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Roadmap for Hydrologic Ensemble Forecast Services

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Outline

• Challenges• Solution – Seamless suite of Hydrologic Ensemble

Forecast Services (HEFS)– Current vs. HEFS– Key HEFS Components– Status and Schedule

• Field Testing– Budget

• Issues and Risks

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Background: Water Forecasting Challenges

• Implement mature hydrologic science into NWS operations within the constraints of existing infrastructure (data, IT, and people)

• Calibrate and enhance hydrologic modeling systems for multiple time scales and over diverse hydroclimatic regimes

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Problem

• Current short-range river forecasts are single-valued• RFC forecasters examine selected set of “what-if” scenarios• Other ensemble products include bias• No integration of short, medium, long range NWP forecasts

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Objective: Ensemble Based Probabilistic Forecast Products

• Run ensembles of inputs through river models to generate hydrologic forecasts

• Analyze ensemble information to quantify forecast uncertainty and produce a full range of possible hydrologic scenarios

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Hydrologic Ensemble Forecast Services (HEFS)

• End-to-end hydrologic ensemble forecast service currently under development

– Comprehensive plan developed in 2007 (the first of its kind in the world)

– Based and built on leading-edge science and technology

– OHD collaborating with NCEP, OAR and universities through:• The Observing-System Research and Predictability Experiment (THORPEX)

• Climate Prediction Program for the Americas (CPPA) Core Project

• The Hydrologic Ensemble Prediction Experiment (HEPEX)

• Research grants

• Field deployment via the Community Hydrologic Prediction System (CHPS)

• Experimental (prototype) components under evaluation at some RFCs

• Additional prototype deployments during the next 2 years

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Current (Seasonal ESP) vs. HEFS

Feature Current HEFS

Platform NWSRFS(inflexible, outdated)

CHPS (flexible, modern)

Forecast Horizon

Weeks to Seasons Hours to Years

NCEP Input None CPC, EMC, HPC

Bias Correction None NCEP InputsHydro Model Outputs

Hydro model uncertainty

Not addressed Addressed

Output format Limited number of simple graphics based on Ensemble Streamflow Prediction (ESP)

Web-enabled interactive toolbox

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Weather & Climate Forecasts

Assess Hydrologic Model Error

Correct NCEP Model Bias

Create Hydrologic Ensembles

Hydrologic Ensemble Prediction System:Key Components

AssimilateData

Correct Hydrologic Ensemble Bias

QPE, QTE, Soil Moisture

Streamflow

Verificatio

n S

ystem

Generate Product

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IFP

OFS

Raw flow ens.

Pp’ed flow ens.

Ensemble Verification

System

Flow Data

Product Generation Subsystem

Ensemble verification

products

Hydrologic Ensemble Hindcaster

Ens. User Interface

EPP User Interface

Ens. Pre-Processor

Atmospheric forcing data

Ensemble/prob.

products

Ens. Post-Proc.

Ens. Streamflow Prediction

System

HMOS Ensemble Processor

MODs

EPP3 ESP2 EnsPost EPG

EVS

Hydro-meteorol. ensembles

XEFS Graphical User Interface

Web Inter-face

XEFS linkage: XEFS linkage: EXperimental Ensemble Forecast System (XEFS)EXperimental Ensemble Forecast System (XEFS)

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Hist. RFC s.-v. fcst

Hist. obs

GFS ens. mean refcst

RFC stat. parameters

GFS stat. parameters

Real-time RFC fcst

Real-time GFS fcst

Strat. Cond. Simulation

Strat. Cond. simulation

Hist. ens.

Prob. M. & S. Shuffle

Prob. M. & S. Shuffle.

Joining / Blending

CFS ens. refcst

CPC outlook fcst

CFS stat. parameters

Real-time CFS fcst

Strat. Cond. simulation

Probability shifting

Prob. M. & S. Shuffle

Day 1-to-5 ens.

Day 1-to-14 ens.

Day 15~ ens

Ens. fcsts

Climate indices

Samp. from Hist. ens.

Day 15~ ens.

Merging of RFC & GFS Day 1-5 ens.

Merging Day 15~ fcsts

Generic ens.

Parameter estimation

Day 15~ ens.

Merged Day 1-5 ens.

Merged Day 15~ fcsts

Parameter estimation

Parameter estimation

Hist. ens.

Hist. obs

Hist. ens.

Short-Range

Medium-Range

Long-Range

Merging, Joining & Blending

Proposed HEFS Components Proposed HEFS Components

Other Ensembles

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Ensemble Pre-Processor

Hydrologic Model Output Statistics

(HMOS) Ensemble Processor

Ensemble Verification

Hydrologic Ensemble Hindcaster

HEFS – Field Testing

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Today

CHPS and HEFS Deployment Plans

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HEFSPrototype components development

Develop software-engineered AWIPS II baseline software

9 RFCs4 RFCs

HEFS capabilities first available to RFCs

2008 2009 2010 2011 2012FY

CHPS

Hydrology Program Funding

FY08 FY09 FY10 FY11

CHPS $1.2M $2.8M $2.5M $1.0M

HEFS $1.5M $1.2M $1.2M $1.2M

Funds two NCEP staff

and two collaborativeresearch grants

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HEFS Challenges

• Science– HEFS is a tool; research continues on how best to use that tool

• How to produce hydrologic ensemble forecasts based on meteorological ensembles

– Extreme events (e.g. record flooding) are harder to monitor and forecast:• Record conditions are outside model limits without historical analogs

– Products must be understandable / actionable– Forecast cone must be small enough for effective decision support

• Better accuracy required from both met and hydro models

• Implementation– Prototype software is not baseline software

• OHD staff to implement HEFS is focused on CHPS into 2011

• Delivery with CHPS will be prototype code integrated into FEWS

– RFCs will need to calibrate HEFS– We need to train forecasters– Web farms will need to handle more complex data requests– RFCs will require additional computer resources to operate in an ensemble mode

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Issues and Risks

Issue/Risk Mitigation Strategy Assistance

AWIPS II delays will result in further delay of AHPS research-to-operations (e.g., quantification of short-term uncertainty)

The Community Hydrologic Prediction System (CHPS) will be deployed with AWIPS II to support robust enhancements to the core river forecasting system

Maintain high priority focus on AWIPS II

CHPS delays will defer ensemble forecast system deployment

Maintain high priority focus on CHPS and short-range ensemble techniques

None