Improving Flash Flood Services

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Improving Flash Flood Services

• Mary Mullusky
• National RFC Hydrologic Services Program Leader
• Hydrologic Services Division
• Office of Climate, Water and Weather Services

National Hydrologic Program Managers
Conference July 10, 2007
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Outline
Improving Flash Flood Services Outline

• AHPS Flash Flood Services Theme Team
• Flash Flood Services Projects
• QPE/QPF Improvements
• FFG Improvements
• FFMP Improvements
• Site Specific Hydrologic Predictor Improvements
• Dam Break Tools

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Outline
Improving Flash Flood Services AHPS Flash Flood
Services Theme Team

• FY07 Team Process
• Team evaluated over 20 AHPS flash flood projects
• Team prioritized projects and created funding
  proposals
• Team leader presented proposals to the AHPS
  Program Coordinator and the AHPS Review Committee
  
• Hydrology Program Manager has final authority

• Team Members
• Mary Mullusky (NWSH/HSD)
• Bill Lawrence (ABRFC)
• Peter Ahnert (MARFC)
• Greg Smith (CBRFC)
• Brian McInereny (WFO Salt Lake City)
• John Woynick (WFO Topeka)
• Frank Bell (WGRFC)
• George McKillop (ERH/HSD)
• Ernie Wells will be FY2008 team leader

• Technical Representatives
• David Kitzmiller (NWSH/OHD)
• Seann Reed (NWSH/OHD)
• Ed Danaher (NCEP/HPC)
• Mark Glaudemans (NWSH/OHD)
• Mark Fresch (NWS/OHD)
• Reggina Cabrera (NWS/OHD)
• Tom Donaldson (NWSH/HSD)
• Tom Filiaggi (NWSH/MDL)
• Ken Howard (NSSL)

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Outline
Improving Flash Flood Services QPE/QPF
Improvements

• Super Resolution (Build 10, AWIPS OB 8.2)

• increased reflectivity data resolution from 1 km
  to ¼ km
• increase azimuthal resolution of reflectivity,
  velocity and spectrum width from 1 to 0.5
• extend the range of Doppler data from 230 km to
  300 km
• Derived products will not use super resolution in
  this build
• Nexrad Product Improvement recently tasked OHD to
  compare derived precipitation products from super
  resolution and standard resolution

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Outline
Improving Flash Flood Services QPE/QPF
Improvements

• Dual Polarization (Build 11, AWIPS OB8.3 2 year
  deployment)

• Improved precipitation estimation, Improved data
  quality, improved hail identification, and
  hydrometeor classification
• 1 degree by ¼ km data for base products and most
  derived products
• DHR will still exist (for now)
• DPR (Digital Precipitation Rate) is the dual
  polarization replacement product for DHR
• FFMP Advanced Design (AWIPS OB 8.3) should be
  able to ingest DPR for monitoring and display

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Outline
Improving Flash Flood Services QPE/QPF
Improvements

• Enhanced Multisensor Precipitation Estimation
  (EMPE) (AWIPS OB8.3)

• High resolution rain rate and precipitation
  accumulation grids
• spatial resolution 1/4 HRAP mesh length (1x1
  km)
• Update frequency configurable up to 5 minute
  intervals
• DHR used to create radar rain rate estimates
• Gages are NOT used in this version of EMPE,
  however the MPE gage-radar bias table can be used
  in rain rate and accumulation estimation
• Dual Polarization DPR NOT used in this version of
  EMPE

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Outline
Improving Flash Flood Services QPE/QPF
Improvements

• Multisensor Precipitation Nowcaster (MPN) (AWIPS
  OB9.0)
• An extrapolative forecast of the reflectivity
  field valid for the next hour, updated every 15
  minutes on an HRAP grid. Additional fields for
  AWIPS display include
• 1-hour radar precipitation accumulation forecast
  (with and without bias correction)
• Instantaneous rain rate forecasts at 15 minute
  intervals out through 1-hour (with and without
  bias correction)
• RFC MPE Mean Field Bias to WFO (AWIPS OB8.2)
• WFO operators can select which RFC bias message
  to receive and which bias message to send to the
  RPG
• NMQ/Q2 infusion into NCEP (no targeted build)
• Probabilistic QPE (no targeted build)

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Outline
Improving Flash Flood Services FFG Improvements
Length to divide
Slope
OHD RDMS Soil Moisture

• ABRFCs Gridded FFG

Area
Static CN
Gridded Runoff

• Produce a flash flood guidance product at a
  resolution similar in scale to FFMP
• Gridded FFG is derived from HRAP resolution (4km
  x4km) of
• Soil moisture conditions from the Hydrology Lab -
  Research Distributed Hydrologic Model
• Dynamic NRCS Curve Number from soil data and land
  use land cover data and distributed model soil
  moisture conditions
• NRCS Unit Hydrograph model combined with a design
  storm to estimate bankfull flow (Thresh-R)
• Method treats each HRAP grid cell as an
  independent headwater basin

