An Unusual Tornado Location

My blog back on November 5th talked about the possibility of tornadoes with that weather system. It did not produce a lot, but did produce one tornado in Oklahoma on the evening of November 5 and three tornadoes in southwest Missouri in the wee hours of November 6. The Oklahoma tornado was in a VERY odd location.

The National Weather Service has confirmed that an EF0 tornado occurred at the location shown below by the yellow triangle on the radar image at the time. It was about 2 miles southeast of Osage, Oklahoma, carving a 0.5-mile track that was about 75-100 yards wide. It rolled and demolished a mobile home and downed a number of trees.

What is most unusual is that the tornado was in that little green (low radar return) hole, BEHIND (west of) the leading line of strong rain. This was a storm that had turned into a mini-bow echo, that backwards-C shape. This kind of storm is known for damaging straight-line winds, and sometimes tornadoes along the LEADING EDGE of the rain, at the arrowhead I have drawn. That little rain-free hole is also very unusual in this kind of storm, where heavy rain usually occurs.

It turns out that this wasn't some fluke of noise in the pattern of radar return. The velocity pattern below for the same time shows a definite red-green velocity couplet indicating strong counterclockwise rotation -- upon which I've superimposed the radar outbound (leftward/westward) and inbound (rightward/eastward) winds. There is a black hole at the center of the circulation, which is probably the tornado! It was marked by a very turbulent signal in the radar return, sometimes indicative of a tornado.

The next figure is a slice through the storm, along the white line drawn over the first figure (above). The bow echo was even farther east aloft than at the surface, with rain falling downward and westward from the red storm core at about 15,000 feet -- which I've shown by the curved arrow. The tornado occurred at the T in that little low-level echo hole behind the bow echo. I have never seen anything quite like it!

The most remarkable thing about this image sequence is that it documents that Doppler radar detected a strong indication of a tornado in a very unusual location and circumstance. When I saw these radar images in real time, I was skeptical that a tornado could occur like this -- and had to mull over the whole scenario. But radar had detected the circulation about 5 minutes earlier and prompted the National Weather Service to issue a tornado warning. Before there were Doppler radars, I'm sure that no tornado warning would have been issued for this event.

Doppler radars are a great use of your tax dollars!