Hail close to the size of an actual baseball was spotted in Wellington, Texas

Hail pounded on the windows and strong winds whipped past a parking lot in Wyandotte, Oklahoma, on Monday around 1 p.m. local time.

Jessica Leigh Rice caught the moment on video.

"The [wind] was so strong that the water actually got in the first set of doors. It was crazy strong wind and hail and fast moving!" she wrote on Facebook.

Watch more:

Contrary to popular belief, overpasses are not safe places to seek shelter during tornadoes.

Overpasses do not offer any real protection from flying debris, and vehicles under them are at risk of having a tornado's winds carry them off.

Oklahoma Emergency officials warned residents that stopping under an overpass creates an even more dangerous situation:

Oklahoma Emergency Management says when people stop under an overpass, it prevents emergency vehicles from passing and it cuts off potential escape routes.

They encourage people to plan ahead and be somewhere that actually has a safe shelter.

Norman, Oklahoma, schools are closed today as the area prepares for possible severe weather.

"Out of an abundance of caution, schools will be closed Monday, May 20," the district said in a statement posted to their Facebook page. "Student safety is our top priority and we must make the best possible decision with the information we have available from weather experts to protect our students."

Tulsa also closed all of the schools in the district:

The city of Oklahoma City does not have public tornado shelters.

The city said one of the reasons for this is concern about traffic getting to public shelters.

Here's more on Oklahoma City's website: 

Being in a vehicle is one of the most dangerous places to be in a tornado, and risking a drive to a shelter during severe weather could be deadly. Many deaths attributable to tornadoes are attributed to being in a vehicle.
Traffic congestion from hundreds or thousands of other residents trying to get to public shelters could have tragic consequences.

Some airlines are already canceling flights into and out of Oklahoma City before the severe storms hit.

Will Rogers Airport said some airlines are waiving change fees and are urging travelers to contact their air carrier for more information.