Insider Blog: Recent storms drop piles of hail that look like snow

A cold front tracked through Mid-Missouri on Sunday, bringing elevated thunderstorms that produced heavy rain and hail through the southern half of the area into the evening.

Most of the storms stayed below severe limits, but a few were able to produce large volumes of hail that piled up across Morgan and Miller counties, and even had some egg size stones mixed in.

The large amounts of hail covered the ground like snow across north central Miller County, particularly near Eldon and Tuscumbia. Miller County 911 Dispatch reported multiple accidents after 8:00 p.m. on Sunday night due to slick, icy conditions on Highway 54.

Hail forms as water droplets in the lower part of the storm are forced up past the freezing level at the top of the storm by the storm's updraft, the winds allowing the storm to grow and sustain itself. Stronger updrafts allow supercooled water droplets to continue riming onto the existing stones as they remain suspended in the frozen layer by the updraft. Once the hail gets too heavy for the updraft to hold it up, the hail falls through the downdraft to the ground. The stronger the updraft winds, the more cycles hail can take through the storm to grow.

In the case of the Miller County hail, that storm took on more "mini-supercell" characteristics as it reached about 30,000 ft at its tallest. Most supercells average between 45,000-50,000 feet.

The storm had a low freezing level at about 12,000 feet, and a deeper warm layer below as temperatures at about 1 mile up into the storm were in the upper 50s to about 60 degrees. Hail stones were able to form in the freezing layer, but had more time to melt and fall down easily as wind speeds through the middle and upper part of the storm only reached about 35 mph.

Storms with updrafts past 80 mph can produce very large hail, greater than the size of grapefruits, but are much more rare.