nws ~ northwest river forecast center seasonal volume forecasts using ensemble streamflow prediction...

NWS ~ NorthWest River Forecast Center

Seasonal Volume ForecastsSeasonal Volume ForecastsUsing Ensemble Streamflow PredictionUsing Ensemble Streamflow Prediction

for the 2006 Water Yearfor the 2006 Water Year

Kevin Berghoff, HydrologistNorthwest River Forecast Center

October 13, 2005


Topics for Presentation

Northwest River Forecast Center:Northwest River Forecast Center: Overview Overview

NWRFC Forecasting Models and ProductsNWRFC Forecasting Models and Products NWS River Forecast System (NWSRFS) NWS River Forecast System (NWSRFS) Statistical Water Supply ForecastsStatistical Water Supply Forecasts

Use of the Ensemble Streamflow Prediction (ESP) model Use of the Ensemble Streamflow Prediction (ESP) model to Produce Longterm Forecasts to Produce Longterm Forecasts 2006 Volumetric Outlook2006 Volumetric Outlook Incorporation of Climate Forecasts into ESP Incorporation of Climate Forecasts into ESP

(experimental)(experimental)


Northwest River Forecast CenterNorthwest River Forecast Center

Total Area: 315,795

Grand Coulee Dam

The Willamette at Salem

The Dalles Dam

Lower Granite Dam

Columbia and Columbia and Snake River Snake River BasinsBasins

Coastal Coastal Drainages of Drainages of Oregon and Oregon and WashingtonWashington

6 States & 6 States & CANADACANADA

Support forSupport for9 NWS Field 9 NWS Field Offices (WFOs)Offices (WFOs)


NWRFC Forecasting Models

NWS River Forecast SystemNWS River Forecast System Short, Medium, and Longterm capabilities Short, Medium, and Longterm capabilities

Generate output in deterministic Generate output in deterministic ANDAND probabilistic (ESP) formats probabilistic (ESP) formats 2 Outputs for ESP2 Outputs for ESP

Match Regression based Water Supply (147 points) Natural ESP (all 302 fx points)

Statistical Water Supply Statistical Water Supply Seasonal ForecastsSeasonal Forecasts

Regression techniquesRegression techniques


Hydrologic Forecasting:Time Domains

Time

Fl ow


NWSRFS:NWSRFS:Ensemble Streamflow Prediction (ESP)Ensemble Streamflow Prediction (ESP)

PrecipitationTemperature

Model Operations

Model States

Model Parameters

Observed Inputs

EnsembleForecast Inputs(10 day QPF + historical record)

EnsembleForecast Outputs(traces)

ProbabilisticProducts


19871987

ESP Output Trace Ensemble PlotESP Output Trace Ensemble Plot

1971 1959

10 Day QPF


1959

1989

1954


Sensitivity of Initial Conditions:Sensitivity of Initial Conditions:September Soil MoistureSeptember Soil Moisture

NWSRFS has a memory for soil moisture that extends many weeks into the future

This memory can be exploited for the purpose of producing spring outlooks


Historically used to generate Volume Historically used to generate Volume ForecastsForecasts

Products: Products: FinalFinal (Coordinated with NRCS)Early BirdEarly BirdMid-MonthMid-MonthContingency Contingency (future precip 50%, 75%, 125% of normal)(future precip 50%, 75%, 125% of normal)

Forecasts:Forecasts:147 Forecast Points - 45 above Grand Coulee Dam147 Forecast Points - 45 above Grand Coulee Dam - 63 in the Snake Basin- 63 in the Snake Basin

- 39 in the Lower - 39 in the Lower Columbia Columbia

Regression Based Water Supply Regression Based Water Supply ForecastsForecasts


Regression Water Supply and Regression Water Supply and Observed RunoffObserved Runoff

Jan-Jul Volume 2005 Forecast

Jan-Jul Volume 30 yr Normal

2005 Jan-Jul Cumulative Observed Volume 81.39 MAF – 76%


Regression Water Supply/ESP Regression Water Supply/ESP Volume ForecastVolume Forecast

2005 Regression Water Supply Forecast

2005 50% Exceedance ESP Water Supply Forecast

2006 50% Exceedance ESP Water Supply Forecast


2006 Spring Outlook2006 Spring Outlook

Ensemble Streamflow Prediction (ESP)Ensemble Streamflow Prediction (ESP) Official Statistical Water Supply PointsOfficial Statistical Water Supply Points Natural ESP Volume Forecast for all PointsNatural ESP Volume Forecast for all Points