Duration
2-yr, 3-hr DDF
Dynamic NRCS Curve Number
Variable Threshold Runoff
For more details see the Gridded Flash Flood
Guidance topical breakout session
Gridded FFG
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Outline
Improving Flash Flood Services FFG Improvements

• ABRFCs Gridded FFG

Fully Operational Under Development To be
developed In FY07
Status Developing 1, 3, and 6 hour FFG and
Thresh-R
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Outline
Improving Flash Flood Services FFG Improvements

• CBRFCs Flash Flood Potential Index

• Using GIS and digital data of soil type,
  vegetation type and density, slope, and land use
  create a single value index of hydrologic
  response.
• Developed a process to modify FFPI with wildfire
  burn severity information.

Land Use
Soil type
Vegetation type and density
Wildfire
Slopes
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Outline
Improving Flash Flood Services FFG Improvements

• CBRFCs Flash Flood Potential Index

• Current Status
• Prototypes Completed
• To be completed in FY07
• Future development
• Incorporate dynamic soil moisture component
• Derive FFG from relationships between the FFPI
  and historical event data.

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Outline
Improving Flash Flood Services FFG Improvements

• Distributed Hydrologic Model Threshold
  Frequency Methodology

Historical
Real-time

• Run distributed hydrologic model in historical
  mode to create a simulated peaks distribution for
  each grid cell
• Run the distributed hydrologic model in real-time
  to create a maximum forecast peak for each grid
  cell
• Use a statistical post-processor to create
  forecast frequencies for each grid cell from the
  maximum forecast peak and the simulated peaks
  distribution
• Compare forecast frequencies with frequency
  threshold from local/regional knowledge

Distributed hydrologic model
Distributed hydrologic model
Initial hydro model states
Simulated peaks distribution (Qsp) (unique for
each cell)
Max forecast peaks
Probability
Statistical Post-processor
Flow (cms)
Local/regional knowledge
Compare
Frequency thresholds
Forecast frequencies
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Outline
Improving Flash Flood Services FFG Improvements

• Distributed Hydrologic Model Threshold
  Frequency Method

• Benefits
• Relative measure (easier to understand than CMS)
• Inherent bias correction
• Local information often available to help define
  thresholds (e.g. engineering design,
  geomorphology studies)
• Can be used when bankfull flow is not
  meaningful (e.g. slot canyons)
• Limitation
• Required data may not be available everywhere
• Current Status
• Developing prototype for flash flood prone
  Baltimore area

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Outline
Improving Flash Flood Services Summary of FFG
Improvements
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Outline
Improving Flash Flood Services FFMP Improvements
AWIPS OB7.2
Zoom X
X
Emphasized Forced Flash Flood Guidance
Virtual Gage Basins
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Outline
Improving Flash Flood Services FFMP Improvements
AWIPS OB7.2
Basin Trace Fix consistent hatching
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Outline
Improving Flash Flood Services FFMP Improvements
AWIPS OB8.1
Basin Trace Fix editable
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Outline
Improving Flash Flood Services FFMP Improvements
AWIPS OB8.3
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Outline
Improving Flash Flood Services FFMP Improvements
AWIPS OB8.3

• Precipitation Sources
• DHR
• DPR
• EMPE
• NMQ (in prototype)
• SCAN QPF
• MPN (w/ OB9.0)

• Join duration from different sources
• For example a 3 hour duration derived from 1 hour
  MPN and 2 hours EMPE

• FFG Sources
• Legacy FFG
• Gridded FFG
• Debris Flow Guidance

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Outline
Improving Flash Flood Services WarnGen
OB 8.2 ?

• FFMP Basin names in WarnGen

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Outline
Improving Flash Flood Services Site Specific
Hydrologic Predictor Improvements OB8.2
Precip visualization and save/reload
Action, minor, moderate, and major stages
displayed (if defined)
Select alternate UHG (if defined)
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Outline
Improving Flash Flood Services Site Specific
Hydrologic Predictor Improvements

• Future development (targeted for OB9 Gulf
  offices may see earlier)
• Simplified Routing Variable Lag and Variable K
  routing
• A separate variational data assimilation program
  to update the states of the SSHP SAC-SMA rainfall
  runoff model

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Outline
Improving Flash Flood Services Dam Break Tools

• Goal Review the database and existing tools for
  simplified dam break
• Status Project delayed due to staff shortages in
  the Hydraulics Group of OHD

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Improving Flash Flood Services

• Thank you!
• Any Questions?

National Hydrologic Program Managers
Conference July 10, 2007