Seasonal outlooks for hydrology and water resources in the Pacific Northwest Andy Wood Alan Hamlet Dennis P. Lettenmaier Department of Civil and Environmental Engineering for Climate and Water Resource Forecasts for the 2006 Water Year UW Climate Impacts Group October 26, 2005, Seattle

Presentation Outline 1. Introduction: UW Experimental Hydrologic Forecasting System 2. Water Year 2005 Assessment 3. Water Year 2006 Outlook

Average annual water cycle Introduction: A review of the PNW hydrologic cycle PNW Where we are now on average  soil moisture near annual low  runoff near low  nearly all water year precipitation yet to come  snow season not really underway  evaporation not a factor

Oct 1 ESP fcst: Summer Volumes

Introduction Forecast System Website

Experimental W. US Hydrologic Forecast System Soil Moisture Initial Condition Snowpack Initial Condition

Experimental W. US Hydrologic Forecast System ESP ENSO/PDO ENSO CPC Official Outlooks Coupled Forecast System CAS OCN SMLR CCA CA NSIPP/GMAO dynamical model VIC Hydrolog y Model NOAA NASA UW Multiple Seasonal Climate Forecast Data Sources

Hydrologic prediction using ESP NWS River Forecast Center (RFC) approach: rainfall-runoff modeling (i.e., NWS River Forecast System, Anderson, 1973 offspring of Stanford Watershed Model, Crawford & Linsley, 1966) Ensemble Streamflow Prediction (ESP) used for shorter lead predictions; increasingly used for longer lead predictions ICs Spin-upForecast obs recently observed meteorological data ensemble of met. data to generate forecast ESP forecast hydrologic state

targeted statistics e.g., runoff volumes monthly hydrographs spatial forecast maps

Presentation Outline 1. Introduction: UW Experimental Hydrologic Forecasting System 2. Water Year 2005 Assessment 3. Water Year 2006 Outlook

Recap WY2005, Dec. 1 hydrologic conditions

Recap WY2005, Jan. 1 hydrologic conditions

Recap WY2005, Feb. 1 hydrologic conditions

Recap WY2005, Mar. 1 hydrologic conditions

Recap WY2005, Apr. 1 hydrologic conditions

Recap WY2005, May. 1 hydrologic conditions

Recap WY2005, Jun. 1 hydrologic conditions

Current WY2005, Oct. 1 hydrologic conditions

Oct. 1 Soil Moisture Comparison THIS YEAR LAST YEAR

Streamflow volume forecasts UPPER HUMBOLDT RIVER BASIN Streamflow Forecasts - May 1, 2003 Forecast Pt============ Chance of Exceeding * =========== Forecast90%70%50% (Most Prob)30%10%30 Yr Avg Period(1000AF) (% AVG.)(1000AF) MARY'S R nr Deeth, Nv APR-JUL MAY-JUL LAMOILLE CK nr Lamoille, Nv APR-JUL MAY-JUL N F HUMBOLDT R at Devils Gate APR-JUL MAY-JUL

Winter : seasonal volume forecast for APR-SEP flow ESP median, 10 th & 90 th %-iles ESP-ENSO (warm) median OBS Forecasts made on 1 st of Month

Winter : seasonal volume forecast for APR-SEP flow ESP median, 10 th & 90 th %-iles ESP-ENSO (warm) median OBS Forecasts made on 1 st of Month

Winter : seasonal volume forecast for APR-SEP flow ESP median, 10 th & 90 th %-iles ESP-ENSO (warm) median OBS Forecasts made on 1 st of Month

Winter : seasonal volume forecast for APR-SEP flow ESP median, 10 th & 90 th %-iles ESP-ENSO (warm) median OBS Forecasts made on 1 st of Month

Winter : seasonal volume forecast for APR-SEP flow ESP median, 10 th & 90 th %-iles ESP-ENSO (warm) median OBS Forecasts made on 1 st of Month

Presentation Outline 1. Introduction: UW Experimental Hydrologic Forecasting System 2. Water Year 2005 Assessment 3. Water Year 2006 Outlook

Basin Average Water Balance Perspective Averaging water balance variables over a region can help characterize the evolution of the water year forecast distribution max 0.75 median 0.25 min spinup

Oct 1 ESP fcst: WY2006 Precip, Temp Columbia R. basin upstream of The Dalles, OR Precip Temp

Oct 1 ESP fcst: WY2006 SM, SWE, RO Runoff hangover from last year’s soil moisture deficit Apr-Sep % of avg ESP: 98% ENSO: 95% Soil Moist SWE

Oct 1 ESP fcst: WY2006 Precip, Temp Precip Temp Puget Sound Drainage Basin

Oct 1 ESP fcst: WY2006 SM, SWE, RO Apr-Sep % of avg ESP: 98% ENSO: 96% Runoff Soil Moist SWE

Oct 1 ESP fcst: WY2006 Precip, Temp PrecipTemp Yakima R. Basin near Parker, WA

Oct 1 ESP fcst: WY2006 SM, SWE, RO Apr-Sep % of avg ESP: 93% ENSO: 90% Runoff Soil Moist SWE

Oct 1 ESP fcst: WY2006 Precip, Temp Precip Temp BC portion of Columbia R. Basin

Oct 1 ESP fcst: WY2006 SM, SWE, RO Apr-Sep % of avg ESP: 101% ENSO: 99% Runoff Soil Moist SWE

Conclusions  It’s still early in year for hydrologic forecasts, especially in an ENSO neutral year  Most PNW basins have land surface tendency for being on dry side by 3-10 percent:  exceptions: south edge of Snake R. basin, also BC  The parts of the region that receive higher rainfall (west of the Cascades) are more likely to recover from moisture deficits from last year.

Questions? website: / forecast / westwide /

Seasonal Climate Prediction e.g., precipitation

CPC Temperature Outlook

CPC Precipitation Outlook

3/15 ESP fcst: WY2006 vs. WY1977 Precip, Temp Snake River basin