Flash Flood Prediction Working Group Q2 Workshop June 28-30, 2005

 Provide river and flood forecasts and warnings for the protection of lives and property.  Provide basic hydrologic forecast information for the nation’s environmental and economic well being. Mission of NWS Hydrologic Services Program

Current Flash Flood Services  Primary WFO Products and Information Flash Flood Watch Flash Flood Watch Flash Flood Warning Flash Flood Warning NATIONAL WEATHER SERVICE INSTRUCTION WEATHER FORECAST OFFICE HYDROLOGIC PRODUCTS SPECIFICATIONhttp:// BULLETIN - IMMEDIATE BROADCAST REQUESTED FLOOD WATCH NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 930 AM PST WED FEB A FLASH FLOOD WATCH CONTINUES UNTIL 1100 PM FOR THE BURN AREAS OF VENTURA AND LOS ANGELES COUNTIES... A FLASH FLOOD WATCH MEANS THAT FLASH FLOODING IS POSSIBLE... BUT NOT IMMINENT...IN THE WATCH AREA. PEOPLE IN THESE AREAS SHOULD STAY ABREAST OF THE LATEST DEVELOPMENTS AND BE PREPARED TO TAKE IMMEDIATE ACTION IF A WARNING IS ISSUED OR FLOODING IS ENCOUNTERED.

Current Flash Flood Services  Flash Flood Watch Inform the public of hydrometeorological conditions which may cause flooding when the flooding is neither certain nor imminent Inform the public of hydrometeorological conditions which may cause flooding when the flooding is neither certain nor imminent Provide advance notice on flooding possible within 36 hours Provide advance notice on flooding possible within 36 hours Enable decision makers to monitor conditions more closely and elevate flood mitigation resources to a higher state of readiness Enable decision makers to monitor conditions more closely and elevate flood mitigation resources to a higher state of readiness

Current Flash Flood Services  Flash Flood Warning Issue when flooding is imminent Issue when flooding is imminent Provide advance notification of short-fused flood events which require immediate action to protect lives and property Provide advance notification of short-fused flood events which require immediate action to protect lives and property Allow customers and partners to take immediate mitigation actions such as evacuation to higher ground Allow customers and partners to take immediate mitigation actions such as evacuation to higher ground

Current Flash Flood Services  Product Dissemination Internet ( Internet ( NOAA Weather Radio NOAA Weather Radio Emergency Managers Weather Information Network Emergency Managers Weather Information Network NOAA Weather Wire Service NOAA Weather Wire Service Family of Services Family of Services NOAAPORT NOAAPORT EAS EAS

Verification  Flash Flood Warning verification statistics are based on product issuance information and confirmation of actual flash floods by the local WFOs. Flash Flood Warning Lead Time Flash Flood Warning Lead Time Flash Flood Warning Accuracy Flash Flood Warning Accuracy FY03 Actual FY04 Actual FY05 Actual (Oct –Mar) FY05 Goal FY2012 Goal (FY08 PBA) Lead Time (minutes) *51 Accuracy (%) 89 91

Impact of Technology, Training, Expanding Outreach and Dissemination on Flash Flood Services NEXRADImplementation Where will the next improvement come from? FFMPImplementation

Data and Decision Assistance Tools  Forecasters integrate observed and forecast information to assess the threat of flash flooding  Data sources include radar data and in-situ precipitation gages and FFG (e.g., ASOS and ALERT)  Decision assistance tools facilitate analysis of large and diverse data sets to identify conditions conducive to flash flooding

Current Operational Practices for Predicting Flash Flood  FFMP The Flash Flood Monitoring and Prediction (FFMP) Application is a new NWS radar-based Advanced Hydrologic Prediction Service (AHPS) decision assistance application The Flash Flood Monitoring and Prediction (FFMP) Application is a new NWS radar-based Advanced Hydrologic Prediction Service (AHPS) decision assistance application  Site Specific  DamCREST  Traditional Methods

