Types of storms in Mid-Missouri

Thunderstorms are common in the spring and summer months, and sometimes can turn severe.

A storm is considered severe if it is producing winds of 58 mph or greater, 1″ hail or larger, or a tornado.

The structure and formation of a storm can give meteorologists insight on what type of severe weather threat will come from certain storms.

There are three typical formations: isolated cells, supercells, and linear cells.

In Mid-Missouri, we get all structures and all forms of severe weather, but some types are more common during certain months.

In March and April, it’s more common for a severe threat to be large hail, as opposed to straight line winds. These thunderstorms are isolated cells or multi-cells. The main ingredient for hail formation is where the freezing line is located. Freezing temperatures are needed in order for ice to form and supercooled water droplets to aggregate to.

As a rule of thumb, if the freezing line is below 12,000 feet, this is cold enough aloft for hail to reach the surface, as opposed to June and July the freezing line is further aloft, the hail has enough time to melt and fall as liquid.

In June and July, the surface is heating up. The main ingredient here is the temperature. The warmth creates instability or lift in the atmosphere. The warmer the temperature, the more instability is provided.

Another severe threat is damaging winds. Storms need updrafts and downdrafts in order to be sustained. Instability causes a greater updraft, which results in a greater downdraft. We see this greater instability in late spring and early summer.

Finally, tornadoes are another severe weather threat. Most tornadoes are spawned from supercell thunderstorms. While tornadoes can occur at any time of the year, they are more likely to form in mid-May to early June. The classic structure of a supercell storm may have a flat updraft base and wall cloud underneath its updraft. When conditions are right, a tornado will form underneath the wall cloud. A classic supercell will also have rotation, creating a hook when it’s displayed on radar reflectivity. This classic hook indicates possible rotation.