El Niño, Climate Change and Water Supply Variability
Talk Overview El Niño and California California Climate Variability and Change Water Management in the Face of Change
California s topography affects our weather and climate and is central to our water resources management
Niño Region SST Departures ( o C) Recent Evolution The latest weekly SST departures are: Niño 4 Niño 3.4 Niño 3 Niño 1+2 1.1ºC 2.4ºC 2.8ºC 2.8ºC http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.shtml
SST Outlook: NCEP CFS.v2 Forecast (PDF corrected) Issued: 2 October 2015 The CFS.v2 ensemble mean (black dashed line) predicts El Niño through MAM 2016. Year DJF JFM FMA MAM AMJ MJJ JJA JAS ASO SON OND NDJ 2015 0.5 0.4 0.5 0.7 0.9 1.0 1.2 1.5 2.0? http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.shtml
From NWS Sacramento Historical Strong El Nino Outcomes 48.4 DJFM 8SI 20.2 35.7 171% April SWE 83% 148% 25.3 F 22.5 F 23.5 F Winter Sierra Tmin avg 9.13 San Diego DJFM 8.92 7.18 59.6 24.0 227% 60% 26.4 F 27.6 F 53.5 158% 26.6 F 2015 24.1 5% 32.1 F 13.98 11.27 13.89
California s precipitation is uniquely variable Std Dev of Annual Precipitation Mean Annual Precipitation Higher values are higher variability Source: Dettinger et al (2011)
Storms and California Water Supply Just a few storms each year are the core of California s water supplies Dettinger et al, 2011
Decadal scale precipitation variability tied to Atmospheric River landfall variability Source: Dettinger and Cayan (2014)
NOAA Climate Division 2 Calendar Year Data 1895-2014 80 70 2 Annual Precipitation (inches) 60 50 40 30 20 2012 2014 Record warmth 2015? 10 0 2013 Record dry 50 51 52 53 54 55 56 57 58 Annual Average Temperature (deg F) 1895-2000 21st Century POR Average Source: NOAA Climate Division 2 Calendar Year Data
NOAA Climate Division 6 Calendar Year Data 1895-2014 40 35 30 25 6 20 15 10 5 2012 2013 Record warmth 2014 2015? 0 57 58 59 60 61 62 63 64 65 1895-2000 2001-2014 PORAverage Source: NOAA Climate Division 2 Calendar Year Data
Temperature Data from California Climate Tracker, WRCC April 1 Snowpack Percent of Average From California Cooperative Snow Surveys Sierra Snowpack vs Winter Temperature 250 200 150 100 50 0 9 Years Below 50% 1950-2015 2013 2012 2014 Sierra Region 2015 20 22 24 26 28 30 32 34 Sierra Winter (DJF) Average Minimum Temperature (degrees Fahrenheit)
Northern Sierra 8 Station Index Lower elevation mountains Annual Average: 50 inches Maximum Year (1983): 88.5 inches Minimum Year (1924): 17.1 inches Period of Record 1921- Present Pineapple Express Source: CNAP RISA Average of: Mt. Shasta City Shasta Dam Mineral Brush Creek RS Quincy Sierraville RS Pacific House Blue Canyon
Atmospheric Rivers and Precipitation Accumulation 1/3 of northern Sierra snowpack fell in 7 days 16.8 404 Days 1/3 of WY total fell in 7 days 8.4 in 14 days
Satellite Observation of Water Vapor Atmospheric River North America
Flux Magnitude and Duration are Key Angle of Impact Important
The Storm of 4-5 Jan 2008 Note that major impacts were focused >500 miles south of the Low pressure center in this storm. L 32 ft waves Atmospheric river GOES IR image of major West Coast storm Time = 0030 UTC 5 January 2008 Low pressure center is off WA coast 6-10 ft snow 7-13 in rain This differs significantly from hurricanes, but the impacts are enormous and spread over a large area Many major impacts are associated with the landfall of the atmospheric river element of the storm. Slide from M. Ralph
Key Phenomena Affecting California Water Supply/Flooding: Polar Processes Storm Track changes Cyclogensis L Flooding & water supply MJO/Tropical Convection Easterly Wave ENSO The size, number, and strength of atmospheric river events (ARs) result from the alignment of key processes
ARs, California Water and Change Flux, Duration, Direction, and Spatial Extent of Storm play roles in how much water goes where Antecedent watershed conditions important to runoff response and impacts Number, timing, and character of storms important to seasonal accumulation of precipitation and snowpack Ocean, Atmosphere, and Land Surface Processes play important roles and will evolve as climate changes
Final Thoughts A warmer world will likely involve more variability and stronger pulses of water input to California (floods within droughts possible) The ability to manage water will increasingly rely on ability to forecast events and manage projects and systems nimbly in real-time Seasonal forecasting offers opportunity to set expectations for water management and possibly more as warming continues
Questions? Email: Michael.L.Anderson@water.ca.gov