by: John Fuller - Meteorologist
(KSDK) -- Thunder sleet is similar to thunder snow and thunder showers in the sense that convection is taking place within the cloud. That is, rapid updrafts and downdrafts are causing friction within the cloud producing strong positive and negative parcels within the cloud. When these oppositely charged parcels collide, you get lightning and hear thunder.
When the rain falls from the cloud, through a layer just above the ground that is below 32 degrees (today it's is 25-29 degrees), the droplets freeze into granules that look like diamonds. If the rain aloft that falls is warm enough, it may not freeze until it hits the sub-freezing surface resulting in thunder freezing rain and a glaze at the surface.. The key in having any 'thunder' precipitation is convection or strong updrafts and downdrafts causing enough friction and charged particles to produce lightning. Thunder is the sound resulting from the lightning that super heats the air around the bolt.