What is the Dryline and What Does It Do?

For residents living in the Plains, the dryline is synonymous with violent spring storms and tornadoes; but what exactly is the dryline and how does it impact the weather?

During the spring and summer months, a rich flow of Gulf of Mexico moisture makes northward progress into the Plains. At the same time, strong warming from plentiful sunshine takes place over the eastern slopes of the southern Rockies. This very warm, dry air flows down the slopes into the surrounding Plains.

A boundary sets up where the dry, desert-like air meets the humid, Gulf of Mexico flow. This moisture boundary is known as the dryline.

On a typical spring day, the dryline takes shape over New Mexico and eastern Colorado during the morning hours, moving east into western Texas and Oklahoma in the afternoon and evening.

Dewpoints west of the dryline may fall to 20 degrees as gusty winds out of the southwest and west really begin to crank-up. Dusty conditions often result with reduced visibility. East of the dryline, sultry dewpoints in the 50s and 60s are common with southerly winds. The converging winds along the dryline cause the air to be lifted and under the right conditions, storms will form.

Dryline thunderstorms can develop rapidly and quickly turn severe. Very large hail, damaging winds and strong tornadoes are possible with these rotating storms known as supercells.

Whether storms do or do not form along the dryline often depends on temperatures in the middle layers of the atmosphere. Frequently, a very warm layer between 8,000 to 15,000 feet above the ground acts as a cap to building cumulus clouds, keeping a lid on storm development. If this cap can be overcome by the rising air from below, violent weather may result.

Dryline thunderstorms are most common from mid-spring into the early-summer months in what has become known as "Tornado Alley." At greatest risk is the area from western Texas to the Dakotas.

Be sure to keep WeatherBug active in your system tray to receive the latest weather alerts for your area as we enter the severe weather season.