Radar imagery: weather office tour
Our forecasters can look at pictures from any of Environment Canada's radar systems. They have lots of options on how to display the images. They can look at radar pictures from a single location or from several radar sites combined. They can look at a still picture or a series of them in an animated loop like a movie. They can look at a picture of the precipitation close to the ground or in the very tops of thunderstorm clouds.
The larger and more plentiful the precipitation droplets are within a cloud, the stronger the radar signal will be. By looping together several radar pictures, forecasters can monitor how storms are developing and where they are moving. Once a potentially damaging storm has been identified, forecasters can issue severe weather warnings for communities in its path.
The picture on the left has a coloured legend on the side, with each colour representing a different signal strength. Stronger signals mean potentially heavier precipitation. This picture is from the King City radar near Toronto, and the enlargement to the right shows the strong thunderstorm cells that prompted Environment Canada to issue a severe thunderstorm warning for parts of southern Ontario that day.
Some weather systems are so large that they cover more than one part of a province, and forecasters will use the combined radar pictures from several locations so that they can see the whole precipitation pattern as you see on the left. You can see today's radar pictures on our main weather Web site.
Doppler radar shows all of the things a regular weather radar detects. It also determines how the precipitation is moving within the cloud, whether the droplets are moving toward the radar antenna or away from it. In this example, the radar antenna is in the middle of the picture, and precipitation is moving up from the southwest. The blue area shows precipitation moving toward the radar and the pink area shows droplets that are moving away from it. Variations in this pattern will show forecasters the wind patterns within storms. This helps them to identify tornadoes as they are forming so that earlier warnings can be issued.
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