What do the various storm symbols represent?

Green Circles:

The solid dark green circle means that there is 50% chance or greater of hail that is smaller than 19 mm (3/4 of an inch).

The hollow dark green circle means that there is between 30 - 50% chance of hail that is smaller than 19 mm.

The solid light green circle means that there is 50% chance or greater of severe hail (hail that is 19 mm or larger).

The hollow light green circle means that there is between 30 - 50% chance of severe hail (hail that is 19 mm or larger).

Coloured Rings:

The broken rings are shown when the base of a mesocyclone (a rotating thunderstorm) is aloft (ie. not on the lowest tilt).

The solid rings are shown when the mesocyclone base is on the lowest tilt.

The color "heat" of the icon represents the strength (very weak is light green, weak is green, moderate is yellow, strong is red, extreme is purple). GRLevel3 uses the "strength rank", SR, to choose an icon. The first icon is shown for SR values of 1-2, second for SR values 3-4, third for 5-6, fourth for 7-8, and fifth icon for 9 and above.

Tornado Vortex Signature (TVS)- Area defined on radar to have strong low level rotation and may have the potential to produce a tornado. Also known as a "Doppler-indicated tornado." These should be monitored very closely. Keep in mind that these sometimes show up and then quickly disappear; it does not mean that the storm is indeed producing a tornado.