Graphical Forecasts for Aviation Tutorial

Graphical Forecasts for Aviation Tutorial

This section provides information on effectively using the Graphical Forecasts for Aviation displays. The following topics are covered:

GFA Display

Graphical Forecasts for Aviation Overview
Figure 1: Graphical Forecasts for Aviation Overview

Forecast and Obs/Warn

The Forecast and Obs/Warn buttons determine the options of preset graphics available to view, shown by the tabs located above the main menu bar. When Forecast is selected (default), the user can then chose to view information related to TAFs, ceiling and visibility, clouds, precipitation, thunderstorms, winds, turbulence, or ice. Data under each tab is available by the hour starting one hour ahead of the current time to fifteen hours in the future.

Forecast Products Tabs
Figure 2: Forecast Products Tabs

When Obs/Warn is selected, the tab group changes, allowing the user to select from METAR, precipitation and weather, ceiling and visibility, PIREP, or radar and satellite. Hourly observations for each tab are available from fourteen hours in the past up to the current time.

Observations & Warnings Products Tabs
Figure 3: Observations & Warnings Products Tabs

Details of the data in each tab option can be found under the Products info page.

Vertical Levels

The level menu only appears when the Icing, Turbulence, Winds, or PIREP tab is selected. For these four options, the user can select a Flight Level in 3000 ft. increments from the surface up to Flight Level (FL) 300, or 30,000 feet MSL. From FL300 to FL480, the user can select an altitude in 6000 ft. increments. For Icing and Winds, the user can also select "SFC" or "MAX." For turbulence, these options change to "Lo" and "Hi" which display the max turbulence below FL180 and above FL180 respectively. Details of the data displayed at each altitude can be found on the Products info page.

Time Slider

The valid time (in UTC) for the data displayed is located in the upper right corner of the graphic. This display will also show how many hours ahead or behind the current time is selected. The user can select up to 15 hours in the future when viewing the Forecast tabs or 14 hours in the past when viewing the Obs/Warn tabs. The hour can be selected by clicking the back or forward arrows or by clicking and dragging the box on the time slider bar at the top of the image. The selected time will be highlighted amber. As the slider is moved forward, the bar will be highlighted in green between the first forecast hour and the selected hour. When moving the slider backward, the bar will be highlighted in red between the current time and the selected hour.

All data are synchronized to the time slider. For example, moving back in time will reset valid times for METARs, SIGMETs, G-AIRMETs, etc. Weather images will also display analyses valid for the new valid time.. The radar loop will reset to show the latest five radar images in a loop terminating in the valid time. Note: Text boxes will need to be re-opened to refresh the data.


The various elements in the legend will change to only show those applicable to the tab the user has selected. The legends are located at the bottom of the display.

Full Screen Mode

The display can be rendered to full screen mode using the full screen button in the upper right part of the display. The menu bar will remain at the top of the screen but the rest of the display will now cover the full screen. Pressing the full screen button again will return the display to normal view. When in full screen mode, a "show legend" button will appear. Clicking on this button will bring the appropriate legends into view.

Panning and Zooming the Map

The map can be panned using the mouse. By clicking the left mouse button in the display area and moving it, the map will pan. Once the mouse button is released, the data will refresh to the new display area. On a tablet, touching the display area and dragging will pan the map.

There are several ways to zoom in and out. The +/- buttons in the upper left corner of the display can be used. Also, if the mouse has a scroll wheel, it can be used to zoom in and out depending on the direction the wheel is moved. On a tablet, pinch zooming is available. Finally, by holding the shift key while pressing the left mouse button, a zoom region can be selected. A red box will display and once the mouse button is released, the closest region to the zoom box will be displayed. Since OpenLayers uses an integral zoom level with each level being twice the magnification, exact zooms are not possible.

Text Data

Additional information can be obtained through pop-up text data boxes for METARs, TAFs, PIREPs, SIGMETs, G-AIRMETS, NWS Warnings, Cloud grid points, and Wind Barbs. Clicking on the observation or polygon will bring up a box with more information including the raw observations. Note: The text must be reselected after changing the valid time in order to refresh.

Map Options

The Map Options button enables the user to adjust how and what information is displayed on the map. Once the settings have been adjusted, they can be saved for future sessions.

GFA Map Options Button
Figure 4: Map Options Button

When the "Map Options" button is clicked a menu opens to the left of the map providing access to additional settings. Note: The button text changes to "Hide Options" when the menu is active. The Map Options can be closed by clicking the "Hide Options" button, clicking any where outside of the map area, or clicking the "Save & Close" button below the options menu.

GFA Map Options Menu
Figure 5: Map Options Menu

Warnings & Advisories

Selecting the first map option item—WARNINGS & ADVISORIES—will expand the menu and allow for the adjustment of SIGMETS, NWS Warnings, Center Weather Advisories, and G-AIRMET settings.

