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Atmospheric Rivers and Precipitation Accumulation

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Atmospheric Rivers and Precipitation Accumulation 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 (oC) Recent Evolution The latest weekly SST departures are: Niño 4 1.1ºC Niño 3.4 2.4ºC Niño 3 2.8ºC Niño 1+2 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 Historical Strong El Nino Outcomes 48.4” DJFM 8SI 20.2” 35.7” 171% April SWE 83% 148% 25.3°F Winter Sierra 22.5°F 23.5°F Tmin avg 9.13” San Diego DJFM 8.92” 7.18” 59.6” 24.0” 53.5” 227% 60% 158% 26.4°F 27.6°F 26.6°F 2015 24.1” 5% 13.98” 11.27” 13.89” 32.1°F From NWS Sacramento 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 60 50 2012 40 2014 2015? Record warmth 30 Annual Precipitation (inches) Precipitation Annual 20 10 2013 Record dry 0 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 6 25 20 2015? 15 Record warmth 2012 10 2014 5 2013 0 57 58 59 60 61 62 63 64 65 1895-2000 2001-2014 PORAverage Source: NOAA Climate Division 2 Calendar Year Data Sierra Snowpack vs Winter Temperature 1950-2015 250 Sierra Region 200 150 100 50 2012 2013 2014 April 1 Snowpack Percent of of April 1 Average Percent Snowpack 2015 0 9 Years Below 50% From California Cooperative Snow Surveys Snow Cooperative California From 20 22 24 26 28 30 32 34 Sierra Winter (DJF) Average Minimum Temperature (degrees Fahrenheit) Temperature Data from California Climate Tracker, WRCC Northern Sierra 8 Station Index Lower elevation mountains Average of: Annual Average: 50 inches Mt. Shasta City Quincy Maximum Year (1983): 88.5 inches Shasta Dam Sierraville RS Minimum Year (1924): 17.1 inches Mineral Pacific House Period of Record 1921- Present Brush Creek RS Blue Canyon Pineapple Express Source: CNAP RISA Atmospheric Rivers and Precipitation Accumulation 1/3 of northern 16.8” Sierra snowpack 404 Days fell in 7 days 1/3 of WY total fell in 7 days 8.4“ in 14 days Satellite Observation of Water Vapor Atmospheric River North America Angle of Impact Important Flux Magnitude and Duration are Key The Storm of 4-5 Jan 2008 Note that major impacts were focused >500 miles south of the Low pressure center in this storm. This differs significantly from L hurricanes, but the impacts are enormous and spread over a large area 6-10 ft snow 32 ft waves Many major impacts are 7-13 in associated with the landfall of rain the “atmospheric river” element of the storm. Atmospheric river GOES IR image of major West Coast storm • Time = 0030 UTC 5 January 2008 • Low pressure center is off WA coast Slide from M. Ralph Key Phenomena Affecting California Water Supply/Flooding: Polar Processes Flooding & Cyclogensis water supply Storm Track changes L MJO/Tropical Convection ENSO Easterly Wave 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: [email protected] .
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