A truly devastating tornado hit Moore, OK today at around 4:25 and I was tracking it on Live 11Alive Radar. As it went into the heart of Moore I quickly realized how bad it was going to be. Most of the time when cities get hit by tornadoes the radar signature doesn't change, in other words the hook echo remains the same. In some of the stronger tornadoes you can see a debris ball. What that debris ball is is shingles, 2x4's, windows, trees.... all of that flying around the center of a tornado... In this tornado the debris ball actually expanded as it went into Moore..... The tornado grew and started flinging debris around it as it expanded to 2 miles wide!!!! That is how large the debris ball was, it was 2 miles wide!!!!

Please say a prayer tonight for the folks in Oklahoma who lost everything today.

What you are looking at above is called a RFD, or a rear flank downdraft! It is the sheets of rain that is wrapping around on the right hand side of this tornado. What that is is a burst of rain that is very cold that wraps around on the back side of a rotating wall cloud. It is, essentially, a mini cold front that heps to increase the wind in the inflow to a wall cloud. It is like when you stick your finger over a hose, the area the water has to go through gets smaller so through conservation of mass and momentum you must increase the speed of the stream! Same with a rotating wall cloud and an RFD,t he RFD wraps around and channels the inflow making it go faster to give that final bump in the wind speed that the storm needs to form a tornado. The perfect balance between RFD and inflow is what makes long tracked tornadoes..... When the RFD gets wrapped up, the cold air will choke off the inflow and the tornado will die...