Table of Contents

1. About and contact information

AWeather was created in the summer of 2008 and functions as a NEXRAD Level II radar display program. The goal of this application is to fulfill a need through providing ample weather information without excessive cost and size that is not limited to the Linux operating system.

It is written in a standard GTK+/GObject architecture and features an interactive display utilizing Grits and OpenGL technologies.

The software source code is available for download at git://

AWeather relies upon the following dependencies: gtk+ 2.18 or later, libsoup 2.26 or later, bzip, rsl 1.42 or later, and others.

Packaged versions of the software are currently available for Gentoo, Debian, Ubuntu, Microsoft Windows, and Mac OSX operating systems.

The program currently provides data viewing from the standard two dimensional plan view to user-defined three-dimensional dynamic views of current and recent radar data.

The software was developed and is maintained by Andy Spencer. He may be contacted through e-mail at and chat through IRC at #pileus on

2. Licensing information

AWeather is provided as free software according to the terms of the GNU General Public License (version 3 or later) as published by the Free Software Foundation (

3. Data types and sources

AWeather displays U.S. National Weather Service NEXt generation RADar (NEXRAD) Level II data. This is the highest resolution form of radar data available in the public domain and consists of multiple tilts of data updated every 5 to 10 minutes depending on the current scan mode of each radar.

The following Level II data types are supported by this program:

  • Base reflectivity (power return of current precipitation intensity)

  • Base velocity (Doppler-derived speed and direction of radar returns)

  • Spectrum width (The variation of velocity detected within each radar pixel or bin)

  • Differential Reflectivity (The ratio of the reflected horizontal and vertical power returns)

  • Differential Phase (A comparison of the phase difference between the horizontal and vertical returns)

  • Correlation Coefficient (A statistical correlation between the reflected horizontal and vertical power returns)
    [Only available at WSR-88D sites that have been upgraded to support dual-polarization]

Level II data has been available through private weather data vendors for some time but recently has been generously provided by some universities.

AWeather requires an active internet connection along with a data source in order to retrieve, decode and display current or recent radar data.

The default radar feed is publically accessible thanks to Iowa State University and is located at:

AWeather also displays some severe weather alerts provided by the NOAA weather alerts feed.

When run under Linux, AWeather can interface with the GPSd location services to track and display the user’s current location.

4. Program layout

AWeather consists of a graphical user interface window that contains a file menu bar, a button bar, a date and time side bar, a large map and data viewing pane and a bottom data status bar.

5. The file menu commands

The program file menu consists of 5 entries:

5.1. File


stops the program from downloading data through the internet


reloads the current display


automatically refresh the the radar after a certain delay

Clean cache

removes data files from the program’s internal cache


closes the program window and exits from memory

5.2. Edit


opens the preferences window, which contains the following commands

General tab
Offline checkbox

if selected keeps the program from connecting to the internet

Update Freq

sets the timeout value for automatic updating

Initial site listbox

allows the user to select a default radar site to jump to when the program loads

NEXRAD URL text box

allows the user to select a different server to download Level-II NEXRAD data from

Debug level text box

allows the user to select what level of debugging the program should conduct while running (7 is recommended only for debugging)

Plugins tab
alert checkbox

allows the user to toggle the weather alerts

elev checkbox

allows the user to toggle terrain rendering

env checkbox

allows the user to toggle a blue atmosphere and compass rose

gps checkbox

allows the user to toggle gps tracking [Linux only]

map checkbox

allows the user to toggle the map overlays

radar checkbox

allows the user to toggle the radar data

sat checkbox

allows the user to toggle satellite ground images

test checkbox

used by the developers for debugging

5.3. View

Zoom in

decreases the viewing area

Zoom out

increases the viewing area


maximizes the window and only displays the button menu bar along with the map and data viewing pane when the mouse is moved to the edge of the screen

5.4. Radar

The radar menu contains list of all the support NEXRAD radar sites sorted by state. Selecting a site will zoom AWeather to that location.

