This section provides information on effectively using the Graphical Forecasts for Aviation displays. The following topics are covered:
The Forecast and Obs/Warn tabs determine the options of preset graphics available to view, shown by the tabs located above the main menu abr. 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.
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.
Details of the data in each tab option can be found under the Products info page.
The Settings tab enables the user to adjust the view from the default which is automatically selected with each weather tab.
By default, features on the display have to be clicked on to show the popup 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 mouse is moved over them.
SIGMETS, G-AIRMETS, NWS warnings, and model gridded data can all be toggled on or off. The opacity may also be changed in the drop-down menu.
METARs and TAFs are displayed using the standard station model. Weather overlay displays only the pertinent weather symbol for the selected tab, and may be selected off. Clicking on the station plot will bring up a text box with the latest METAR or TAF information. The text data is displayed in a decoded format; however, the user has the option to view raw text by unclicking the "decode" box. Additional options include displaying the TAF data in conjunction with the METAR observation, and changing all the data to metric units.
The user also has the option to increase the number of weather overlays, METARs, and TAFs displayed by changing the density. A priority scheme is used for progressive display of station plots. The higher the zoom level, the more stations will plot; however, the density for a particular zoom level can be changed through the density pull-down menu. Going to "more" will roughly double the number of stations in the plot. Going to "less" will cut the number in half. The Scale setting will alter the size of the data icon on the screen. In some cases, a larger icon is desired.
PIREPs may not be turned off; however, the user may choose to display PIREPs issued within a specified amount of time by selecting the criteria in the "Age" drop-down menu. The default age of the PIREP is 90 min. Options are available to view PIREPs submitted with 30 min, 1-4 hr., 90 min, 6 hr., or 12 hours of the current time. Like the METAR/TAF plots, the size of the PIREP can be changed by changing the scale. The "Min. Intensity" pull-down allows the user to select 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.
Satellite imagery is available in either 10km infrared, water vapor, or 5km visible. The default imagery is Infrared, but the user can select another option in the Settings menu. The latest image available for the selected time is used.
Radar imagery from the MRMS data is displayed as a loop of 5 images ending in the latest available time. The loop is over 40 minutes, and can be toggled off by unchecking the box. The default is the base or lowest angles image, but the user can change it to a composite image.
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.
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. The user may select to have the location displayed in decimal degrees or degrees:minutes:seconds.
In addition to weather overlays, many non-weather overlays are available. These can be enabled by clicking the box next to the title.
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 FL 480, 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 in the Products info page.
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 including satellite imagery, Current/Forecast Icing Products (CIP/FIP), National Digital Forecast Database (NDFD) and NOAA Rapid Refresh (RAP) model data. 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.
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.
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.
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.