Severe Thunderstorm Evaluation and Predictability in Climate Models

In Europe, thunderstorms are increasingly recognised as an important hazard to life and property. According to the Munich Re Group, a yearly total damage of about € 5 billion (Munich Re Group, 2006) is inflicted by thunderstorm-related severe weather events (hail, flash floods, straight-line winds, tornadoes, and lightning) in Europe. Yet, relatively little is known about what effects climate change has on the frequency and intensity of these localised and short lived hazards.
The spatial and temporal resolution of global as well as regional models is insufficient to simulate thunderstorms and their attendant hazardous phenomena.  Yet  these models do contain information related to the occurrence of these events.  Within STEPCLIM a method is developed that will allow climate models to be used for the prediction of the frequency and intensity of hail, tornadoes, severe wind gusts and extreme rainfall in the future.
The development of this method requires that quality-controlled datasets of severe weather occurrence be available. To that aim, STEPCLIM will first evaluate the quality of two of such datasets, to wit the  European Severe Weather Database (ESWD)  and Storm Data. Subsequently, the dataset managed by ESSL (ESWD) will be further optimized for use in further analyses within the project.
Secondly, a first range of metrics will be developed by relating severe weather observations with reanalysis datasets, i.e. data that represents the past weather.  Third, these metrics will be calibrated by applying them to both global and regional datasets of the past climate (so-called hindcasts). This procedure will be repeated in the final phase of the project, using the improved ESWD dataset and the improved MiKlip system for decadal climate prediction.
Finally, the predictability of thunderstorm-related weather hazards using the MiKlip system will be assessed. After a final calibration of the metrics, these, and the software to compute them, will be integrated into the MiKlip system.

Goals

• To develop metrics for assessment of thunderstorm hazards using storm databases and reanalysis data
• To apply these metrics to MiKlip climate simulations
• To assess projected changes in the thunderstorm climate and its predictability
• To establish methods to use observational storm data taking into account the inherent limitations of such data sets
• To expand the ESWD dataset to mitigate inhomogenity shortcomings
• To develop a software tool to perform validation of thunderstorm projections of MiKlip system

STEPCLIM will be conducted by the European Severe Storms Laboratory seated in Wessling, Germany.