harbingers of anomalous weather regimes

Observations show that large variations in the strength of the stratospheri c circulation, appearing first above similar to 50 kilometers, descend to t he lowermost stratosphere and are followed by anomalous tropospheric weathe r regimes. During the 60 days after the onset of these events, average surf ace pressure maps resemble closely the Arctic Oscillation pattern. These st ratospheric events also precede shifts in the probability distributions of extreme values of the Arctic and North Atlantic Oscillations, the location of storm tracks, and the local likelihood of mid-latitude storms. Our obser vations suggest that these stratospheric harbingers may be used as a predic tor of tropospheric weather regimes.