Radar Symbols

What do the various lightning symbols represent?

The above are lightning data symbols where (from top to bottom):

First Row Means 16-30 minutes old
Large Icons Mean 16+ strokes 
Second Row Means 11-15 minutes old
Medium Icons Mean 11-15 strokes
Third Row Means 6-10 minutes old
Small Icons Mean 6-10 strokes
Fourth Row Means 5 minutes or less
Tiny Icons Mean 5 strokes or less

 

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.

What is "Tilt":

This is a display of echo intensity (reflectivity) measured in dBZ (decibel scale). The base reflectivity images in GRLevel3 are available at four radar "tilt" angles, 0.50, 1.50, 2.40, and 3.40. A tilt angle of 0.5 means that the radar's antenna is tilted 0.5 above the horizon. Viewing multiple tilt angles can help one detect precipitation, evaluate storm structure, locate atmospheric boundaries, and determine hail potential.

Radar symbol explanations courtesy of Patrick Marsh of Forwarn.org