A Vision for Future Observations for Western U.S. Extreme Precipitation and Flooding

A Vision for Future Observations for Western U.S. Extreme Precipitation and Flooding Dr. Marty Ralph Center for Western Weather and Water Extremes (CW3E) UCSD/Scripps Institution of Oceanography 24 June 2014 Workshop on Hydroclimate Monitoring and Measurement Needs Western States Water Council San Diego, California 1

California has deployed key land-based sensors GPS receiver for integrated water vapor An Atmospheric River-focused long-term observing network is being installed in CA as part of a 5-year project between CA Dept. of Water Resources (DWR), NOAA and Scripps Inst. Of Oceanography - Installed 2008-2014 - >100 field sites ¼-scale 449-MHz wind profiler with RASS FM-CW snow-level radar Soil Moisture and Temperature Probes White et al. 2013, J.Tech. 2

Core Observing System Concepts The lower 5,000 feet of the atmosphere is where much of the action takes place, but is poorly observed Mountains complicate use of radars in the West, requiring special attention to siting, scanning and profiles Many important storms initially take form over the Pacific Ocean, where satellites help, but major gaps remain Soil and snowpack conditions in mountains impact floods 3

Background The WSWC passed a Resolution in 2011 that supports development of an improved observing system for Western extreme precipitation events, to aid in monitoring, prediction, and climate trend analysis associated with extreme weather events NOAA s Hydrometeorology Testbed (HMT) and other efforts have improved understanding of how extreme events occur, have identified gaps and prototyped solutions, which are the foundation of this Vision The Western Obs Vision was recently published in the Journal of Contemporary Water Research and Education (April 2014). 4

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Key reports, papers and other sources used to inform the development of this Vision Source Description and references NRC reports Flooding in Complex Terrain; Network of Networks; GPM Satellite system Needs assessments Workshop on non-stationarity (2010), USBR Science and Technology Program (2011), NOAA s Water Cycle Science Challenge Workshop (2012), USWRP Workshop (2005) IWRSS USACE, USGS, NOAA formal agreement and coordination; National Water Center NOAA/HMT 10-year effort on extreme precipitation causes and predictions (Ralph et al. 2005; 2013a) Atmospheric rivers Understanding of the joint roles of atmospheric rivers in extreme events and water supplies in the west (Dettinger et al. 2011) ARkStorm USGS-led emergency preparedness exercise in California focused on atmospheric rivers NOAA/RISA Regional Integrated Science and Assessment (RISA) studies on climate change State Climatologists Regional expertise and deep experience in states needs for climate information Unmanned Aircraft NOAA UAS Program observing system gap analysis for atmospheric rivers over Pacific NOAA Radars Cross-NOAA Radar planning team reports NOAA Science Plans NOAA held interagency workshops on water cycle and climate science that produced detailed recommendations for future science directions nationally (NOAA 2012a, 2012b) 6

Analysis from COOP daily precipitation observations. -Each site uses at least 30 years of data -The top 10 daily precip dates are found -The season for which most of these top-10 dates occurred at that site is color coded. Ralph et al. 2014 (JCWRE)

Schematic illustration of regional variations in the primary weather phenomena that lead to extreme precipitation, flooding and contribute to water supply in the Western U.S. (Ralph et al. 2014) Atmospheric Rivers (fall and winter) Great Plains Deep Convection (spring and summer) Front Range Upslope (rain/snow) Key Weather Southwest Monsoon (summer & fall) Phenomena

A Major Result from 10-years of Research Atmospheric rivers what they are, how they work, and their crucial role in both water supply and flooding across much of the U.S. West Coast Figure from an article in Scientific American by Dettinger and Ingram (January 2013)

Atmospheric rivers: Two recent examples that produced extreme rainfall and flooding These color images represent satellite observations of atmospheric water vapor over the oceans. Warm colors = moist air Cool colors = dry air ARs can be detected with these data due to their distinctive spatial pattern. In the top panel, the AR hit central California and produced 18 inches of rain in 24 hours. From Ralph et al. 2011, Mon. Wea. Rev. In the bottom panel, the AR hit the Pacific Northwest and stalled, creating over 25 inches of rain in 3 days. 10

