Climate Prediction Applications Science Workshop Jim Noel Senior Hydrologist NOAA/ National Weather Service Ohio River Forecast Center March 4, 2008

Outline History of Flood Outlooks Why change now? Ensemble Streamflow Prediction (ESP) Climate Forecasts within ESP Experimental Water Resources Outlooks Expansion of Climate Products – Examples Summary

History Subjective in nature Only produced in flood season Based on series of text products Subjective in nature Only produced in flood season Not a continuous water watch for high and low flows From Hydrologic Information Center – April 14, 2006

Why Change Now? Need for continuous water watch Need to collaborate with our partners more Technology advances allow us to provide more useful information Innovate or dissipate

Ensemble Streamflow Prediction River Forecast Centers capture soil moisture using SAC-SMA (Sacramento) hydrologic soil moisture accounting model and capture snow using SNOW-17 model Good estimations of soil moisture and snow pack water contents are critical to accurate hydrology (RFCs) and meteorology and climate (NCEP) forecasts. To get good soil moisture estimations requires good precipitation inputs Two main zones, an upper and lower

Ensemble Streamflow Prediction Manual Calibration Program (MCP) Operational Forecast System (OFS) Ensemble Streamflow Prediction (ESP) MCP ESP OFS

Ensemble Streamflow Prediction Ensemble Streamflow Prediction (ESP) necessary component used to take short range deterministic SAC-SMA model into short term climate predictions of rivers Similar in concept to the ensembling approach used for atmospheric modeling RFC NWSRFS/ESP/Probabilistic The continuous models feed short term deterministic and longer term probabilistic forecast to the Advanced Hydrologic Prediction Service. Advanced Hydrologic Prediction Service

Ensemble Streamflow Prediction Multiple streamflow scenarios with historic meteorological or forecast weather/climatic data Possible scenarios Flow Scenario 2 Scenario 1 Scenario 3 Saved model states reflect current conditions Time So how does the ESP technique work? You begin by having the hydrologic model save the model states at a particular time. By comparing the model results to observed conditions, the model states can be adjusted to reflect the current conditions. Once saved, a model state acts as a starting point for future simulations. Since observed precipitation and temperature data haven’t happened yet, multiple scenarios using historic or forecast data can be used as input to the model. From each set of inputs, a possible streamflow hydrograph can be generated. Taken together, an ensemble of possible hydrographs are produced. Once several scenario hydrographs are calculated, the results can be used to generate probabilistic streamflow values. Results used in statistical analysis to produce forecasts with probabilistic values ©The COMET Program

Ensemble Streamflow Prediction Future Now Past Low chance of this level flow or higher Medium chance of this level flow or higher Flow High chance of this level flow or higher In another example, past observations are use to adjust the hydrologic model. The current time is when model states are saved. The future will use forecast or historic data as input to the model to produce possible hydrographs. Here, a series of hydrograph traces are generated, each based on a particular set of input values. The resulting traces give an idea of the range of possible flows. For this case, because all of the traces are above this point, the probability that this flow will occur is very high. For the this second case, there is a medium chance flows at this level will occur since some of the traces were above and below this point. For the third case, chances of this flow are low, since all of the trances are lower than this particular value. Time ©The COMET Program

Climate Forecasts Within ESP Pre Adjustment Technique Weight/Modify on Input Side 71 72 73 74 75 Post Adjustment Technique Weight On Output Side We can use the pre-adjust technique by modifying the traces based on CPC outlooks before running each trace. The conditional trace versus historical trace. We can also generate all the historical traces and then weight certain years based on things such as ENSO, the post adjust technique.

Climate Forecasts Within ESP Historical MAT and MAP Adjustment System Adjusted Historical MAP and MAT Weather Forecasts Climate Forecasts This is the pre adjust technique where we generate each historical trace and then modify based on HPC 5 day QPF and CPC 30 and 90 day temperature and precipitation outlooks

Climate Forecasts Within ESP Long range seasonal water supply Spring snowmelt volume forecasts Spring snowmelt peaks Minimum flows for navigation, irrigation, environmental, recreation, etc Water Resources Outlooks

Climate Forecasts within ESP 90-day probability of exceedance Blue line is an historical simulation based on climatology Black line is the conditional simulation with CPC inputs Conditional simulation based on CPC inputs yield lower potential for flooding and high flows. This is the result of ESP for AHPS that the NWS currently uses. This is the 90-day probability of exceedance. The historical simulation is in blue. I think of this as the current states plus normal conditions. The black line is the conditional simulation with CPC outlooks. CPC outlooks made this 90-day outlook drier at the high end and wetter at the lower end.

Water Resources Outlooks Uses NWSRFS SAC-SMA and ESP Uses HPC/CPC Outlooks Can generate a whole host of products An experimental product of NOAA/NWS Being develop for the 30 to 90 day period A new continuous water watch product is in development. It is the WRO product for the Ohio Valley by OHRFC using ESP. SERFC is also working on WRO stuff.

Water Resources Outlooks Partner with USGS/USACE Utilize USGS streamflow percentiles Verify product based on USGS 28-day mean flows Experimental has ended, waiting for operational approval GOAL: Slowly expand nationwide

Water Resources Outlooks Based on basins and point forecasts 159 of 266 OHRFC points have 30, 60 and 90 day expected streamflows 20 more USGS points could be used but incomplete data

Water Resources Outlooks 30-day Verification August 2006 through January 2008 POD above normal flows = 0.78 FAR above normal flows = 0.30 POD below normal flows = 0.65 FAR below normal flows = 0.09 Percent of forecast basins in correct category = 78%

Water Resources Outlook Other Approaches Use analog years (year weighting technique in ESP (Post-Adjustment) based on atmospheric and oceanic response (ENSO/NAO etc) Run ESP with CPC outlooks and analog years approach Research on this is being done by OHRFC and hopefully Michigan Tech

Expansion of Climate Products - Examples Probability of reaching flood stage Uses NWSRFS SAC-SMA and ESP Generated at NCRFC for minor, moderate and major flooding An experimental product of NOAA/NWS Being expanded at other RFCs A new continuous water watch product is in development. It is the WRO product for the Ohio Valley by OHRFC using ESP. SERFC is also working on WRO stuff.

Expansion of Climate Products - Examples Link WRO for each of our points to probability function images Allow customers to drill down into the WRO further Allow customers to modify risks based on ENSO as a starting point This work is being driven by NWS Western Region A new continuous water watch product is in development. It is the WRO product for the Ohio Valley by OHRFC using ESP. SERFC is also working on WRO stuff.

Summary Technology (ESP) has advanced to allow subjective text based flood outlooks to be replaced by a more objective based water resources outlook Climate forecasts are integrated into hydrologic forecasts mostly through adjustments to the inputs in the Ensemble Streamflow Prediction Water Resources Outlooks would provide a continuous water watch for streamflows in the 1-90 day period for expected flows Water Resources Outlooks would not only be for high flows but ALL flows

Summary Streamflow categories are based on USGS percentile categories Verification is based on USGS data Designed to promote NWS/USGS/COE and help us and other partners and customers in their missions! The climate products can be used in providing necessary information on flood and drought potential during the coming months.