1. Trends and Variability of Storminess in the NE Atlantic-European region, 1874-2007 Xiaolan L. Wang, Francis, W. Zwiers, Val R. Swail, and Yang Feng Climate Research Division, Environment Canada

2. Pressure triangles in the NE Atlantic-European region (similar to Alexandersson et al. 2000)

3. Area averages - 10 triangles in the region (similar to Alexandersson et al. 2000) Annual percentiles However, there are significant seasonality and regional differences 11-point Gaussian low-pass filtered curves

4. a. Winter (DJF) 99 th percentiles NTB APVD JTB JST VST VTAP BBV DAPV APTB BAPV BTB

5. b. Summer (JJA) 99 th percentiles NTB APVD JTB JST VST VTAP BBV DAPV APTB BAPV BTB

6. Winter (DJF) seasonal percentiles Summer (JJA) seasonal percentiles Area averages - four triangles over the North Sea

7. c. Spring (MAM) 99 th percentiles NTB APVD JTB JST VST VTAP BBV DAPV APTB BAPV BTB

8. NTB d. Autumn (SON) 99 th percentiles NTB APVD JTB JST VST VTAP BBV DAPV APTB BAPV BTB

9. Acknowledgements. The authors wish to thank Dr. Gil Compo and other members of the ISPD Working Group for providing us the in-situ pressure data analyzed in this study.