Hail is a form of precipitation consisting of solid ice that forms inside thunderstorm updrafts. Hail can damage aircraft, homes and cars, and can be deadly to livestock and people. What we do: Read more about NSSL's hail research here. How does hail form?

What we do: NSSL is developing techniques to use dual-polarized radar data in short-term computer forecast models to improve forecasts of hail and large hail. Dual polarized radar data gives meteorologists information on the size of hail particles within a storm, as well as the distribution of hail sizes.

Severe Weather 101 Frequently Asked Questions About Hail Why does the sky look green during some hail storms? Scientists don't agree on why the sky may appear green during severe weather, although there is plenty of anecdotal evidence that it can mean hail may be nearby.

Dual-polarization radar can distinguish between rain, hail, snow, or ice pellets inside the clouds. NSSL scientists are developing algorithms that will produce estimates of whether the precipitation is reaching the ground or whether it is falling in liquid or frozen form.

Severe Weather 101 Hail Detection. Hail can be detected using radar. On Doppler radar, hail generally sends a return signal that looks like extremely heavy rainfall. Dual-polarization radar technology, used by the NWS, can help tell the difference between hail, ice pellets and rain, and even determine hail size.

NSSL's On-Demand web-based tool helps confirm when and where severe weather occurred by mapping circulations or hail detected by radar on Google Earth satellite images. NWS forecasters can quickly review warnings and check their accuracy with this system.

Sometimes a flash flood threat is overshadowed by other severe weather events happening at the same time. The main tools used to detect heavy rainfall associated with flash floods are satellite, lightning observing systems, radar, and rain gauges.

Severe Weather 101. Step into the wild world of weather! What is a wall cloud? What's the difference between a watch and a warning? Is it ever “too cold to snow”? Learn all about thunderstorms, tornadoes, hail, lightning, floods, damaging winds and severe winter weather.

Severe Weather 101 Thunderstorm Types. Often called “popcorn” convection, single-cell thunderstorms are small, brief, weak storms that grow and die within an hour or so. They are typically driven by heating on a summer afternoon. Single-cell storms may produce brief heavy rain and lightning.

A thunderstorm is classified as “severe” when it contains one or more of the following: hail one inch or greater, winds gusting in excess of 50 knots (57.5 mph), or a tornado. How many thunderstorms are there?