How the Dry Line Impacts Severe Weather in Texoma

Wide spread drought conditions across western Oklahoma and Texas have given Texoma relatively quite severe weather

seasons over the last five years. Skywarn 6 Chief Meteorologist Ken Johnson tells us that this year may be a little

different.

Severe weather season in Texoma typically starts in late March and can last into the month of June. Changes

are occurring during this time of the year and it's this change that creates big storm systems which can spin

off severe storms and tornadoes.

Spring time storm systems draw in warm moist air from the Gulf of Mexico and hot dry air from the west. The boundary

where these two air masses meet is known as the dry line. The dry line can touch off thunderstorms that can become

severe and produce tornadoes. This is a feature we commonly see in Texoma. However, the position of the dry line

hasn't favored much of this for us over the last five years. The exceptional drought could be the reason why.

My good friend, Gabe Garfield at the National Weather Service in Norman, Oklahoma has done a lot of research on this subject and says, "the drought can impact the dry line. Where you have a lot of rainfall, that air is going to be a lot more moist. So the dry line will have a harder time moving past this moist air."

Garfield says this played a key role in the deadly tornado season that impacted central Oklahoma in 2013.

"There was a lot of moisture over central Oklahoma and the air over western Oklahoma and western north Texas was a lot drier.

Where you had the boundary of a lot rain and a lot of dry weather that was where the dry line tended to set

up."

In 2013 thunderstorms develop along that dry line in Texoma. As they tracked northward into central Oklahoma, they

matured into powerful supercells and produced tornadoes. One of these was the tornado that struck Moore, killing 24 people.

The summer and fall of 2014 brought a surplus of rain from northern Mexico into western Texas. While Texoma didn't see

a large surplus of rain, we did see more rain than in years past. The added soil moisture could mean more

vegetation. This can actually help give us more moisture.

Garfield has also noticed these trends. "Soil moisture comes into play here.  How deep does that water go into the soil? If it goes deep enough and

you start getting that vegetation, that starts the process of what we call evapotranspiration, where the plants

give off water and give that to the atmosphere."

This year's growing winter wheat crops could be a sign of added soil moisture.

The added moisture may cause the dry line to set up further west as we get into the storm season. If that occurs,

we could see better chances for storms to form further west, maturing into supercells as they move into Texoma. This could

also increase the chances for tornadoes.

This winter has gotten off to a good start with a rainfall surplus in the month of January. This added moisture now

could be used by future thunderstorms and could help put a dent in the ongoing drought.

For Skywarn 6 Weather, I'm Chief Meteorologist Ken Johnson