by john metz warning coordination meteorologist wfo corpus christi
TRANSCRIPT
By John MetzWarning Coordination Meteorologist
WFO Corpus Christi
NDFD in a nutshell
from teletype text… …to digital data streams
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.
IFPS Grid Editor
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
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
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
Temperatures
Chance of Rain
Precipitation Amount
Weather Type
Cloud Cover
Wind Speed & Direction
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
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
Comparison
Traditional Text Forecast New Digital Text Format
NDFD Data Flow
AWIPS WAN
Grids (Official Forecast)WFO(120+)
NCEP(6)
NDFDCentralServer
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
Timeliness of NDFD Data
ThuThu FriFri SatSat SunSun MonMon TueTue WedWed ThuThu
Day 1Day 1 Day 2Day 2 Day 3Day 3 Day 4Day 4 Day 5Day 5 Day 6Day 6 Day 7Day 7 Day 8Day 8
At 1800 UTC every day, drop Day 1 and add new Day 7 At 1800 UTC every day, drop Day 1 and add new Day 7
WedWed ThuThu FriFri SatSat SunSun MonMon TueTue WedWed
Day 1Day 1 Day 2Day 2 Day 3Day 3 Day 4Day 4 Day 5Day 5 Day 6Day 6 Day 7Day 7 Day 8Day 8
NDFD Forecast Mosaics to 168 Hours (7 days)NDFD Forecast Mosaics to 168 Hours (7 days)
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
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
NDFD Statistics TrackingWFO 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
NDFD Statistics TrackingNDFD 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
