The sudden breakdown of an unusually strong cyclone in the stratosphere during winter 1988/89

In February 1989, a dramatic major warming occurred in the stratosphere of the northern hemisphere after an unusually cold January. the stratospheric westerly vortex was split when an anticyclone developed over Europe, apparently in response to cyclogenesis upstream in the troposphere. At the peak of the warming, the circulation resembled that of the warming of February 1979, save for a rotation of flow patterns. Very low temperatures in the lower stratosphere before the warming indicate that polar stratospheric clouds were present, so that heterogeneous chemical reactions with the potential for ozone destruction may have taken place.