Flash Flood Monitoring and Prediction

Current Operational Capabilities, Issues and Perspectives

Britt Westergard, Service HydrologistWFO Jackson, KY

Q2 Workshop – June 28, 2005

Slide courtesy of Mary Mullusky

Data and Decision Assistance Tools

• Forecasters integrate observed and forecast information to assess the flash flood threat

• Data sources include radar data and in-situ precipitation gages (e.g., ASOS and ALERT)

• Decision assistance tools facilitate analysis of large and diverse data sets to identify conditions conducive to flash flooding

• The Flash Flood Monitoring and Prediction (FFMP) Application is a new NWS radar-based Advanced Hydrologic Prediction Service (AHPS) decision assistance application

Slide courtesy of Mary Mullusky

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

Slide courtesy of Mary Mullusky

FFMPAvailable Data and Algorithms

Slide courtesy of Mary Mullusky

FFMP: Forecaster InterfaceCounty Precipitation Accumulation

• Displays precipitation for the basin in the county that has highest accumulation

FFMP 1.0 Hour Basin Avg Precip

Slide courtesy of Mary Mullusky

FFMP: Forecaster InterfaceBasin Precipitation Accumulation

• Displays basin precipitation within the selected county FFMP 1.0 Hour Basin Avg Precip

Current Operational Capabilities Brand New Functionality

Monitor Small

Streams on Large Scale

Current Operational Capabilities Brand New Functionality

Monitor Basins of Various

Sizes on a Large Scale

Image courtesy of WFO Springfield, MO

Current Operational Capabilities The Field Perspective

• “The best flash flood tool that has ever been implemented.”

• Streamlink files (pseudo-streams) to visualize water routing

• Forced Flash Flood Guidance

• Provide basin names in Flash Flood Warnings and Statements – customers more likely to take action

Current Operational Issues

Three components to FFMP:

• Quantitative Precipitation Estimate (QPE)

• Flash Flood Guidance (FFG)

• Quantitative Precipitation Forecast (QPF)

Current Operational Issues– QPE –

• Current operational methods for compensating for radar QPE inaccuracies– Basin trends chart with gage data– Incorporate MPE bias into radar precipitation

processing– “Ratio of the day” approach

• No radar, no FFMP – investigate additional QPE sources (satellite?)

Current Operational Capabilities The Field Perspective

Basin Trend Graph

Current Operational Issues– FFG –

• Local research into baseline FFG versus precipitation (ratio) – thresholds for issuing particular products (USS vs FFW)

• Improved FFG from RFCs – local coordination essential

• Other guidance solutions beyond FFG…?

Current Operational Issues– Current QPF –

• Current focus is on Flash Flood Monitoring• Very short term QPF (1/3/6 hours) is

essential to the Prediction in FFMP• Short-term QPF currently available in

FFMP is SCAN 1-hour QPF – not widely used, documentation issues

• Also more generalized QPF available (RFC 6 hour QPF – not ideal resolution for flash flood prediction)

Current Operational Issues– Future QPF –

• Improved or additional sources of very short term QPF needed

• Software ideally would add QPF and QPE to give a predicted ratio – significant lead time increases

• Forecaster knowledge of algorithms used is important for confidence in QPF

Current Operational Issues– The Hydrology Side –

• Ability to track or route water (FFMP may not be the venue for this)

• Basin customization – local knowledge increases utility of software

• Improved maps of different basin aggregation levels to assist in watershed visualization

So, what’s your point?

• The field’s need for improved QPE and very short term QPF is apparent.

• The platform to implement these improvements in a way useful to the WFOs already exists – FFMP!