Overview of Scientific Findings from a Decade of Research $50 M invested over 10 years (Federal, State, Local) Table 1. Overview of findings from 10 years of atmospheric river research ARs can Quantitative results Formal reference Cause heavy rain 90% of California s heaviest 1-3 day rain events are from ARs Ralph et al. 2010 Fill reservoirs 40-50% of northern California rain and snow Dettinger et al. 2011 Bust droughts 40% of droughts in northern California ended with an AR Dettinger 2013 Help fish 77% of Yolo Bypass inundations of fisheries/eco. significance Florsheim & Dett.2013 Cause floods 100% for key coastal watersheds (and many in Central Valley) Ralph et al. 2006 Break levees 81% of Central Valley levee breaks were AR related Florsheim & Dett.2013 Catastrophes ARkStorm flood scenario found >$500 Billion impact in CA Porter et al. 2011 Can be monitored Simple & complex tools can help, e.g., radar, aircraft, satellite White et al. 2013 Partly predictable Can be seen >5 days ahead; landfall position error is large Wick et al. 2013 Partly predictable Of 16 AR storms that caused 5 in of rain, 2 were predicted Ralph et al. 2010

Droughts, on average, end with a bang (and begin with a whimper) all over the U.S. Atmospheric rivers provide the bang in a large fraction of the west coast drought breaks, especially in winters 1895-2010 Dettinger, Michael D., 2013: Atmospheric Rivers as Drought Busters on the U.S. West Coast. J. Hydrometeor, 14, 1721 1732.

Orographic controlling layer for upslope flow: 0.75 1.25 km MSL (Neiman et al. 2002) Methodology for AR duration data analysis: 13 Nov. 2004 8 Aug 2010 ARO 915 MHz wind profiler GPS receiver BBY 915 MHz wind profiler: 27 Dec 2005 Russian River flooding: Feb. 2004 photo courtesy of David Kingsmill

Altitude MSL (km) Atmospheric River Observatory Plan view Rain shadow GPS satellite 3 2 Wind profiler beam with 100-m vertical resolution Snow level Wind direction in AR S-PROF data up to 10 km MSL Mountains ARO Orographic cloud and precipitation 1 0 Atmospheric River Ocean Controlling layer (upslope winds) Surface friction and barrier jet S-PROF precipitation profiler; surface met; disdrometer Rain shadow GPS-met receiver Wind profiler (915 or 449 MHz) 10-m surface meteorology tower 0-50 km between wind profiler/gps-met site and S-PROF precipitation profiler 14

ATMOSPHERIC FORCING Example: Case 26 From: To: 12/26/05 08z 12/30/05 08z Defining an AR event using three thresholds: (1) The IWV has to meet or exceed 2 cm (as in Ralph et al. 2004 and subsequent studies). (2) The upslope IWV flux (Neiman et al. 2009) has to meet or exceed 15 cm m s -1. (3) Both variables had to simultaneously meet or exceed those thresholds for at least 8 consecutive hours. The ending time occurs when either IWV or upslope flux falls below its respective threshold. Each case was then uniquely defined by a 96 h time interval with the 24th hour representing the start of the period for which IWV 2 cm and IWV flux 15 cm m s -1 for at least 8 h. 96 hours At least 8 hours

Storm-total rainfall at CZD (mm) 91 AR events observed over 6 years Storm-total upslope water vapor flux at BBY (cm m/s) From Ralph et al. 2013, J. Hydrometeorology

Storm-total runoff on Austin Ck (millions of m 3 ) Storm-total rainfall at CZD (mm) 91 AR events observed over 6 years Storm-total upslope water vapor flux at BBY (cm m/s) Storm-total upslope water vapor flux at BBY (cm m/s)

The Sierra Barrier Jet is key to regional precipitation Neiman, Hughes, Moore, Ralph, and Sukovich (MWR 2013)

