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A guide to grid-based products and services from the National Weather Service
What is IFPS?

How the forecast database grids are created

The advantages of a digital forecast database

What is NDFD?

New Forecast Products

The future of IFPS


What is IFPS?

The Interactive Forecast Preparation System (IFPS), is a software suite that the National Weather Service (NWS) began using operationally in 2002. IFPS represents a substantial leap forward in the ability of the NWS to provide forecast information to its customers and partners in a digital age.  In the past, weather information has been disseminated from the NWS primarily through text based products and services. IFPS provides not only for preparation of familiar text based products, but also creates in digital (i.e. numerical) form a database from which a wide range of new graphical and digital forecast products can be generated. The real advantage of IFPS then is in the power of the digital database to provide a greater amount of forecast and weather information in more useful forms.

NWS meteorologist no longer need to manually type long text-based forecast products for specific user communities.  With IFPS, forecasters use a new interactive process to prepare their forecasts, storing meteorological fields in a common digital database.  The database then becomes part of the National Digital Forecast Database (NDFD) which serves as the foundation for countless products and services.

Currently, the NDFD digital database includes individual forecast grids for the following weather elements:

  • Maximum temperature
  • Minimum temperature
  • Probability of precipitation (POP12)
  • Weather
  • Sky cover
  • Wind direction and speed
  • Significant wave height
  • Temperature
  • Dewpoint
  • Precipitation amount
  • Snow amount

While many of the forecast grids are still considered experimental, a limited set have been made official and available through the NDFD, with the addition of more official elements planned in the near future. 


  How are the forecast database grids created?

Meteorologists at each National Weather Service office first import digital computer model and sensible weather data into a Graphical Forecast Editor (GFE). Then, using advanced tools and techniques within the GFE, the forecaster interactively manipulates the digital data for each forecast element or grid. Each point on a grid represents a separate place and time in the forecast period. Using the GFE, meteorologists assign a value to every grid point for each different weather element, and for each time in the forecast period. Each forecast point has a resolution of 5 km, and will soon be upgraded to a higher resolution of 2.5 km.

Example of a 5 km grid point. Using IFPS, NWS forecasters now create forecasts for each 5 km grid point in the U.S.

The tools used to edit the grids are becoming increasingly sophisticated and account for terrain and elevation changes, climatological data, and even diurnal variations for every grid point in the forecast area. A forecaster will create one forecast grid for each of the separate weather elements (temperature, sky cover, etc...). When the grid editing is completed, the weather element grids are stored and transmitted to the NDFD. Various computer programs then use the digital (gridded) database to generate a wide range of text and graphical forecast products. 


What are the advantages of a digital forecast database?

Instead of a limited set of text based forecasts, the digital forecast database itself is offered as a NWS product.  This advantage to NWS customers and partners is extensive. The digital database increases detail in both time and space, provides a greater amount of forecast information, and has the flexibility from which to create a wide range of customized text, graphical and image products.

To illustrate the advantages, we can look at a text product widely distributed by the NWS, the Zone Forecast Product (ZFP).  The ZFP is issued by all NWS offices and by definition is a text based product that is used to explicitly state the weather forecast for each "zone" within a specified forecast area.  The "zone" can encompass a fairly large geographic area necessitating generalized wording at times.  In contrast,  the new digital database provides detailed hourly forecasts for any 5 km grid point in the US and its territories. This means that, utilizing the database, users can generate a forecast of desired weather parameters tailored to their individual needs and location. 

The difference appears very dramatic when we compare the two products in the chart below.  In the zone forecast product, the entire Las Vegas valley is grouped into one forecast "zone". By comparison, the new gridded database contains around 150 unique forecast points for the Las Vegas valley!

Information provided in the forecast for the Las Vegas Valley in a 24 hour period
 Zone Forecast ProductGridded Database (5 km resolution)
Unique Forecast Points1 (McCarran Intl' Airport)about 150
Forecast Weather Elements815
Pieces of Information provided 8-12over 18,000

As you can see the above chart and from the images below, the amount of forecast data now has increased significantly!

NWS Las Vegas Forecast zones. In the Zone Forecast Product one forecast is issued per zone.

NWS Las Vegas gridded forecast for temperature. Each grid point is at a resolution of 5 KM, providing a much more detailed forecast.

