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Hydrologic Predictability and Water Year 2009 Predictions in the Columbia River Basin

Hydrologic Predictability and Water Year 2009 Predictions in the Columbia River Basin. Andy Wood Matt Wiley Bart Nijssen Climate and Water Resource Forecasts for the 2009 Water Year UW Climate Impacts Group October 2, 2008, Vancouver, WA. Presentation Outline. 1. Introduction

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Hydrologic Predictability and Water Year 2009 Predictions in the Columbia River Basin

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  1. Hydrologic Predictability and Water Year 2009 Predictions in the Columbia River Basin Andy Wood Matt Wiley Bart Nijssen Climate and Water Resource Forecasts for the 2009 Water Year UW Climate Impacts Group October 2, 2008, Vancouver, WA

  2. Presentation Outline 1. Introduction 2. Current Conditions 3. Predictability in the Columbia R. Basin 4. Climate Predictions 5. Water Year 2009 Streamflow Outlook

  3. The PNW hydrologic cycle Average annual water cycle • soil moisture near annual low • runoff near low • nearly all water year precipitation yet to come • snow season not really underway • evaporation waning PNW * Where we are now on average

  4. ESP 1960 1961 1962 … … 1999 ENSO subset Can adjust IC by assimilating snow or other observations Hydrologic Model-based Forecasting a forecast has two key elements - initial conditions - climate forecast recently observed meteorological data ensemble of met. data to generate forecast Spin-up Forecast ICs* Werner et al. (2003) weighting scheme for traces rather than a subset hydrologic state obs IC = initial conditions

  5. Initial Conditions – Soil Moisture

  6. Soil Moisture Projections

  7. Soil Moisture Projections

  8. Current Soil Moisture Conditions

  9. Is it dry in the Columbia R. Basin? Last year’s snowpack was good to great, but was based on normal or below precipitation in places USDA/NRCS

  10. Is it dry in the Columbia R. Basin? Then, late summer was fairly dry…

  11. What do the streamflows say? ID

  12. What do the streamflows say? BC

  13. What do the streamflows say? BC

  14. What do the streamflows say? BC

  15. What do the streamflows say? BC

  16. What do the streamflows say? BC

  17. What do the streamflows say? BC

  18. But how much do ICs matter in Fall? • 3TIER was recently funded by NOAA (SBIR) to run a massive set of ensemble hindcasts. • 56 years (1949-2005) of 56-member ESP forecasts for 72 locations in the PNW • archived streamflow, climate and water balance variables at a daily timestep • 1-year lead time forecasts • 6 start dates: 1st day of Nov, Dec, Jan, Feb, Mar, Apr • Many applications: • measure model-based prediction skill • calculate forecast corrections

  19. For every combination of historical IC with met. forecast… what fraction of normal runoff was produced? wettest obs IC + wettest met year driest obs IC + driest met year Nov. 1 Forecast

  20. Early in the water year, wet IC adds < 10% dry IC removes < 10% from April-July flow forecast Nov. 1 Forecast

  21. As water year progresses, ICs become more important precip forecasts less important Dec. 1 Forecast

  22. By January 1, knowing ICs is becoming as important as knowing future climate, for Apr-July flow prediction Jan. 1 Forecast

  23. In February – April, the shift to the dominance of ICs (snow and soil moisture) progresses. Feb. 1 Forecast

  24. In February – April, the shift to the dominance of ICs (snow and soil moisture) progresses. Mar. 1 Forecast

  25. On April 1, the difference between the wettest & driest Spring met for forecast Apr-Jul flow is minor. Apr. 1 Forecast

  26. Given average precipitation in October, where will The Dalles forecast be on Nov. 1 this year?

  27. Climate Prediction THIS YEAR

  28. 2008 La Nina versus Normal conditions: Oct-Dec precip temperature SWE soil moist runoff oct nov dec

  29. 2008 La Nina versus Normal conditions: Jan-Mar precip temperature SWE soil moist runoff jan feb mar

  30. 2008 La Nina versus Normal conditions: Apr-Jun precip temperature SWE soil moist runoff apr may jun

  31. Current ENSO Forecasts… ….mostly point toward a neutral winter: http://iri.columbia.edu/climate/ENSO/currentinfo/figure3.html

  32. Yet a few are turning toward La Nina… http://www.cdc.noaa.gov/people/klaus.wolter/MEI/

  33. US and Europe agree on something? NCEP A number of forecasts update within the next week – worth checking at: http://iri.columbia.edu/climate/ENSO/currentinfo/modelviews.html ECMWF

  34. Where NOAA fears to tread… http://www.almanac.com/weather/index.php

  35. Water Year 2009 Forecasts

  36. 2009 Natural Runoff Volume Forecasts Columbia River at Mica Dam percent of normal (‘71-’00) for period Jan-Jul Apr-Jul Apr-Sep 97 97 98

  37. 2009 Natural Runoff Volume Forecasts Pend Oreille River at Albeni Falls Dam percent of normal (‘71-’00) for period Jan-Jul Apr-Jul Apr-Sep 99 99 99

  38. 2009 Natural Runoff Volume Forecasts Columbia River at Grand Coulee Dam percent of normal (‘71-’00) for period Jan-Jul Apr-Jul Apr-Sep 97 97 97

  39. 2009 Natural Runoff Volume Forecasts Snake River below Lower Granite Dam percent of normal (‘71-’00) for period Jan-Jul Apr-Jul Apr-Sep 89 89 90

  40. 2009 Natural Runoff Volume Forecasts Columbia River at The Dalles, OR percent of normal (‘71-’00) for period Jan-Jul Apr-Jul Apr-Sep 95 95 95

  41. 2009 Natural Runoff Volume Forecasts Summary percent of normal (71-00) for period Name Jan-Jul Apr-Jul Apr-Sep Columbia River at The Dalles, OR 95 95 95 Columbia River at Grand Coulee Dam 97 97 97 Snake River below Lower Granite Dam 89 89 90 Pend Oreille River at Albeni Falls Dam 99 99 99 Columbia River at Mica Dam 97 97 98

  42. thank you! questions? awood @ 3tiergroup.com

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