1. SOMs Work Analysis Region Top Widespread Events Location of Extreme Precipitation

2. DJF Master SOM Produced with ERA-Interim + SN WRF-50.hPa MSLP anomalies (1989- 2007) Widespread extreme days (99 th percentile, w/ at least 25 grid points) from WRF mapped onto Master SOM

3. 99 th Percentile

5. Top 10 DJF Composite

7. Top 5 DJF Composite

9. Top DJF Event

11. Extreme Node Selection In some analysis regions, nodes are being accessed that don’t show favorable circulation for widespread precip. extremes Some regions may need a smaller Master SOM, as strong features far from region may confound node selection

12. Native WRF output vs. NCDC- based WRF output

13. Comparing Node Frequencies 1.Extracted WRF widespread extreme events from N. American analysis region 2.Extracted NCDC station extremes from same regions 3.Extracted WRF output from grid points closest to NCDC station 4.Compared node frequencies from the three sources

14. Native WRF: L-H-L signal seems to be the dominant circulation feature. Highly accessed nodes on the periphery of SOM space, in general.

15. NCDC observations don't really show the L-H-L pattern that we find in the model output; we find a strong Aleutian low and a region of relaxed high pressure over the eastern part of domain.

16. Similar L-H-L as found in native WRF. Highest frequency node, however, shows a low pressure feature over Gulf of Alaska, with H pressure over the Bering Strait.