Why do areas of widespread rain sometimes appear and disappear on the 512km composite image?
The 512km composite images are unique as they are a composite of all available radar images and sometimes several radars may contribute to the overall view. Some radars in the Bureau network are windfinding radars, which means that there are certain times of the day in which they do not provide input to the 512km composite radar views (click here for more information about the routine windfind time periods). As a result, when widespread rain is evident in the region it can sometimes disappear from the radar image between one frame and the next. This happens because the nearby radar has switched to windfinding mode. Similarly rain can sometimes appear after the windfinding radar switches back to its normal mode. The Bureau’s windfinding radar sites are shown on the radar home page map as blue squares.