Eastside and WestsideEastside and Westside

Updated weeklyUpdated weekly

Driven by Antecedent Snow/Soil Moisture, 10 day Precip and Temperature ForecastDriven by Antecedent Snow/Soil Moisture, 10 day Precip and Temperature Forecast

Soon to incorporate climate forecastsSoon to incorporate climate forecasts


Climate DiscussionsClimate Discussions

CPC ENSO Discussion – Oct 6, 2005CPC ENSO Discussion – Oct 6, 2005 ……ENSO neutral conditions expected during the next 3-6 ENSO neutral conditions expected during the next 3-6

months…months… UW Climate Impacts Group – Aug 19, 2005UW Climate Impacts Group – Aug 19, 2005

……increased odds of above avg air temps for the next 3 to increased odds of above avg air temps for the next 3 to 6 months…no indication of a shift in odds for above or 6 months…no indication of a shift in odds for above or below normal precip…below normal precip…

International Research Institute for Climate International Research Institute for Climate Prediction – Sept 14, 2005Prediction – Sept 14, 2005 … … 90-95% likely that neutral conditions will prevail 90-95% likely that neutral conditions will prevail

through the end of 2005through the end of 2005


The Dalles vs SOIThe Dalles vs SOI


2006 Spring Outlook2006 Spring Outlook50% Exceedance Volume - MAF50% Exceedance Volume - MAF

63.8 MAF – 101%26.7 MAF – 89%

98.5 MAF – 92 %


2005 Forecast Comparison2005 Forecast Comparison

ESP/Regression Based Water Supply ComparisonColumbia R at the Dalles2005 Jan-Jul Volume - kaf

6000065000700007500080000850009000095000

100000105000110000

Jan Feb Mar Apr May Jun Jul

Month

vo

lum

e -

ka

f

ESP Regression Water Supply

30 yr Normal - 107300 kaf

2005 Jan-Jul Observed Runoff - 81349 kaf

75% 30% 109% 101% 150% 141% 65%

80%


Effects of Current Model States Effects of Current Model States and QPF Inputand QPF Input

Initial Conditions/QPF Effects2006 Jan-Jul ESP volume at Dworshak Dam

3300

3350

3400

3450

3500

3550

3600

1-Sep 6-Sep 11-Sep 16-Sep 21-Sep 26-Sep 1-Oct 6-Oct

2005 Forecast Date

Jan

-Ju

l V

olu

me

- ka

f


Using Climate Forecasts with ESPUsing Climate Forecasts with ESPTemperature and PrecipTemperature and Precip Seasonal OutlooksSeasonal Outlooks


Taking Advantage of Climate Forecasts: Taking Advantage of Climate Forecasts: ESP Pre-Adjustment TechniqueESP Pre-Adjustment Technique

Climate Forecast Probabilities usedto skew the distribution of ESP inputs(historical temp/precip record)


Yearly Weights applied to ESP traces Yearly Weights applied to ESP traces

Weights are based on the similarity of a Weights are based on the similarity of a historical year to the current yearhistorical year to the current year

Can be used to exclude historical yearsCan be used to exclude historical years

Taking Advantage of Climate Forecasts: Taking Advantage of Climate Forecasts: ESP Post-Adjustment TechniqueESP Post-Adjustment Technique


www.nwrfc.noaa.govwww.nwrfc.noaa.gov Water Forecasts: 0 - 14 Days 14 - 120 Days Water Supply Peak Flow AHPS Watch & Warnings Flood Outlook Discussion Past Floods River Photos Dambreak Hydrologic Cycle

Weather Snow Observations Forecasts Exp Forecasts Temp & Precip Forecasts

www.nwrfc.noaa.govwww.nwrfc.noaa.govWater Forecasts: 0 - 14 Days 14 - 120 Days Water Supply Peak Flow AHPS Watch & Warnings Flood Outlook Discussion Past Floods River Photos Dambreak Hydrologic Cycle

Weather Snow Observations Forecasts Exp Forecasts Temp & Precip Forecasts

www.nwrfc.noaa.govwww.nwrfc.noaa.govClimate Climate Forecasts Drought Assessment Hazard Assessment Indexes Monthly Means Return Periods

NWRFC Office Information Internal Web SDM Schedule Staff Employment Projects Papers Presentations Contact Us

Links River Centers Weather Offices NWS Offices


NWRFC: WebsiteNWRFC: Website

5241 NE 122nd Avenue5241 NE 122nd AvenuePortland, OR 97230Portland, OR 97230

www.nwrfc.noaa.govwww.nwrfc.noaa.gov

(co-located with Portland (co-located with Portland Weather Forecast Office)Weather Forecast Office)

nws ~ northwest river forecast center seasonal volume forecasts using ensemble streamflow prediction...

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