2.2 Future Changes in Severe Thunderstorm Environments over Europe

Monday, 7 November 2016: 10:45 AM
Pavilion Ballroom (Hilton Portland )
Tomas Pucik, European Severe Storms Laboratory, Wessling, Germany; and P. Groenemeijer, L. Tijssen, and A. T. Westermayer

Changes in conditions that support severe convective storms during the 21st century were studied using an ensemble of 14 regional EURO-CORDEX climate models at 0.44° resolution. EURO-CORDEX produces improved regional climate change projections for Europe. The model ensemble represents a spectrum of local climate models run by different climate research institutes across Europe using boundary conditions provided by a range of global climate models.

The present environment of (severe) thunderstorms is characterized by a historical control period spanning the years 1971 – 2000. Future changes were addressed by comparing two 30-year periods, 2021 – 2050 and 2071 – 2100 to the historical period.  rcp4.5 and rcp8.5 scenarios were chosen to represent the scenarios of moderate climate change risk mitigation and no climate change risk mitigation.

 The ensemble simulates an increase of latent instability over all of Europe until the end of the century. The increase is the largest, and most consistent among the ensemble models, over the south-central and north-eastern parts of the continent in the rcp8.5 scenario in the 2071-2100 period. This increase is caused by an increase of absolute moisture in the lower troposphere, while mid-tropospheric lapse rates do not change or decrease only slightly. This increase in instability suggests that environments supportive of thunderstorms will become more frequent. In southern Europe, however, the number of precipitation events in the presence of instability was found to decrease.

Deep-layer vertical wind shear will almost nowhere change significantly. This is also true for the wind shear in unstable situations. An increase in the number of situations featuring pronounced instability and strong vertical wind shear is predicted, which indicates an increase of number of environments conducive to severe thunderstorms. The results will be discussed in the context of expected changes in the number of severe thunderstorms. A further discussion point will be the uncertainty of the predictions due to diverging model predictions and the limitations of the used resolution, especially with respect to the very complex terrain and coastline patterns of Europe.

- Indicates paper has been withdrawn from meeting
- Indicates an Award Winner