1. By John Metz Warning Coordination Meteorologist WFO Corpus Christi

2. NDFD in a nutshell from teletype text… …to digital data streams

3. Why NDFD? NWS forecasts must keep pace with the digital age. There is still demand for NWS forecasts in text format. NWS has implemented the Interactive Forecast Preparation System (IFPS) which allows forecasters to create the forecast entirely in digital format. The digital database is made available to the public through the NDFD website. Traditional text forecasts now fall out of the digital database.

4. IFPS Grid Editor

5. 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

6. 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 Elements shaded in Yellow = Official

7. 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

8. Temperatures

9. Chance of Rain

10. Precipitation Amount

11. Weather Type

12. Cloud Cover

13. Wind Speed & Direction

14. NDFD elements under development Apparent temperature (Heat index + wind chill) Relative humidity Floating PoP12 index (?) Wind gust speed Max/min relative humidity Lightning Activity Level Mixing height Transport wind direction and speed Haines index Visibility Ice coverage Swell height and direction

15. 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

16. Comparison Traditional Text ForecastNew Digital Text Format

17. NDFD Data Flow AWIPS WAN Grids (Official Forecast) WFO (120+) NCEP (6) NDFD Central Server NCF Forecast grids are encoded in GRIB2 at WFOs and NCEP Grids are decoded and stored to Informix RDBMS NDFD mosaics are generated hourly from WFO grids

18. Timeliness of NDFD Data ThuFri SatSun Mon Tue Wed Thu Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7 Day 8 At 1800 UTC every day, drop Day 1 and add new Day 7 WedThu FriSat Sun Mon Tue Wed Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7 Day 8 NDFD Forecast Mosaics to 168 Hours (7 days)

19. NDFD Data Format Each file contains multiple GRIB2 bulletins for one weather element Each GRIB2 bulletin begins with a unique WMO header Each GRIB2 bulletin contains data for a single weather element for a single valid time Temporal resolution is 3 hours for Days 1-3 and 6 hours for Days 4-7 NDFD data issuance time (YYYYMMDDHH) is encoded in each bulletin

20. NDFD Statistics Tracking Several different types of statistics are tracked on the NDFD (by WFO): Latest receipt times of WFO forecast grids Average forecast update frequency : - daily - weekly - monthly

21. NDFD Statistics Tracking WFO Border Consistency Statistics Assists forecasters in tracking the coordination their of gridded forecasts NDFD processes check (on an hourly basis) the consistency of forecasts across WFO boundaries for an average of adjacent gridpoints Terrain effects are taken into account by including average elevational differences along WFO boundaries Image as well as tabular output is produced as feedback to forecasters

22. NDFD Statistics Tracking NDFD Forecast Verification Another source of feedback to the forecaster to help improve forecast quality Statistics are updated monthly based on previous month’s NDFD forecasts Tracks mean absolute error and forecast bias

23. The End John.metz@noaa.gov 361-299-1354 www.weather.gov www.nws.noaa.gov/ndfd/