The NEXRAD radar network was developed by the National Weather Services in the 1980s and first deployed in the early 1990s. In the years since advances in technology and communications have allowed them to improve the quality of radar products. The "Classic Products" in RadarScope date back to the original NEXRAD Level III product suite. Most of them of been superseded over the years by better alternatives, but they can still be used for reference purposes or when using RadarScope on a low-bandwidth connection.
Digital Vertically Integrated Liquid
Vertically integrated liquid (VIL) estimates the amount of water in a column of air. High values for VIL can indicate heavy rainfall or the presence of hail. When VIL values fall rapidly, it may suggest a downburst. VIL is subject to radar limitations and seasonal dependencies, so it's a tricky product to interpret. Learn more about VIL on our blog or on Wikipedia.
Enhanced Echo Tops
The echo tops product shows the maximum height of precipitation echoes detected by the radar between 5,000 and 70,000 feet that exceed 18 dBZ. Higher echoes are often associated with stronger areas of a storm. This product is useful for identifying strong updrafts, and a sudden drop can indicate the onset of a downdraft. Some storms are too close to the radar for the beam to see the top, so echo tops are often underestimated for strong storms near the radar. The enhanced echo tops product incorporates two elevation ranges. The first applies a multi-color scale to values that could be determined within highest beam angle. The second, grayscale color range indicates that values that may have exceeded the height of the radar beam.