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Status of NDFD Elements as of
Nov 5, 2013

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General Information

You can access NDFD elements via file transfer protocol (ftp), http, eXtensible Markup Language (XML), or web browser. Links to the data, supporting information and software are listed below:

Description of NDFD Database Contents

Elements

Currently, the NDFD contains data representing the following weather elements. More elements will be added as development of the NDFD progresses. NDFD data are available for projections (as described in the table below) at the following Coordinated Universal Times (UTC): 0000, 0300, 0600, 0900, 1200, 1500, 1800, 2100.

Elements

No. of Grids

Projections

12-hour Probability of Precipitation (PoP12)

13-15

Every 12 hours, out to 168 hours

Apparent Temperature

33-41

Every 3 hours out to 72 hours;
every 6 hours out to 168 hours

Dew Point

33-41

Every 3 hours out to 72 hours;
every 6 hours out to 168 hours

Hazards 59-82 Every hour, out to 72 hours;
every 6 hours out to 120 hours

Maximum Temperature

7-8

Every 24 hours, out to 168 hours

Minimum Temperature

6-7

Every 24 hours, out to 168 hours

Quantitative Precipitation Amount

9-13

Every 6 hours out to 72 hours

Relative Humidity

33-41

Every 3 hours out to 72 hours;
every 6 hours out to 168 hours

Significant Wave Height

17-21

Every 6 hours out to 120 hours

Sky Cover

33-41

Every 3 hours out to 72 hours;
every 6 hours out to 168 hours

Snow Amount

5-9

Every 6 hours out to 48 hours

Temperature

33-41

Every 3 hours out to 72 hours;
every 6 hours out to 168 hours

Weather

33-41

Every 3 hours out to 72 hours;
every 6 hours out to 168 hours

Wind Direction

33-41

Every 3 hours out to 72 hours;
every 6 hours out to 168 hours

Wind Gust

17-25

Every 3 hours out to 72 hours

Wind Speed

33-41

Every 3 hours out to 72 hours;
every 6 hours out to 168 hours

Climate Outlook Probabilities - 12 separate elements:

8- to 14-day Avg Temperature Above Normal

1

14 days (issued once daily)

8- to 14-day Avg Temperature Below Normal

1

14 days (issued once daily)

8- to 14-day Total Precipitation Above Median

1

14 days (issued once daily)

8- to 14-day Total Precipitation Below Median

1

14 days (issued once daily)

One-month Avg Temperature Above Normal

1

45 days (issued twice on 3rd Thurs of month)

One-month Avg Temperature Below Normal

1

45 days (issued twice 3rd Thurs each month)

One-month Total Precipitation Above Median

1

45 days (issued twice 3rd Thurs each month)

One-month Total Precipitation Below Median

1

45 days (issued twice 3rd Thurs each month)

Three-month Avg Temperature Above Normal

13*

375 days (issued twice 3rd Thurs each month)

Three-month Avg Temperature Below Normal

13*

375 days (issued twice 3rd Thurs each month)

Three-month Total Precipitation Above Median

13*

375 days (issued twice 3rd Thurs each month)

Three-month Total Precipitation Below Median

13*

375 days (issued twice 3rd Thurs each month)

Convective Outlook Hazard Probabilities - 9 separate elements:

Convective Hazard Outlook

3

Days 1, 2, and 3

Probability of Tornadoes

1

Day 1

Probability of Hail

1

Day 1

Probability of Damaging Thunderstorm Winds

1

Day 1

Probability of Extreme Tornadoes

1

Day 1

Probability of Extreme Hail

1

Day 1

Probability of Extreme Thunderstorm Winds

1

Day 1

Total Probability of Severe Thunderstorms

2

Days 2 and 3

Total Probability of Extreme Severe Thunderstorms

2

Days 2 and 3

Probabilistic Tropical Cyclone Surface Wind Speeds - 6 separate elements:

>34kts (incremental)

17-21

Every 6 hours out to 120 hours

>34kts (cumulative)

17-21

Every 6 hours out to 120 hours

>50kts (incremental)

17-21

Every 6 hours out to 120 hours

>50kts (cumulative)

17-21

Every 6 hours out to 120 hours

>64kts (incremental)

17-21

Every 6 hours out to 120 hours

>64kts (cumulative)

17-21

Every 6 hours out to 120 hours

* 13 issuances for months 1 - 3, months 2 - 4, months 3 - 5, ..., up to months 13 -15

List of Element Definitions

NDFD Communication Identifier Reference

Geographic Coverage

The elements in NDFD are available for the CONUS and 16 pre-defined CONUS subsectors. A subset of NDFD elements is available for Puerto Rico/the Virgin Islands, Hawaii, Guam, and Alaska. Refer to the NDFD Element Status Table for the specific elements available for each domain.

Grid Resolution

Grids for the CONUS are currently available from NDFD at 5 kilometer spatial resolution. The spatial resolution for the grids for Hawaii and Guam is 2.5 kilometers; for Puerto Rico/the Virgin Islands is 1.25 kilometers; for Alaska, 6 kilometers. For the North Pacific Ocean Domain the spatial resolution is 10 km.

These spatial resolutions are nominal; the actual spacing in kilometers varies by latitude. The exact specifications for NDFD can be found in the GRIB2 Encoding Details for the National Digital Forecast Database and the NDFD Spatial Reference System web page.

The temporal resolution of NDFD grids varies by element; see the table of NDFD elements for specifics.

NWS plans to increase both spatial and temporal resolution in the future.

Customer Support

For real-time customer support, contact the NWS Telecommunications Gateway at 301-713-0902


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Questions? Comments? nws.ndfd@noaa.gov
Last Updated: December 5, 2013

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