Warnings and Advisories Options
Figure 6: Warnings & Advisories Options

Each overlay can be toggled on and off independently by using the checkboxes preceding the warning/advisory name. The transparency of each product can be modified by adjusting the value of its respective opacity drop-down. Additionally, SIGMET heights can be displayed by checking the "Heights" checkbox.


FORECASTS, the second map options menu item, pemits the user to change the settings for weather grids and symbols as well as TAFs.

GFA Forecasts Options
Figure 7: Forecasts Options

As before, the checkboxes before the terms are used to hide or display them, and the transparency of the Weather Grid overlay can be adjusted by changing the "Opacity" dropdown value.

Both the Weather Symbols and TAFs can have the number and size of icons displayed changed by using the "Show" and "Scale" dropdowns respectively. Moreover, TAFs information can be displayed with either English or Metric values by clicking the "Metric" checkbox.


The third map option button—OBSERVATIONS—houses the settings for METARs, PIREPs, Satellite, and RADAR which are accessed by clicking their respective tabs. Note: Users can reorder the tabs by simply clicking and dragging them.

GFA Observation Menu - METAR Tab
Figure 8.1: Observations Menu - METAR Tab


METARs are depicted using the standard station model. A priority scheme is used for progressive display of station plots, therefore, the higher the zoom level, the more stations will be shown. The density for a particular zoom level can be changed with the "Show" dropdown. Selecting "More" will roughly double the number of stations in the plot. Conversely, changing the "Show" value to "Less" will cut the number in half.

When larger or smaller METAR station icons are desired, use the "Scale" dropdown to alter their size. Additional options include displaying TAF data in conjunction with METAR observations, and changing data to metric units. Clicking on a station plot displays a pop-up box containing the latest METAR information. By default, the text data is displayed in a decoded format; however, the user has the option to view raw text by unchecking the "Decode" box.

GFA Observation Menu - PIREP Tab
Figure 8.2: Observations Menu - PIREP Tab


Like the METAR/TAF plots, the size of the PIREP icons can be changed by adjusting the "Scale" setting. Note: PIREPs may not be turned off however a time window may be specified by selecting the criteria in the "Age" drop-down menu. The default age of PIREPs is 90 min. Options are available to view PIREPs submitted within 30, 60, 90 minutes and 2, 3, 4, 6, or 12 hours of the current time.

The "Min. Intensity" dropdown allows the user to view all PIREPs or only those that equal or exceed light, moderate, or severe intensity. Text information is obtained by hovering over a PIREP or clicking on the symbol. A two or three digit number under the PIREP symbol indicates the flight level of the report.

GFA Observation Menu - SAT Tab
Figure 8.3: Observations Menu - SAT Tab


Note: Satellite imagery is ONLY available for OBS/WARN products.

The layer visibility can be toggled on or off via the checkbox preceding "Satellite." Layer transparency can be adjusted using the "Opacity" selector. Satellite imagery is available in either 10km infrared, water vapor, or 5km visible. The default imagery is "Infrared," however, visible and water vapor imagery may be displayed via the "Type" dropdown. The latest image available for the selected time is used.

GFA Observation Menu - RADAR Tab
Figure 8.4: Observations Menu - RADAR Tab


Note: RADAR imagery is ONLY available for OBS/WARN products.

Radar imagery is displayed as a loop of five images ending in the latest available time. The loop represents a 40 minutes timeframe, and can be toggled off by unchecking the "Loop" box. The default "Type" is the "Lowest Angle" image, but the user can change it to composite images via the drop-down.

Map Base, Domain & Format

These settings allow users to change the way the underlying map looks, show/hide domain boundary lines, display local time, and manipulate a multitude of other presentation options.

GFA Map Base, Domain and Format Options
Figure 9: Map Base, Domain & Format Options

Use local time - By default the times are depicted in UTC (GMT). Users may elect to use local time by checking this box.

Click on hover - By default, features on the display have to be clicked to display the pop-up text information boxes. This is done for mobile devices that do not support a hover feature. By toggling hover on, the features will automatically show the popup when the pointer is moved over them.

G-AIRMET domain - Toggles the visibility of the G-AIRMET domain which is depicted with a purple boundary line.

GFA domain - Toggles the visibility of the GFA domain which is depicted with a blue boundary line.

Basemap - The GFA display has a selection of six base maps. The default is the light map, which uses the NASA blue marble background. Users can also select a dark NASA blue marble background, a terrain, road, satellite, or simple map.

  • Light - This is a simple light background based on the NASA blue marble image. This shows no detail, which might be desirable for some more complicated displays. This will not show roads so using the highway and road overlay is useful with this basemap.
  • Dark - This is the NASA blue marble image. This shows no detail which might be desirable for some more complicated displays. This will not show roads so using the highway and road overlay would be useful with this basemap.
  • Simple - This is a blank white background which again might be desirable for some complicated displays and output to a printer.
  • Terrain - Boundary lines, water features and roads are overlaid on a hillshade map.
  • Road - Displays street-level data, including highways, major and minor roads, railways, and water features overlaid on a shaded relief map.
  • Satellite - Displays satellite imagery and high-resolution aerial imagery.