Seasonality of Annual Peak Streamflow Seasonality of annual peak daily stream flows highlighting the preponderance of ARdominated regions (blue dots) and Spring-melt dominated regions (red dots in mountains) Spring-Summer snowmelt Atmospheric rivers Fall-Winter 19

Existing SNOTEL sites color coded to their altitude range. Red ovals highlight regions where a subset of the existing SNOTEL sites would have additional sensors emplaced to support better spring snow melt monitoring and prediction, or where new sites would be needed to broaden the altitude range of coverage. 20

Schematic strawman network of new sensors to improve monitoring, prediction and climate trend detection for hydrometeorological conditions that create extreme precipitation & flooding. 21

Validation of AR Forecasts - Approach Automated Atmospheric River Detection Tool (ARDT) applied to evaluate ability of operational NWP models to predict AR events AR features in model fields compared with satellite observations from SSMIS 5 models tested: NCEP, ECMWF, UKMO, JMA, & CMC Evaluated at lead times to 10 days 3 cool seasons in NE Pacific from 2008-9 to 2010-11 Compared frequency of occurrence, width, IWV content, and landfall location NCEP Satellite Observations January 7, 2009 1-Day Fcst 7-Day Fcst Evaluation of Atmospheric River Forecasts in Operational Ensemble Forecast Systems UKMO G. A. Wick, P. J. Neiman, F. M. Ralph, & T. M. Hamill NOAA ESRL/PSD, 2013

AR Landfall Position Forecast Errors While overall occurrence well forecast out to 10 days, landfall is less well predicted and the location is subject to significant errors, especially at longer lead times 500 km forecast error at 5-day lead time RMS Error in Forecast AR Landfall Location Errors in location increase to over 800 km at 10-day lead Errors in 3-5 day forecasts comparable with current hurricane track errors Model resolution a key factor From Wick et al., 2013 (Weather and Forecasting) Models provide useful heads-up for AR impact and IWV content, but location highly uncertain Location uncertainty highlights limitations in ability to predict extreme precipitation and flooding Improvements in predictions clearly desirable

Uncertainty in predicted extreme surface winds found to be associated with an AR Doyle, James D., Clark Amerault, Carolyn A. Reynolds, P. Alex Reinecke, 2014: Initial Condition Sensitivity and Predictability of a Severe Extratropical Cyclone Using a Moist Adjoint. Mon. Wea. Rev., 142, 320 342 Adjoint sensitivity valid at the initial time of 1200 UTC 26 Feb 2010 at 700 mb for water vapor (color coded). Hatched area is water vapor mixing ration >4 g kg -1. The sensitivity maxima are found in the low- and midlevels, oriented in a sloped region along the warm front, and maximized within the warm conveyor belt. The moisture sensitivity indicates that only a relatively small filament of moisture within an atmospheric river present at the initial time was critically important for the development of Xynthia.

CalWater-2* Early Start field campaign 3-25 February 2014 Summary Courtesy of Marty Ralph UCSD/Scripps/Center for Western Weather and Water Extremes This AR increased precipitation-to-date from 16% to 40% of normal in < 4 days in key Northern California watersheds, but runoff was muted due to dry soils. Up to > 12 inches of rain some drought relief Flight area for NOAA s G-IV aircraft on 8 Feb 2014 Goal: developing AR flight method to sample a frontal wave that can cause an AR to stall over one area at landfall (G-IV PI: Chris Fairall NOAA; Mission Scientists: Marty Ralph Scripps, Ryan Spackman STC) Russian River s highest flow in > 1 year Hawaii *CalWater-2 is a 5-year program (from 2015-2019) proposed to focus on West Coast precipitation processes and how a changing climate will affect them. It is led by UCSD/Scripps with partners from DWR, CEC, NOAA, NASA, DOE and others. SSM/I satellite observations of water vapor on 8 Feb 2014 (Courtesy G. Wick, NOAA)

