1. NOAA’s California-Nevada Applications Program

2. Dettinger, SFEWS, 2005 PROJECTED CHANGES IN ANNUAL TEMPERATURES, NORTHERN SIERRA NEVADA PROJECTED TEMPERATURE CHANGES -4F 20 of 23 in this range 0F +4F +8F 12F

3. All DrierAll Wetter Among 12 projections with high-CO2 emissions, how many models yield increasing (decreasing) precipitation? PROJECTED PRECIPITATION CHANGES Northern California still on the edge between more-or- less precipitation. Percentage Change from Historical Normals

4. PROJECTED SNOW CHANGES Courtesy of David Pierce, SIO End snow szns (9 CMIP5 RCP4.5 GCMs BCCA downscaled, VIC snow simulated) Rain vs Snow More change NO change Start snow szns Dettinger & Culbertson, SFEWS 2008 More rain vs snow Shorter snow-cover seasons Earlier snowmelt & runoff

5. Cayan et al., SWCA, 2013 16 models, A2 emissions Northern Sierra Nevada Median of A2 emissions Median of B1 emissions Center of sliding 50-yr window Percentage of historical 50-yr flood Das et al., ClimChg, 2012; JH, in rev PROJECTED STREAMFLOW CHANGES Distributions of 50-yr flood changes

6. PROJECTIONS of MONSOONS/FIRE-WEATHER June-September, 2041-69 vs 1971-99 PrecipitationTemperature June-October, 2080-99 vs 1980-99 Moist Static Energy Reductions in summer precipitation? (Mearns et al. 2009) Later monsoon arrivals & withdrawals (Cook & Seager, 2013) More stable atmosphere, less thunderstorming (Cook & Seager, 2013)

7. 50-yr Floods PROJECTIONS of LARGEST WINTER STORMS (Atmospheric rivers, or pineapple expresses) Update to Dettinger, JAWRA, 2011

8. “ARkStorm” Consequences at Lake Tahoe

10. FROM CLIMATE/HYDRO MODELS & OTHER CONSIDERATIONS, WE PROJECT: Warming by +3 to +6ºC across Sierra, likely more so at higher altitudes Much of Sierra in range for modest, wetter-or-drier trends Monsoons may be delayed/reduced Extreme weather/floods gets more extreme More rain, less snow Less snowpack Increased winter flood risks but longer low flows Less overall streamflow (think -5 to -15%) Changes in aquifer recharge Longer growing seasons More, more severe heat waves Fewer (but deeper?) cold snaps Increased wildfires Favors many invasive species

11. 11 For much more info on these & other topics, see the new 2013 Southwest Climate Assessment Report : http://www.swcarr.arizona.edu Contact mddettin@usgs.gov w/questions or for info re: ARkStorm@Tahoemddettin@usgs.gov