Recap of Water Year 2008 Hydrologic Forecast and Forecasts for Water Year 2009

Francisco Munoz-ArriolaAlan F. Hamlet Shraddhanand ShuklaDennis P. Lettenmaier

•JISAO/CSES Climate Impacts Group Dept. of Civil and Environmental Engineering

University of Washington

Recap of WY 2008

ECMRWF ENSO anomaly 2008

European Centre for Medium-Range Weather Forecasts

Validation Plot for 2008 Forecast (All Cool ENSO composite)

Mod

ified

Flo

w (

cfs)

The Dalles

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250000

300000

350000

400000

450000

-3 -2 -1 0 1 2 3 4

NINO3.4 Index Anomaly

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ril-

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1916-2002

April-September Naturalized Flow for the Columbia River at The Dalles, OR from Historic Water Years vs January Nino 3.4 Anomalies.

5000

10000

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-3 -2 -1 0 1 2 3 4

Nino 3.4 Anomaly (C)

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il-S

epte

mbe

r A

vg N

atur

aliz

ed

Str

eam

flow

(cf

s)

Natural Flows at Milner 1928-1989

Nat

ural

Flo

w (

KA

F)

Red = long term meanBlue = ensemble meanGray = ensemble membersBlack = range of observations

Simulated Natural Flow at Milner (ESP all years)

Milner

Nat

ural

Flo

w (

KA

F)

Red = long term meanBlue = ensemble meanGray = ensemble membersBlack = range of observations

Simulated Natural Flow at Milner (ESP cool ENSO)

Milner

WY 2008 Forecast

WY 2007 WY 2008

Potential Implications of ENSO Transition States

WY 2009

http://www.ecmwf.int/products/forecasts/d/charts/seasonal/forecast/seasonal_range_forecast/nino_plumes_public_s3/

European Centre for Medium-Range Weather Forecasts

ECMRWF ENSO anomaly 2009

0.2

-0.6

150000

200000

250000

300000

350000

400000

450000

-3 -2 -1 0 1 2 3 4

NINO3.4 Index Anomaly

Ap

ril-

Se

pte

mb

er

Av

era

ge

S

tre

am

flo

w1916-2002

April-September Naturalized Flow for the Columbia River at The Dalles, OR from Historic Water Years vs January Nino 3.4 Anomalies.

Natural Flows at Milner 1928-1989

West-Wide Hydrologic Forecast

UW Forecast Approach Schematic

NCDC COOP station obs.

up to 3 months from

current

local scale (1/8 degree) weather inputs

soil moisturesnowpack

VIC Hydrologic model spin up

SNOTEL

Update

streamflow, soil moisture, snow water equivalent, runoff

25th Day, Month 01-2 years back

index stn. real-time

met. forcings for spin-up

gap

Hydrologic forecast simulation

Month 12

INITIAL STATE

ObservedSWE

Assimilation

ensemble forecasts ESP traces CPC-based outlook NCEP CFS ensemble NSIPP-1 ensemble

West-wide System

Ensemble Streamflow Prediction (ESP)

ICsSpin-up Forecast

observed

recentmet data to generate

“perfect” ICs

ensemble of historical met datato generate ensemble

forecast

hydrologicstate

Applications: climate forecast

Soil Moisture and Snow Water Anomalies

SWE and SM

SimulatedClimatological

March AprilFebruary

SWE and SM

SimulatedClimatological

MarchFebruary April

July August September

Based on Milner Climatology 1960-2005

All Years

Ensemble Mean

Climatological Mean

Ensemble Members

Climatological Extremes

0

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1000000

S O N D J F M A M J J A

Nat

ura

l Str

eam

flo

w (

cfs)

Based on Dalles Climatology 1901-2005

All Years

Ensemble Mean

Climatological Mean

Ensemble Members

Climatological Extremes

Based on Milner Climatology 1960-2005

ENSO-Neutral Years

Ensemble Mean

Climatological Mean

Ensemble Members

Climatological Extremes

0

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1200000

S O N D J F M A M J J A

Nat

ura

l Str

eam

flo

w (

cfs)

