1. Precipitation Intensity Climate Impacts Group & Department of Atmospheric Sciences University of Washington Eric Salathé

2. Climate Change: North America Annual SummerWinter

3. Climate Change: Pacific Northwest Precipitation Precipitation Change (%) Change in U.S. PNW precipitation by month from 1990s to future simulated by 20 climate models

4. Consensus of current Global Climate Models:  Intensification of Mid-latitude storms  Less frequent storms  Northward shift in storm track Changes in Pacific Storm Track

5. Shift in Pacific Storm Track J Yin, Geophys Res Lett, 2005 S Pole N Pole EQ Temperature Change 1980-2000 to 2080-2100 Change in Storm Growth

6. Shift in Pacific Storm Track Salath é, Geophys Res Lett, 2006 Observed (NCEP-NCAR Reanalysis) 20th Century Model Composite 21st Century Model Composite 1950-2000 to 2050-2100 Nov-Dec-Jan

7. Shift in Aleutian Low Salath é, Geophys Res Lett, 2006 Observed 20th Century Model Composite 1950-2000 to 2050-2100 Nov-Dec-Jan

8. Movement of Jetstream 1950s

9. Movement of Jetstream 1960s

10. Movement of Jetstream 1970s

11. Movement of Jetstream 1980s

12. Movement of Jetstream 1990s

13. Movement of Jetstream 1950s

14. Are extreme rain events becoming more frequent? Valérie Dulière, Philip Mote, Eric Salathé, Josiah Mault and Marketa McGuire Elsner (Climate Impacts Group, University of Washington) 2008 Pacific Northwest Weather Workshop Source : THE OREGONIAN/Bruce Ely

15. The Chehalis River flooding

16. The Centralia station

17. Distribution function of daily precipitations from 1948 to 2006 10 cm5 cm

18. The Centralia station Distribution function of daily precipitations from 1948 to 2006 (Zoom) 10 cm5 cm

19. 1990 2001 2006 1996 1986 1951, 1981 1986 1994, 1986 The Centralia station Distribution function of daily precipitations from 1948 to 2006 (Zoom) 10 cm5 cm

20. 1990 2001 2006 1996 1986 1951, 1981 1986 1994, 1986 Since 1948, 80% of the 20 greatest extreme daily rain events occurred after 1985! The Centralia station Distribution function of daily precipitations from 1948 to 2006 (Zoom) 10 cm5 cm

21. Return period of annual maximum daily precipitation --1948-1976 --1977-2006 The Centralia station 2.5 yr 3.3 in

22. Source : THE OREGONIAN/Bruce Ely The Past 50 Years

23. The Cooperative Observer Program network

24. Return period of annual maximum daily precipitation --1948-1976 --1977-2006 The Centralia station 10-year Return } Percent Change

25. 12345678910 Percentages of change in the annual maximum daily precipitation with a 10 years return period for each station

26. 12 3456 7 89 10

27. What Do Climate Models Project for the Future? Source : THE OREGONIAN/Bruce Ely

28. Projected Future Changes from Climate Models (2046-2065 versus 1981-2000)

29. IPSL SRES A1BSRES B1 Percentages of change in the annual maximum daily precipitation with a 10 years return period for each grid cell between 1981-2000 and 2046-2065. ECHAM5 CCSM3 Projected Future Changes from Climate Models (2046-2065 versus 1981-2000)

30. IPSL SRES A1BSRES B1 Percentages of change in the annual maximum daily precipitation with a 10 years return period for each grid cell between 1981-2000 and 2046-2065. +18.8%+11.8% ECHAM5 CCSM3 Projected Future Changes from Climate Models (2046-2065 versus 1981-2000)

31. IPSL ECHAM5 SRES A1BSRES B1 Percentages of change in the annual maximum daily precipitation with a 10 years return period for each grid cell between 1981-2000 and 2046-2065. +18.8% +11.4% +11.8% +10.6% CCSM3 Projected Future Changes from Climate Models (2046-2065 versus 1981-2000)

32. IPSL ECHAM5 SRES A1BSRES B1 CCSM3 Percentages of change in the annual maximum daily precipitation with a 10 years return period for each grid cell between 1981-2000 and 2046-2065. +12.2% +18.8% +11.4% +10.8% +11.8% +10.6% Projected Future Changes from Climate Models (2046-2065 versus 1981-2000)

33. Number of days per year Number of days per year with P > 0.4 inches Projected Future Changes from Climate Models (2046-2065 versus 1981-2000)

34. Number of days per year Number of days per year with P > 0.4 inches P > 1.6 inches

35. Number of days per year with P > 0.4 inches P > 1.6 inches P > 2.8 inches Number of days per year Projected Future Changes from Climate Models (2046-2065 versus 1981-2000)

36. GOING TO THE EXTREMES  GOING TO THE EXTREMES AN INTERCOMPARISON OF MODEL-SIMULATED HISTORICAL AND FUTURE CHANGES IN EXTREME EVENTS CLAUDIA TEBALDI, KATHARINE HAYHOE, JULIE M. ARBLASTER and GERALD A. MEEHL, Climatic Change (2006) 79: 185-211  9 Global Model Simulations for IPCC  1. Number of days with precipitation greater than 10 mm (precip > 10).  2. Maximum number of consecutive dry days (dry days).  3. Maximum 5-day precipitation total (5 day precip).  4. Simple daily intensity index, defined as the annual total precipitation divided by the number of wet days (precip intensity).  5. Fraction of total precipitation due to events exceeding the 95th percentile of the climatological distribution for wet day amounts ( precip > 95th).

37. Going to Extremes

39. Mesoscale Effects  Global models do not resolve fine-scale processes such as topographic precipitation  Downscaling methods are used to account for regional effects  Statistical downscaling uses observed relationship between large-scale and fine-scale patterns to extrapolate to climate model results  Regional climate model simulates fine-scale physical processes

40. Change in Orographic Enhancement Salath é, Geophys Res Lett, 2006 Downscaling without wind effect 1990-2000 to 2045-2055 Sept-Oct-Nov Downscaling with wind effect

41. Mesoscale Climate Model  Based on Regional Weather Model (MM5, WRF)  Nested grids 135-45-15 km  Advanced land-surface model (NOAH) with interactive deep soil temperature  Global Climate Model used as Input (boundary conditions)

42. Autumn Precipitation Changes mm per day Change in Autumn precipitation rate from 1990s to 2050s as simulated in regional climate model Winds Shift to Onshore Rain increases along mountain ridge Change in Orographic Enhancement

43. MM5 vs Statistical Downscaling Statistical Downscaling P onlyP & Wind MM5 Change in November Precip (mm/day) 1990s to 2050s

44. Conclusions : -This is the beginning of our work. - According to the observations from the COOP network, extreme rain events have globally increased in frequency and intensity between 1948- 1976 and 1977-2006 over the Washington state. - According to global climate models (IPSL, ECHAM5 and CCSM3), extreme rain events will in average be more intense and more frequent in 2046-2065 than now, over the PNW region. Coming next : Analysis of output from regional climate models. Source : http://www.earthcam.com/