FFMP  Continuous monitoring of rainfall rate and accumulation with comparison to flash flood guidance for high resolution stream basins  Automated alerts when a dangerous flash flood situation may be developing on a given stream or catchment  Released to WFOs in AWIPS in 2002

FFMP: Software/Hardware  FFMP is a baseline application that runs on local AWIPS processors. It is embedded in the AWIPS D2D Graphical User Interface. /FFMP

FFMP Available Data and Algorithms

2130 – 2135 UTC Rainfall (in/hr) Grid size 1 o x 1km FFMP Available data and algorithms Watershed Boundary

FFMP: Forecaster Interface County Precipitation Accumulation  Displays precipitation for the basin in the county that has highest accumulation FFMP 1.0 Hour Basin Avg Precip

FFMP: Forecaster Interface Basin Precipitation Accumulation  Displays basin precipitation within the selected county FFMP 1.0 Hour Basin Avg Precip

FFMP: Product Generation  WarnGen is used with FFMP to issue Flash Flood Warnings

Outstanding Science and Research to Operations Issues  Radar data availability is limited especially in the Western United States  WFOs served by more than one radar must run an instance of FFMP for each radar  Limitations of radar Uses raw radar data precipitation estimates – no bias adjusting Uses raw radar data precipitation estimates – no bias adjusting Radar bins increase in size and altitude with distance from the radar Radar bins increase in size and altitude with distance from the radar Brightband contamination Brightband contamination Hail contamination Hail contamination Inaccurate Z/R relationships Inaccurate Z/R relationships  Limitations of FFG FFG is developed from hydrologic models calibrated for river forecasting of larger basins. The calibrations are not necessarily scalable for the basins associated with flash floods. FFG is developed from hydrologic models calibrated for river forecasting of larger basins. The calibrations are not necessarily scalable for the basins associated with flash floods. Discrepancies across RFC boundaries Discrepancies across RFC boundaries Not appropriate for regions where the dominant flash flood factors are rainfall intensity and terrain Not appropriate for regions where the dominant flash flood factors are rainfall intensity and terrain

Emerging Scientific Solutions for Predicting Flash Flood  Improved radar estimates of precipitation Probabilistic QPE from Radar Probabilistic QPE from Radar Dual polarization radar precipitation estimates Dual polarization radar precipitation estimates Precipitation estimation from TDWR Precipitation estimation from TDWR  Improved Multi-sensor Precipitation estimates  Improved Short Range QPF  FFMP improvements  Flash Flood Potential Index  Statistical Distributed Modeling  Distributed Modeling

Emerging Scientific Solutions FFMP Improvements  Current research to operation efforts Generate regionally-mosaicked, multi- sensor precipitation estimates every volume scan displayed on a 1 km grid for the time scales used in FFMP (0.5 hour, 1 hour, 2 hour and 3 hour) Generate regionally-mosaicked, multi- sensor precipitation estimates every volume scan displayed on a 1 km grid for the time scales used in FFMP (0.5 hour, 1 hour, 2 hour and 3 hour) Ingest gridded precipitation estimates (NMQ, MPE, Q2, QPF…) into FFMP Ingest gridded precipitation estimates (NMQ, MPE, Q2, QPF…) into FFMP Toggle between multiple QPE inputs Toggle between multiple QPE inputs