There are countless applications for a national digital forecast database. With the advent of graphical products, users can now look at visual displays of probability. The digital data has allowed people to begin generating their own user-specific forecasts on the internet. Private forecasters can download the forecast grids and tailor them to their own needs. Emergency managers can now look at graphical forecasts and determine what and where the greatest weather threat to their responsibility area will be. The new database has already allowed the NWS to begin developing new forecast products such as the State Forecast Table (SFT) and the Point Forecast Matrices (PFM). Imagine, one day soon, you go to use online mapping software and it provides you with a weather forecast for specific points and times along your route!

What is NDFD?

Each local NWS forecast office generates a complete digital database (grids) for their area of responsibility. Each local office's set of grids is then collected and merged into one seemless National Digital Forecast Database (NDFD). To ensure consistency and quality along forecast office boundaries, weather elements are coordinated between offices using graphical methods, computer "instant" messaging, and conference calls.  The NDFD database is made available to all customers and partners (public and private) who can then create a wide range of text, graphic, and image products of their own. Any individual user with a computer and access to the internet can download information from the NDFD to suit his or her needs. In the future, watch and warning information will be added to the NDFD.

View national forecast graphics

Download data files

New Forecast Products

The increased amount of information available in the digital database has allowed new text, graphical, and web-interactive products to be developed. Until the grids in the database become official, most of the following products should be considered experimental and may not agree with official public forecast products (ZFP).

Text Products

Tabular State Forecast Product (SFT) - 7 day tabular forecast of max temperature, min temperature, weather, and probability of precipitation for select cities in the forecast area. Each period is from 6 AM to 6 PM that day.

Point Forecast Matrices (PFM) - Highly detailed point forecast of weather elements displayed in a matrix format. This format is useful for quick scanning and is easily decodable by computers. Forecasts for included weather elements are at 3-hour, 6-hour, and/or 12-hour time intervals through day 7. A PDF guide to using the PFM is available here.

Fire Weather Point Forecast Matrices (FWP) - This product is similar to the PFM, but is geared towards our fire weather customers. Click on the map to get a point forecast for selected RAWS sites within the WFO Las Vegas forecast area.

Graphical Products

Flash Flood Potential Index - This official seasonal product provides users in the WFO Las Vegas warning area with a graphical representation of where the greatest threat for flash flooding will be, and an index of how high the expected threat is for the next three days. The Flash Flood Potential Index is typically available from June through mid-September.

Red Flag Potential Index - This official product uses the forecast wind and relative humidity grids to create a new grid representing the potential that a Red Flag Warning will be needed. The purpose of this product is to provide land management agencies with a graphical image of where the worst fire weather conditions are expected for forecast days two through four.

Dry Lightning Potential Index - This experimental product provides fire weather customers with a graphical representation of where the greatest threat for dry lightning exists during forecast days one through three. The Dry Lightning Potential Index is a seasonal product, and is typically available from June through mid-September.
Flash Flood Potential Index (FFPI)Red Flag Potential Index (RFPI) 

Web-Interactive Products

User-Specific Forecasts - This feature allows anyone with internet access to generate a detailed forecast for a specific location (5 km resolution). The user chooses the number of days the forecast goes out, the forecast interval in hours, and in what format they would like the data displayed.

Weather Planner - This application is designed to generate a quick preliminary planning forecast for parameters and thresholds defined by the user. The output is a color-coded graph representing average conditions in a 5 km grid box nearest the submitted lat/lon point. Parameters include temperature, relative humidity, wind speed, dewpoint, and precipitation.

The future of IFPS

Data from the NDFD will become even more useful as the resolution and the quality of the forecast data increases. The digital database will drive the future of all weather products and services, both from the National Weather Service and from the private sector. An unlimited amount of products and services, including text, graphical, and web-interactive forecasts, will become available. Private companies will be able to use the database to provide high-quality, user-specific products to their customers. Anyone with a home computer and internet access will be able to download the forecast database and generate a forecast that suits their specific needs and location.

Digital data will allow public and private users to access products and services through not only the internet, but through a wide range of electronic devices that are quickly becoming more integrated into each of our daily lives. These devices include cell phones, PDA's, and TV's. The applications for the digital database are literally endless! 

US Dept of Commerce
National Oceanic and Atmospheric Administration
National Weather Service
Las Vegas Weather Forecast Office
7851 S Dean Martin Dr.
Las Vegas, NV 89139-6628

Tel: (702) 263-9744

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