The timeline at the bottom of the screen lets you move through time. It only appears when there is time-stamped data to browse:
- a displayed GRIB file;
- a visible routing;
- the current atlas (Current atlases box in the layers menu);
- the rain radar.
If it has disappeared, there are two possible causes.
1. You collapsed it
A small chevron handle, on the top edge of the timeline to the right of the time bubble, collapses the timeline and opens it again. Once the timeline is collapsed, the handle stays visible at the bottom of the screen: tap it to bring the timeline back. This choice is remembered on the device, even after restarting the app.
On a phone held in landscape, the timeline becomes a column on the side of the screen; its handle then sits against that column.
2. No GRIB is displayed
Without a visible routing, the current atlas or the rain radar, the timeline only appears when a GRIB is displayed. Tapping the GRIB that is already displayed in the list deselects it: the chart no longer shows a forecast and the timeline disappears.
To fix this, open the left panel with the chevron handle (›) on the left edge of the screen, choose the GRIBs tab and tap a file to display it, or download one.
See also: How do I download a GRIB file?