NASA Global Hawk during Test flight for NOAA-led Winter Storm and Pacific Atmospheric River WISPAR dropsonde demonstration project The NOAA Unmanned Aircraft Systems January 2011 (UAS) Program: Status and Activities Gary Wick Robbie Hood, Program Director *Courtesy Dr. Gary Wick (WISPAR Mission Scientist) 26

Benefits Flood damages Western US averages $1.5 B/year Mitigation of 2% of this damage (or $30 M/yr) is likely This does not account for potential water supply benefits 27

Scanning NEXRAD Radar on WA coast $13 M (operating Sept 2011) Cost Comparisons California AR Network >90 sites, 4 sensor types $10 M (underway) Complete Western Network $65 M to develop, acquire and deploy - 325 new surface obs - 25 Atmospheric river observatories - 25 precipitation profiling radars - 24 new C- or X-band scanning radars Offshore Buoy and Aircraft Network $40 M to develop, acquire and deploy - 5 buoy-mounted AROs - 1-2 reconnaissance aircraft Operate, Maintain and Optimize - $35 M/year Combined: $210 M over 6 years 28

Next Step: Implementation Planning Some alternative funding approaches Master Plan with Integrated Federal Appropriation(s) Federal, State, Local (each agency supports what it can) Private sector (users buy data) Some alternative execution strategies Use and better support existing expertise Develop Regional Centers coordinated across agencies A single center coordinates and fills remaining gaps 29

Thank You CW3E web page http://cw3e.ucsd.edu Ralph, F. M., M. Dettinger, A. White, D. Reynolds, D. Cayan, T. Schneider, R. Cifelli, K. Redmond, M. Anderson, F. Gherke, J. Jones, K. Mahoney, L. Johnson, S. Gutman, V. Chandrasekar, J. Lundquist, N.P. Molotch, L. Brekke, R. Pulwarty, J. Horel, L. Schick, A. Edman, P. Mote, J. Abatzoglou, R. Pierce and G. Wick, 2014: A vision for future observations for Western U.S. extreme precipitation and flooding Special Issue of J. Contemporary Water Resources Research and Education, Universities Council for Water Resources, Issue 153, pp. 16-32. 30

Backup slides 31

DWR Program Applications of Atmospheric Rivers Network Data Flood Preparedness and Response Flood Planning Reservoir Coordinated Operations Water Supply Forecasting Monitoring Climate Change Courtesy of Mike Anderson - CA Dept. Water Resources - CA State climatologist

Conceptual Observation Network and Forecast Lead Time of AR Development/Impacts (courtesy of Dave Reynolds) Landfall Amplifying Jet Stream G-IV Frontal wave stalls AR over CA - AROs MJO 7-10 days UAVs Profilers Ensemble MJO Fcst Recurving West Pacific Tropicals 5-7 days Tropical Tap?

Offshore Monitoring- Gap Filling Radar Demonstration in HMT 34

NEXRAD precipitation estimation errors and error sources quantified Matrosov, S.Y., F.M. Ralph, P.J. Neiman, A.B. White, 2014: Quantitative assessment of operational weather radar rainfall estimates over California s Northern Sonoma County using HMT-West data. J. Hydrometeor, 15, 393 410.

Sensor List 100 new low-mid altitude soil moisture observing sites 125 existing high-altitude sites with new snowrelated data 100 new GPS-met observing sites 25 snow-level radars 25 wind profiling/aro sites 14 C-band scanning radars 10 X-band scanning radars or mini CASA networks 36

Monitoring Atmospheric Conditions That Fuel Extreme Precipitation & Flood New Snow and Streamflow Monitoring for Better Snow Melt Forecasts Offshore Monitoring to Extend Forecast Lead Times for Extreme Precipitation Atmospheric River Observatories to Fill Largest Single Monitoring Gap 37

