Translating Advances in Numerical Weather Prediction into Official

Translating Advances in Numerical Weather Prediction into Official NWS Forecasts David P. Ruth Meteorological Development Laboratory Symposium on the 50 th Anniversary of Operational NWP June 17, 2004

Coming of the Digital Age for Official NWS Forecasts • Operational Numerical Models • Model Output Statistics (MOS) • Interactive Forecast Preparation System (IFPS) Symposium 50 th Anniversary Operational NWP

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 Symposium 50 th Anniversary Operational NWP

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 Symposium 50 th Anniversary Operational NWP

Approaches to Forecaster Interaction • Matrix Editing – Interactive Computer Worded Forecast (USA) – SCRIBE (Canada) • Grid Editing – – Graphical Forecast Editor (USA) Ri. PP (Sweden) • Object Editing – Forecast Production Assistant (Canada) • Interactive Model Interpretation – Slider Bars (USA) • 4 D Field Modification – Horace (UKMET) Symposium 50 th Anniversary Operational NWP

Symposium 50 th Anniversary Operational NWP

Symposium 50 th Anniversary Operational NWP

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 Symposium 50 th Anniversary Operational NWP

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 Symposium 50 th Anniversary Operational NWP

Image of NDFD grid Symposium 50 th Anniversary Operational NWP

Image of NDFD grid Symposium 50 th Anniversary Operational NWP

Image of NDFD grid Symposium 50 th Anniversary Operational NWP

Image of NDFD grid Symposium 50 th Anniversary Operational NWP

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 Symposium 50 th Anniversary Operational NWP

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 Symposium 50 th Anniversary Operational NWP

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 3 D grids capable of supporting aviation services Symposium 50 th Anniversary Operational NWP

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 Symposium 50 th Anniversary Operational NWP

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 Symposium 50 th Anniversary Operational NWP

IFPS/NDFD in a nutshell from teletype text… Symposium 50 th Anniversary Operational NWP …to digital data streams