Max Size

Radar also tries to determine the maximum diameter of hail falling within a storm cell. The output from this is formatted into inches and placed in the "Max Size" column of the storm attribute table.

The size that is estimated by radar is usually overstated and the majority of hail that falls is generally smaller. This is especially true during the summer months. The National Weather Service radar operators tend to only use the maximum hail size to issue warnings when the probability of severe hail (POSH) is over 50%.

Radar hailstone estimates range from <.50 inch to >4.00 inches in diameter by quarter (.25) increments.

Cells that are a great distance from the radar site, as well as those which have just developed, may have an unknown, or undetectable, probability. Check the next scan to determine if the unknown probability has been resolved. If not, try using a different radar site that the storm cell may be closer to. Thunderstorm cells that have an unknown probability also have an unknown maximum hail size. Either all hailstone-related information is present, or none of it is.

Radar may not detect the probability of general hail and severe hail with great accuracy, or possibly at all, if a thunderstorm is too close to the radar site. Beams from the radar's transmitter may not enter into the updraft at or near the proper angle to make accuracy possible.

With that said, it is also possible for storms to weaken. Therefore, it is good practice to check the atmospheric conditions before judging that the "cone of silence" is responsible for the weakening maximum hailstone sizes.

Never question the decision of an expert meteorologist to issue or withhold a warning.