How NOAA Doppler Radars Work

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There seems to be some confusion about whether or not the radar image you see on WBOC is live. The answer is that it is live, but the radars take a look at the entire atmosphere in what is called a volume scan. This gives we meteorologists very valuable information on how strong a storm is and also what the winds aloft are doing. To do this, the radar sends out a narrow pencil like beam at an elevation of about 0.5 degrees to start, then after one revolution it tilts up to 1.5 degrees and does the same. This continues until a sample of the entire atmosphere up to at least 70,000 feet is completed. This takes the radar from 3 to 5 minutes depending on the scanning mode that is being used. Different weather conditions can require shorter or longer scan times.

This is a NEXRAD Doppler product called Hydrometeor classificaton. It is showing what the radar is seeing. Green is rain but it can detect bugs, ice, snow, or hail.

This is a NEXRAD Doppler product called Hydrometeor classificaton. It is showing what the radar is seeing. Green is rain but it can detect bugs, ice, snow, or hail.

We usually show the lowest tilt when airing the radar image (although not always) and it may take 3-5 minutes for each individual radar to update. Since we show at least three radars on the map, one of them is usually updating every minute or so. So, this is a case where it is better to wait a minute to get the entire picture! These Doppler radars are called NEXRAD 88D and they have improved severe weather warnings immeasurable over the last 20 years! You actually see only a few of the many products that come out of these radars, since some of the data is rather complicated, and takes training to understand and interpret correctly.

Hopefully, you now have a better idea of how this works and now that the new GOES-16 Weather satellite is in orbit, we get satellite images about every 5 minutes to go with the radar. This gives us even more important information about the structure of the storm and whether the top of the cell is still climbing higher or is beginning to fall down somewhat. A strong updraft will cause the cell to keep climbing and could indicate the storm is still strong or getting even stronger.