Based on Dalles Climatology 1901-2005

ENSO-Neutral Years

Ensemble Mean

Climatological Mean

Ensemble Members

Climatological Extremes

3.4 Range 2009

-0.6 to 0.2

Based on Milner Climatology 1901-2005

Ensemble Mean

Climatological Mean

Ensemble Members

Climatological Extremes

0

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400000

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1200000

S O N D J F M A M J J A

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3.4 Range 2009

-0.6 to 0.2

Based on Dalles Climatology 1901-2005

Ensemble Mean

Climatological Mean

Ensemble Members

Climatological Extremes

West-Wide Hydrologic Forecast

West Wide Forecast (1961-2000)

All Years

Ensemble Mean

Climatological MeanEnsemble Members

Climatological Extremes

ENSO-years Mean (N)

Milner

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eam

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West Wide Forecast (1961-2000)

All Years

Ensemble Mean

Climatological MeanEnsemble Members

Climatological Extremes

ENSO-years Mean (N)

Dalles

ENSO-Neutral Years

West Wide Forecast (1961-2000)

Ensemble Mean

Climatological MeanEnsemble Members

Climatological Extremes

ENSO-years Mean (N)

Milner

0

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400000

600000

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1000000

S O N D J F M A M J J A

Na

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)

ENSO-Neutral Years

West Wide Forecast (1961-2000)

Ensemble Mean

Climatological MeanEnsemble Members

Climatological Extremes

ENSO-years Mean (N)

Dalles

3.4 Range 2009

-0.6 to 0.2

West Wide Forecast (1961-2000)

Ensemble Mean

Climatological MeanEnsemble Members

Climatological Extremes

ENSO-years Mean (N)

Milner

0

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3.4 Range 2009

-0.6 to 0.2

West Wide Forecast (1961-2000)

Ensemble Mean

Climatological MeanEnsemble Members

Climatological Extremes

ENSO-years Mean (N)

Dalles

UW Forecast System in the Snake River

Hells Canyon Dam

Milner

UW Forecast System in the Hydropower-related stations at the

Columbia River

Grand Coulee

Chief Joseph Dam

Conclusions:•Cool ENSO event during the winter of 2007-2008, increased above average Apr-Sep flow at Milner•High snowpack during winter-spring was associated with low values in soil moisture•The WY 2008 ESP forecast predicted increased likelihood of wet conditions. Observed summer flows at Milner in 2007 were above average (~25% of normal for April-Sept)•Current soil moisture conditions may contribute to slightly reduce streamflow generation during the Jan-June period by 3%.•The west-wide forecast system predicts flows similar to those observed in the climatologies for the Dalles , However for the Milner stations there is a increased likelihood of drought and consequently flows slight below normal for the coming water year.•Slightly below 1961-2000 climatological values•Slightly above -0.6-to-0.2 ENSO neutral values•On the average of ENSO neutral years

WY 2007 WY 2008

Potential Implications of ENSO Transition States

1904 1.47

1907 1.00

1921 1.00

1925 0.49

1932 0.39

1943 0.88

1965 0.90

1971 1.55

1974 2.22

1984 0.58

1989 -0.40

1996 0.93

1999 0.89

Historic Dalles Apr-Sept streamflow anomalies for water years with previous winter warm ENSO, current winter cool ENSO

Stats:

12 of 13 above 0.39

11 of 13 above 0.49

9 of 13 above 0.88

WY Std Ann.

Nat

ural

Str

eam

flow

(cf

s)Based on Dalles Climatology 1901-2003

1932 -0.235

1943 1.137

1965 1.238

1971 2.170

1974 1.686

1984 1.883

1989 -0.080

Historic Milner Apr-Sept streamflow anomalies for water years with previous winter warm ENSO, current winter cool ENSO

WY Std Ann.

Stats:

5 of 7 above 1.1

3 of 7 above 1.7

enso_2008 enso_trans_2008

Based on Milner ESP 1961-2000N

atur

al F

low

(K

AF

)

Nat

ural

Flo

w (

KA

F)