Atmospheric Rivers (fall and winter) Great Plains Deep Convection (spring and summer) Spring Front Range Upslope (rain/snow) Scripps Institution of Oceanography Center for Western Weather and Water Extremes Southwest Monsoon (summer & fall) Where: When: Start - 2013 Who: UCSD/Scripps Inst. Oceanography La Jolla, California Dr. F. M. Ralph (Director) Dr. Dan Cayan Dr. Mike Dettinger Dr. Ryan Spackman Mission Provide 21 st Century water cycle science, technology and outreach to support effective policies and practices that address the impacts of extreme weather and water events on the environment, people and the economy of Western North America Goal Revolutionize the physical understanding, observations, weather predictions and climate projections of extreme events in Western North America, including atmospheric rivers and the North American summer monsoon as well as their impacts on floods, droughts, hydropower, ecosystems and the economy

CalWater 2 - Science White Paper

HMT-West innovations were key elements in NOAA s rapid response to a flood risk crisis USACE was considering taking over operation of a dam in Washington State during a recent storm. Using the HMT ARO at the coast and NWS forecasts, USACE saw the back edge of the AR was coming ashore and thus heavy rain was about to end, so they did not take over operation from the local water agency. Dept. of Commerce Bronze Medal 2012 See recent journal article by White et al. (February 2012; Bulletin of the American Meteorological Society).

Reservoir Operation Decision - example Courtesy of Larry Schick, US Army Corps of Engineers - Seattle During this current AR rain event, I have found the Westport ARO (for Wynoochee dam) and Spanaway ARO (for HH dam) very useful in short range forecast information which I needed to consult our water management people. The question was whether to take over the dam and operate for flood control today. We were right on the threshold of taking over Wynoochee today for flood control, but had high confidence we didn't need to with the ARO info that the rain would taper off quickly -- and it did. The Spanaway ARO is currently catching the brief heavy ran increase for HHD, but we remain confident it will move on as per forecast. Clearly the ARO info with radar, sat pix and precip trends gave us good confidence today.

2 dropsonde transects by the Global Hawk drone across tropical tap region of an AR -37 sondes -16 h flight versus 24 h goal Background image: Integrated Water Vapor from the Global Forecast System, 30 hour forecast, Valid 0600 UTC 12 Feb 42

Buoy-mounted wind profilers Coastal and marine weather prediction suffers from a relative sparseness of coastal and offshore observations. USWRP Report No. 2 noted that the most serious gap in the current observing system for 1-5 day forecasts is the absence of wind profiles, especially over the northeast Pacific Ocean. profiler

Examples of - Surface Observing Systems Precipitation gauges Precipitation disdrometers Real-time data access Rain Snow Surface-Met Soil and Stream Stream level Soil moisture Surface meteorology & snow depth

Remote Sensing Observing Systems 915-MHz wind profiler with RASS ¼-scale 449-MHz wind profiler with RASS Profiling Scanning Precipitation S-band precipitation profiling radar (S-PROF) Boundary Layer C-band scanning Doppler radar (SKYWATER) FM-CW snow-level radar X-band polarimetric, scanning Doppler radar (HYDRO-X) GPS receiver for integrated water vapor

Scanning C-band radars (2 new) Scanning X-band radar (1 new) Atmos. River Observatory (1 new plus 1 from DWR) Precipitation profiling radars (7 new plus 1 from NOAA)

Atmospheric Rivers, Floods and the Water Resources of California by Mike Dettinger, Marty Ralph,, Tapash Das, Paul Neiman, Dan Cayan Water, 2011 (in Press) 25-35% of annual precipitation in the Pacific Northwest fell in association with atmospheric river events An average AR transports the equivalent of 7.5 times the average discharge of the Mississippi River, or ~10 M acre feet/day 35-45% of annual precipitation in California fell in association with atmospheric river events

4 Jan 2008, 1500 UTC Time of max AR bulk flux at BBY: 1500 UTC 4 Jan 4 Jan 2008, 2100 UTC Time of max AR bulk flux at PPB: 2100 UTC 4 Jan 5 Jan 2008, 0300 UTC AR Propagation: ~12 m s -1. ½-day lead time for SoCal Time of max AR bulk flux at GLA: 0300 UTC 5 Jan