The National Weather Service in Tulsa sent a damage survey team to Crawford County this afternoon, and they concluded that an EF-1 caused the damage. The tornado produced damage beginning 3 miles southwest of Figure Five, however, the total length of the damage path is still unknown at this time. The path width of the tornado was estimated to be around 300 yards, with the maximum speed around 100 mph.

This is a very dynamic complex of storms that blew through the area overnight. The main core of storms moved through Oklahoma, and eventually raced into Texas with an impressive cold pool of air. The cold pool is simply a build-up of rain-cooled air that tends to push the storms south.

Take a look at the archived radar image on the left from early this morning. This complex is known as a mesoscale convective system (MCS). They are typically nocturnal storm systems that feed on the low level jet around 5,000 ft. They tend to die off shortly after sunrise as the low level jet weakens due to atmospheric mixing. This intense bowing line is called a "line echo wave pattern", and they're known to produce damaging winds over 60 mph.

What I really want you to focus on are the circulations I have drawn in over the radar. These circulations are the reason the line of storms bow and create wind damage. On the northern end, you have a counterclockwise circulation, while the southern end produces a clockwise rotation. They help to produce an inflow jet that bows the line of storms. These circulations are known as "book-end vorticies".

Now take a look at the second radar image on the right. The counter clock wise circulation remained in tact through the early morning hours, which helped to fuel severe weather across eastern Oklahoma and western Arkansas. The eastern side of the circulation created enough low level wind shear to create a small tornado near Figure Five.

Without these important circulations, the storms would lack proper structure, and most likely die off.