Domain - Clicking CONUS will re-center the display, and zoom to show the entire continental US and coastal waters. When moving the mouse over the image, the cursor location will be displayed in the lower right corner.

Coordinates - The user may select to have the location displayed in decimal degrees or degrees:minutes:seconds.

Map Features

In addition to weather overlays, many non-weather overlays are also available. These have been grouped into three tabs "Airport," "Nav," and "Roads/Rivers."

GFA Map Features - Airport Tab
Figure 10.1: Map Features - Airport Tab

Airport Tab

These checkboxes allow users to display and filter icons of airports and heliports across the United States. Due to progressive display, this information is only visible at a sufficient zoom level. The Airports overlay displays all airports and heliports contained in the NASR 28-day update. Airports have small airplanes inside the circle and heliports have an "H." Each icon can be clicked to show a popup with site-specific information. The size of the icons can be changed with the "Scale" dropdown. Airport IDs, runways and taxiways can also be toggled on and off by using the appropriate checkboxes.

Airport Symbols

Airport, multiple runways, hard surface ≥ 8100 ft, with beacon, with services
Airport, single runway, hard surface ≥8100 ft, with beacon, with services
Airport, multiple runways, hard surface ≥ 1500 ft < 8100 ft, with beacon, with services
Airport, multiple runways, hard surface ≥ 1500 ft < 8100 ft, with beacon
Airport, multiple runways, hard surface ≥ 1500 ft < 8100 ft, with services
Airport, multiple runways, hard surface ≥ 1500 ft < 8100 ft
Airport, single runway, hard surface ≥ 1500 ft < 8100 ft, with beacon, with services
Airport, single runway, hard surface ≥ 1500 ft < 8100 ft, with beacon
Airport, single runway, hard surface ≥ 1500 ft < 8100 ft, with services
Airport, single runway, hard surface ≥ 1500 ft < 8100 ft
Airport, short or unpaved runway, with beacon, with services
Airport, short or unpaved runway, with beacon
Airport, short or unpaved runway

Private Airport
Generic Airport
Seaplane Base

Note: Runway configurations not represented in airport icons.

Nav Tab

The Nav tab provides the ability to view and hide major navigational aids. As the map zoom level increases, more icons will be displayed.

GFA Map Features - Nav Tab
Figure 10.2a: Map Features - Nav Tab

Fixes-Hi - Displays High level route fixes.

Fixes-Lo - Displays Low level route fixes.

NAVAIDs - This displays basic navigation aids such as VORs, and DMEs. These will only display at a sufficient zoom level. When this layer is turned on, a display of direction and distance to the nearest navaid will display in the lower right corner. In figure 10.2b (below) note that the crosshair cursor is located 47 statute miles ENE of the Maples VORTAC.

Navaid SymbolType
GFA Map Features - Nav Tab - Nearest Navaid
Figure 10.2b: Nav Tab - Nearest Navaid

Show IDs - Displays navaid text identifier.

Jetroutes - Displays major upper level jet airways.

Airways - Displays the Victor Airways.

Airspace - Displays Class B, C, D, and E airspace.

ARTCC/FIR Boundaries - Displays air traffic control regions.

Roads/Rivers Tab

Allows user to toggle the display of highways, county lines, etc. The visibility of these features is dependent on the zoom level of the map.

GFA Map Features - Roads/Rivers Tab
Figure 10.3: Map Features - Roads/Rivers Tab

Highways - Displays interstates in the US and major highways in other countries. Even though the ESRI basemap has highways terrain and road views, it can be difficult to see them with data overlaid. This adds an additional overlay.

Roads - Displays US, state highways and major city roads depending on the zoom level.

Counties - Displays US county outlines.

Rivers - Displays major rivers. Smaller rivers appear as the zoom level increases.

Flight Path Tool

Selecting the "Show Flight Path" button near the upper right hand side of the map (fig. 11) opens the flight path dialog box (fig. 12) which allows users to enter a period-separated list of airports and/or way points.

Note: Currently, only periods work as delimiters.

GFA Flight Path Tool
Figure 11: GFA Flight Path Tool - Button
GFA Flight Path Tool
Figure 12: GFA Flight Path Tool - Dialog

When the form is submitted with the "Enter" key (fig. 13), a bold pink line will be drawn on the display between the points. Clicking on the Hide Flight Path button (fig. 14) will hide the input form, but leaves the flight path line visible. To remove the flight path, clear the form and resubmit (or simply refresh the page).

GFA Flight Path Tool - Show
Figure 13: GFA Flight Path Tool - Enter
GFA Flight Path Tool - Hide
Figure 14: GFA Flight Path Tool - Hide