Emerging Scientific Solutions FFMP Improvements  Enhanced QPE/QPF Capabilities (NWS Operational Requirements Document - Flash Flood Monitoring and Prediction Fall 2003) If scientific investigation shows that the increased spatial resolution is beneficial to precipitation estimates, then increase the spatial resolution of the multi-sensor precipitation estimates to 0.5 km by 0.5 km. If scientific investigation shows that the increased spatial resolution is beneficial to precipitation estimates, then increase the spatial resolution of the multi-sensor precipitation estimates to 0.5 km by 0.5 km. Increase frequency of integration of satellite QPE into multi-sensor precipitation estimates from every 60 minutes to every 15 minutes Increase frequency of integration of satellite QPE into multi-sensor precipitation estimates from every 60 minutes to every 15 minutes Generate DHR-based rainfall products with a resolution of 0.5 by 0.25 km (ORDA FY08) Generate DHR-based rainfall products with a resolution of 0.5 by 0.25 km (ORDA FY08) Provide capability to display and monitor QPF Provide capability to display and monitor QPF Enhance the rain gauge network data flow from all sources and deliver to AWIPS for use in multi-sensor precipitation estimates and FFMP at 5 minute resolution. Enhance the rain gauge network data flow from all sources and deliver to AWIPS for use in multi-sensor precipitation estimates and FFMP at 5 minute resolution.  Other requirements identified in the ORD include GIS improvements, improvements in FFMP Display methods, and improvements in FFG estimates

obtain raster (gridded) datasets representing the features of interest Utilize GIS tools/methods to develop a single index that represents the a potential for flash flooding (on a relative scale) Emerging Scientific Solutions Flash Flood Potential Index

Gridded –Relative– Flash Flood Potential Emerging Scientific Solutions Flash Flood Potential Index

STATSGO Dominant Soil Texture MLRC Land Use / Land Cover NOAA AVHRR Forest Density Grid USGS DEM (derived % slope Grid – Terrain) Fire Burn Areas / Severity coverage Relative Flash Flood Potential An indication of rapid hydrologic response LowHigh Summarize Grids to Geographic Layer (Basin) FFMP Basins Emerging Scientific Solutions Flash Flood Potential Index

 Currently researching methods to add a soil moisture layer to FFPI to support national implementation. Will need to integrate gridded 1-hour multi- sensor precipitation estimates to estimate soil moisture. Will need to integrate gridded 1-hour multi- sensor precipitation estimates to estimate soil moisture.

Observed Simulated (2) (1) Regional flood threshold estimate (3) Forecasted peak flow Methodology 1. Using observed data for a region, derive a probability distribution describing the chance of exceeding a flood threshold given a computed flow frequency 2. Derive a simulated climatology for each model grid cell Shaded area is probability of exceeding bankfull flow. 3. Given a forecasted flow, derive the probability of exceeding simulated climatology for each model grid cell Emerging Scientific Solutions Statistical Distributed Model

 Precipitation Estimation requirements Initial Proof of Concept with Hourly Stage III products on an HRAP grid. Initial Proof of Concept with Hourly Stage III products on an HRAP grid. Model framework can be used to test precipitation estimates at higher spatial and temporal resolutions Model framework can be used to test precipitation estimates at higher spatial and temporal resolutions Plan to expand approach to ingest 1-hour forecast precipitation grids. Plan to expand approach to ingest 1-hour forecast precipitation grids.

Arkansas R. Red R. Blue R. Emerging Scientific Solutions Distributed Modeling Distributed Model Intercomparison Project

Hydrologic Response at Different Points in the Blue River Basin Emerging Scientific Solutions Distributed Modeling

Application of HL Distributed Model Emerging Scientific Solutions Distributed Modeling

 Precipitation Estimation requirements Hourly Stage III products on an HRAP grid. Hourly Stage III products on an HRAP grid.

Precipitation Requirements for Flash Flood Prediction  Improved quality of precipitation estimates  Accurate high–resolution seamless multi-sensor gridded precipitation estimates  Timely estimates every five minutes as close to real-time (minimize processing, latency, … without degrading quality)  Ingest short-term (0-1 hour) high quality seamless QPF  Carry forward human quality control knowledge interaction to real-time QPE estimates  Improve gauge quality and network  Gap filling mechanisms Satellite estimates Satellite estimates  Hourly updates for soil moisture components

Other Priorities for Flash Flood Prediction  Improved FFG  Societal Impacts and Public Perception  Verification Ground Truth Ground Truth Flash Flood Climatology Flash Flood Climatology  Training  GIS Solutions - Fire scars  Uncertainty  Visualization