What Is a Dryline? The Key to Predicting Severe Storms

Severe weather season is here, spurring talk of cold fronts, squall lines, supercells, and more. While the term "dryline" might not be as well-known as some of the most commonly used weather terms that relate to severe weather, there is no mistaking the importance of this atmospheric feature when it comes to forecasting. Here is a closer look at drylines and how meteorologists use their presence and location to make forecasts.

What is a Dryline?

Drylines are boundaries that are associated with large areas of low pressure. These boundaries often serve as the building blocks of severe weather events, particularly in the central portions of the country. The formation of drylines is most common during the spring and summer months.

The boundaries are most often found running across Texas, Oklahoma, Kansas, and Nebraska. In simplest terms, drylines separate the warm and moist air coming up from the Gulf to the east from the hot and drier air originating in the Desert Southwest on the western edge of the boundary. The name dryline comes from the fact that this boundary simply separates moist air from dry air.

Storms that form along a dryline are known to produce large hail, high winds, and tornadic activity. These storms always form on the eastern flank of the boundary, within the warm and moisture-rich air.

The location of a dryline is important because forecasters can use it to pinpoint what parts of the region are most likely to see the potential of dangerous storms. It is easy for forecasters to lean on surface observations to find the precise location of a dryline. This location then helps forecasters predict where storms will ignite.

A stronger dryline inherently gives forecasters more confidence in where storms will first fire up. The drylines also serve as the guide that meteorologists use when issuing severe thunderstorm or tornado watches. In general, these advisories will be issued for areas east of the dryline boundary. Conversely, areas to the west of the dryline are typically in the clear.