Rain and snow mixed and snow. Though no "official" criteria exist for the term, in the United Kingdom the term is not used when any significant accumulation of snow on the ground takes place. It is often used when the temperature of the ground surface is above , preventing accumulation from occurring even if the air temperature is marginally below ; but even then, the falling precipitation must generally be something other than exclusively snow. In the United States, wintry mix generally refers to a mixture of freezing rain, ice pellets, and snow. In contrast to the usage in the United Kingdom, in the
Hail spike Hail spike A hail spike or three body scatter spike (TBSS) is an artifact on a weather radar display indicative of large hail. They are identified by a spike of weak reflectivity echoes that extend out from a thunderstorm, and away from the radar site. Generally known as hail spikes, these are the result of energy from the radar hitting hail, or very heavy rain, and being reflected to the ground, where they reflect back to the hail and then to the radar as in the image on the left. This results in the radar picking up the energy from