25 May 2019

Weather Radar Mistakes Can Often Give Valuable Information

Posted by Dan Satterfield

Look at this image below from the NOAA Doppler Radar near Midland TX.

What is that strange spike coming out of the storm? We actually have a name for it and you do not see one like that very often. It’s called a 3 body scatter spike. There is no long line of rain falling from this severe storm, and believe me it’s without a doubt very severe.

Instead, the radar beam is bouncing off very large hail in the middle regions of the storm. The hail is slowly melting and has a coating of water around it, and water coated ice turns out to be a very strong reflector of electromagnetic waves at the frequency used by Doppler weather radars (wavelength of around 10 centimeters). The beam hits the hail and gets bounced forward and down to the ground, then bounces back to the ice and back to the radar. This causes the signature you see here. It’s a classic signature of hail the size of grapefruit!

Yes, indeed the NWS warned residents of large hail with this storm.