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

Andy Wood

Matt WileyBart Nijssen

Climate and Water Resource Forecasts for the 2009 Water YearUW Climate Impacts Group

October 2, 2008, Vancouver, WA

Presentation Outline

1. Introduction

2. Current Conditions

3. Predictability in the Columbia R. Basin

4. Climate Predictions

5. Water Year 2009 Streamflow Outlook

Average annual water cycle

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 waning

Hydrologic Model-based Forecasting

ICs*Spin-up Forecast

obs

recently observedmeteorological data

ensemble of met. datato generate forecast

hydrologicstate

IC = initial conditions

ENSO subset

196019611962……

1999

ESP

Can adjust IC by assimilatingsnow or other observations

a forecast hastwo key elements- initial conditions- climate forecast

Werner et al. (2003) weightingscheme for tracesrather than a subset

Initial Conditions – Soil Moisture

Soil Moisture Projections

Soil Moisture Projections

Current Soil Moisture Conditions

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

USDA/NRCS

Then, late summer was fairly dry…

Is it dry in the Columbia R. Basin?

What do the streamflows say? ID

What do the streamflows say? BC

What do the streamflows say? BC

What do the streamflows say? BC

What do the streamflows say? BC

What do the streamflows say? BC

What do the streamflows say? BC

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

Nov. 1Forecast

For every combination of historical IC with met. forecast…

what fraction of normal runoff was produced?

driest obs IC + driest met year

wettest obs IC +wettest met year

Nov. 1Forecast

Early in the water year,

wet IC adds < 10% dry IC removes < 10%

from April-July flow forecast

Dec. 1Forecast

As water year progresses, ICs become more importantprecip forecasts less important

Jan. 1Forecast

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

Feb. 1Forecast

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

Mar. 1Forecast

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

Apr. 1Forecast

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

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

Climate Prediction

THIS YEAR

2008 La Nina versus Normal conditions: Oct-Dec

oct

nov

dec

precip temperature SWE soil moist runoff

2008 La Nina versus Normal conditions: Jan-Mar

jan

feb

mar

precip temperature SWE soil moist runoff

2008 La Nina versus Normal conditions: Apr-Jun

apr

may

jun

precip temperature SWE soil moist runoff

http://iri.columbia.edu/climate/ENSO/currentinfo/figure3.html

Current ENSO Forecasts…

….mostly point toward a neutral winter:

http://www.cdc.noaa.gov/people/klaus.wolter/MEI/

Yet a few are turning toward La Nina…

US and Europe agree on something?

NCEP

ECMWF

A number of forecasts update within the next week – worth checking at:

http://iri.columbia.edu/climate/ENSO/currentinfo/modelviews.html

Where NOAA fears to tread…

http://www.almanac.com/weather/index.php

Water Year 2009 Forecasts

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

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

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

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

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

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

2009 Natural Runoff Volume Forecasts Summary

questions?awood @ 3tiergroup.com

thank you!