RadarNow! uses two sources for radar imagery. The composite view, or the overall view that can be zoomed out to show the entire country, is constructed by stitching together the imagery from each individual radar station.

These individual stations operate independently and take their radar snapshots depending on local conditions. The rate at which the station takes snapshots can vary from one every thirty minutes or even more to the more average once every six minutes or in the case of extreme weather coming from one direction, three minutes.

The composite is built on a schedule that’s typically once every ten minutes. By the time the composite is built, some of the imagery could be more than ten minutes old, depending on when the last image was collected. The time that scrolls across the top of the screen is the time that the composite was built, not the time the radar image was taken.

RadarNow! uses both the composite view, which is better for viewing the overall and wider picture, and the local radar station’s direct feed, which will show the latest image produced.

In normal operation, RadarNow! automatically switches between the composite view and the local view as the screen is zoomed. When viewing a local radar station, the image is zoomed out, the view mode will switch to the composite at an appropriate level. Same with zooming in. If the view is composite and the screen is zoomed in close enough, the local station’s radar imagery will be displayed.

To manually switch between the two modes, we offer two methods. The first is to use the left navigation menu (three horizontal bars, top-left) to select the composite or local mode. The second method is to do a long press on the zoom buttons. To switch from composite to local, long press the zoom in (+) button. Switch from local to composite by long pressing the zoom out (-) button.

Using the long press method allows comparing the two radar sources rapidly.

Here’s a video showing the long press in action. Note the button presses are not visible.