Translating Advances in Numerical Weather Prediction into Official NWS Forecasts

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Translating Advances in Numerical Weather
Prediction into Official NWS Forecasts

• David P. RuthMeteorological Development
  Laboratory
• Symposium on the 50th Anniversary of Operational
  NWPJune 17, 2004

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Coming of the Digital Age for Official NWS
Forecasts

• Operational Numerical Models
• Model Output Statistics (MOS)
• Interactive Forecast Preparation System (IFPS)

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Benefits of Interactive Forecast Preparation

• Maximizes human contribution to forecast process
• Provides more forecast detail in time and space
• Enables more effective communication with users
  (e.g., graphics)
• Increases the usefulness of NWS forecasts to
  customers and partners

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How does IFPS work?

• A 7-day digital forecast database is established
  at each WFO
• Forecasters interactively modify the contents of
  the database according to the latest observations
  and model guidance
• NWS text, tabular, voice, and graphical products
  are generated from the database
• The database itself is provided as an NWS product
  to customers and partners

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Approaches to Forecaster Interaction

• Matrix Editing
• Interactive Computer Worded Forecast (USA)
• SCRIBE (Canada)
• Grid Editing
• Graphical Forecast Editor (USA)
• RiPP (Sweden)
• Object Editing
• Forecast Production Assistant (Canada)
• Interactive Model Interpretation
• Slider Bars (USA)
• 4D Field Modification
• Horace (UKMET)

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NDFD Definition

• Contains a seamless mosaic of NWS digital
  forecasts
• Is available to all users and partners public
  and private
• Allows users and partners to create wide range of
  text, graphic, and image products

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NDFD Benefits

• Provides weather information to drive custom
  applications developed by private sector
• - Decision support systems that fit the forecast
  to the problem
• - Weather information along a path
• - Text generation in more than one language
• - Forecasts for vehicles and hand-held devices
  with GPS
• - Controls for smart appliances (e.g., heating,
  cooling, irrigation)
• - Graphics for mass media

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Image of NDFD grid
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Image of NDFD grid
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Image of NDFD grid
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Image of NDFD grid
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Current NDFD experimental elements

• Daytime maximum and nighttime minimum temperature
• Probability of Precipitation (12 hour)
• Significant weather
• Sky cover
• Temperature
• Dewpoint temperature
• Wind direction and speed
• Precipitation amount (QPF)
• Snow amount
• Wave height

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NDFD Resolution

• Spatial resolution
• - 5 km grids for now
• - 2.5 km grids when AWIPS hardware allows
• Temporal resolution
• - 3 hourly for days 1-3
• - 6 hourly for days 4-7
• - as available from CPC beyond day 7
• Update frequency every hour

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NDFD next steps

• Spatial resolution that better resolves complex
  terrain
• Temporal resolution that resolves diurnal cycle
  and can support terminal forecasts
• More frequent than hourly updates
• Additional forecast elements
• Derived parameters, fire weather, marine
• Probabilistic
• Digital forecasts from NCEP service centers
• 3D grids capable of supporting aviation services

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NDFD Value added to Models

• Accuracy at observation points comparable to
  GFS MOS
• Accuracy at gridpoints need Record of
  Analysis
• Variance hourly fields exhibit systematic
  diurnal bias
• Terrain detail apparent for all 7 days
• Spatial consistency problematic across WFO
  borders (esp. hourly fields)
• Timeliness and completeness problematic
• Continuity between issuances presumably better

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A Good Model First-Guess

• Spatial resolution that resolves complex terrain
• Temporal resolution that resolves diurnal cycle
  and can support aviation forecasting
• Predictands that match operational need
• Good continuity from run to run
• Hourly updates based on latest observations
• Quantification of forecast uncertainty

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IFPS/NDFD in a nutshell
to digital data streams
from teletype text