5.5. Help

User Guide

displays this documentation of program operation and features

Man Page

displays a HTML version of the UNIX man page


contains current program version, copyright, development site, credits and licensing information

6. The button bar

The program button bar contains 6 options:

Magnifying glass with plus sign

decreases the viewing area

Magnifying glass with minus sign

increases the viewing area

Window icon with expanding arrows

Toggles between fullscreen and normal viewing modes

Plug button

toggles between offline and online program mode

Circular arrow button

reloads the current display

Wrench and screwdriver button

Opens the preferences window

7. The date and time side bar

The date and time side bar resides on the right side of the program window, it contains:

  • The date button, which reveals a calendar of the current month when clicked

  • The time button, which reveals a list of each hour when clicked

    • Clicking on an hour will reveal a list of times in 5 minute intervals that the user can select to load radar data from
      [Radar data can only be loaded if it has been previously cached or is from a recent enough date and can still be obtained from the NEXRAD server]

8. The map and data viewing pane

On program startup and when zoomed far from the earth’s surface AWeather displays a national radar composite image.

Each available radar site is displayed on the map using the name of a nearby major city. Clicking on the city label will activate the radar site and center it in the viewer.

As the user zooms closer to the earth AWeather will automatically activate nearby radar sites.

The radar data will be plotted on the map while the scan and product information will be displayed at the bottom of the program.

All active radar sites will show as tabs while site’s available tilt and product data will display to the right of the tab.

Simply click on a button to display that product/tilt in the map window.

An isosurface slider is shown below the product/tilt buttons. Slide the selector to reveal the rendered isosurface structure of reflectivity data.

A color scale will automatically appear at the top left corner of the map window corresponding to each available product.

9. Viewing severe weather alerts

When the alert plugin is enabled, AWeather will automatically shade each county that is under a weather alert in a color corresponding to the type of alert.

For storm based warnings, AWeather will also draw a polygon representing the warning area.

Individual alert types can be enabled and disabled by clicking on the toggle button in the alert tab at the bottom of the screen.

To view more information about a particular alert, click on one the shaded county or inside the polygon warning area in the viewing pane. This will bring up the alert details dialog with a tab for each alert that is active for the location that was clicked.

The alert dialog displays the alert title and valid time along with the text descriptions provided by the weather service. Clicking the "Full Text" button will open the full text of the alert in a web browser.

10. Panning, zooming and tilt functions

AWeather supports the use of the mouse and keyboard commands to change the map window settings.

When the map is rotated, a red and white compass in the top right corner shows the current direction of North. Clicking on the compass will reset the rotation so that north points toward the top of the screen and the viewer is pointed towards the ground.

Mouse usage
Left click and drag

Pan the surface of the earth

Middle click and drag

Zoom toward or away from the earth

Right click and drag

Rotate the camera left or right

Keyboard shortcuts

Pan left


Pan down


Pan up


Pan right

i, +, Scroll Up

Zoom in

o, -, Scroll Down

Zoom out


Rotate camera toward earth


Rotate camera toward sky


Rotate camera left


Rotate camera right


Draw wire frame of the earth (for debugging)


Exit the program


Cycle through available plugins


Close the currently active dialog box


Refresh the display

11. Command Line Options

The following command line options can help advanced users take full advantage of the AWeather program:

aweather [-hoaf] [-d level] [-s site] [-t time]

-h, --help

Show usage.

-d, --debug=level

Change default log level*, a debug level ranges from 0 to 5. A debug level of 5 is recommended only for debugging purposes.

-s, --site=site

Set initial site. The site should be given as a WSR88D site code such as KLSX.

-t, --time=time

Set initial time. The time format should be provided in the YYYY-MM-DD HH:MM format.

-o, --offline

Run in offline mode, AWeather will not attempt to connect to the internet to download radar files but will show the closest matching cached file.

-a, --autoupdate

Run in autoupdate mode, AWeather will periodically poll data servers for updated information.

-f, --fullscreen

Run in fullscreen mode, AWeather start up using the entire screen as he main display area. Toolbars and side panels are hidden by default.

12. Future Features

The author intends to develop additional features in the future as time and conditions allow.

Some of these enhancements include:

  • Vertical cross sections

  • Support for derived L3 data (storm relative motion, echo tops, composite reflectivity, etc)

  • Additional data sources for surface data, etc

  • Animation support

  • API for radar algorithms

  • Additional features