Seasonal outlooks for hydrology and water resources in the Pacific Northwest Andy Wood Alan Hamlet Dennis P. Lettenmaier Department of Civil and Environmental.

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 MoistureInitial

Condition

SnowpackInitial 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 Hydrology 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

ICsSpin-up Forecast

obs

recently observedmeteorological data

ensemble of met. datato generate forecast

ESP forecast

hydrologicstate

targeted statisticse.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

  <==== Drier === Future Conditions === Wetter ====>  

Forecast Pt ============ Chance of Exceeding * ===========  

   Forecast 90% 70% 50% (Most Prob) 30% 10% 30 Yr Avg

   Period (1000AF) (1000AF) (1000AF) (% AVG.) (1000AF) (1000AF) (1000AF)

MARY'S R nr Deeth, Nv

APR-JUL 12.3       18.7       23       59       27       34       39      

MAY-JUL 4.5       11.3       16.0       55       21       28       29      

LAMOILLE CK nr Lamoille, Nv

APR-JUL 13.7       17.4       20       67       23       26       30      

MAY-JUL 11.6       15.4       18.0       64       21       24       28      

N F HUMBOLDT R at Devils Gate

APR-JUL 5.1       11.0       15.0       44       19.0       25       34      

MAY-JUL 1.7       7.2       11.0       50       14.8       20       22      

Winter 2004-05: seasonal volume forecast for APR-SEP flow

ESP median, 10th & 90th %-ilesESP-ENSO (warm) median

OBS

Forecasts made on 1st of Month

Winter 2004-05: seasonal volume forecast for APR-SEP flow

ESP median, 10th & 90th %-ilesESP-ENSO (warm) median

OBS

Forecasts made on 1st of Month

Winter 2004-05: seasonal volume forecast for APR-SEP flow

ESP median, 10th & 90th %-ilesESP-ENSO (warm) median

OBS

Forecasts made on 1st of Month

Winter 2004-05: seasonal volume forecast for APR-SEP flow

ESP median, 10th & 90th %-ilesESP-ENSO (warm) median

OBS

Forecasts made on 1st of Month

Winter 2004-05: seasonal volume forecast for APR-SEP flow

ESP median, 10th & 90th %-ilesESP-ENSO (warm) median

OBS

Forecasts made on 1st 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

0.75median0.25

min

spinup

Oct 1 ESP fcst: WY2006 Precip, Temp

Columbia R. basin upstream of The

Dalles, OR

Precip Temp

2005 2006 2005 2006

Oct 1 ESP fcst: WY2006 SM, SWE, RO

Runoff

hangover fromlast year’s soil moisture deficitApr-Sep % of

avg

ESP: 98%ENSO: 95%

Soil Moist

SWE

2005 2006

Oct 1 ESP fcst: WY2006 Precip, Temp

Precip Temp

2005 2006

Puget Sound Drainage Basin

2005 2006

Oct 1 ESP fcst: WY2006 SM, SWE, RO

Apr-Sep % of avg

ESP: 98%ENSO: 96%

Runoff

Soil Moist

SWE2005 2006

Oct 1 ESP fcst: WY2006 Precip, Temp

Precip Temp

2005 2006

Yakima R. Basin near

Parker, WA

2005 2006

Oct 1 ESP fcst: WY2006 SM, SWE, RO

Apr-Sep % of avg

ESP: 93%ENSO: 90%

RunoffSoil Moist

SWE2005 2006

Oct 1 ESP fcst: WY2006 Precip, Temp

Precip Temp

2005 2006 2005 2006

BC portion of Columbia R. Basin

Oct 1 ESP fcst: WY2006 SM, SWE, RO

Apr-Sep % of avg

ESP: 101%ENSO: 99%

RunoffSoil Moist

SWE2005 2006

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:

www.hydro.washington.edu / 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