DAX Radar
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Vertically Integrated Liquid Water (VIL)

VIL is the amount of liquid water that the radar detects in a vertical column of the atmosphere for an area of precipitation. High values are associated with heavy rain or hail. VIL values are computed for each 2.2×2.2 nm grid box for each elevation angle within 124 nm radius of the radar, then vertically integrated. VIL units are in kilograms per square meter–the total mass of water above a given area of the surface. VIL is useful for:

  1. Finding the presence and approximate size of hail (used in conjunction with spotter reports). VIL is computed assuming that all the echoes are due to liquid water. Since hail has a much higher reflectivity than a rain drop, abnormally high VIL levels are typically indicative of hail.
  2. Locating the most significant thunderstorms or areas of possible heavy rainfall.
  3. Predicting the onset of wind damage. Rapid decreases in VIL values frequently indicate wind damage may be occurring.