Tuesday, June 4, 2013
The El Reno tornado - unusual & very deadly
NWS released new information on Friday's tornado near El Reno OK, rating it EF5, and showing it to be a record width (2.6 miles). The map above shows the updated path, and the damage track from satellite (inset).
With the death toll now reaching 19 people, it was truly a dark and tragic day. I've been trying to make sense of what happened, and today's information along with a careful analysis of radar data offers some clues. The mesocyclone and tornado appeared to be "arcing" around a pivot point within the larger storm cell, and as it curved northeastward, it accelerated significantly. As some chasers have pointed out online, a simple analysis from conventional radar data of the movement of the storm-relative velocity couplet shows that the tornado, along with getting wider and more intense, increased it's forward speed from 20-25 mph to over 40 mph for a time (see speed annotations on the map above). This unanticipated movement may help explain why so many storm chasers were caught suddenly in the path, including the tragedy of Tim Samaras and his crew (see my prior post).
The map above also shows the location of 3 images that Shawna and I took while approaching the tornado and then moving south out of its way. The first image below shows the tornado in its early stages illuminated by lightning to our west-southwest:
This next image shows how hard it was to see the tornado at times, wrapped in rain curtains and poor contrast when it was about a mile to our west. This was truly frightening, and we high-tailed it to the south well out of its way.
This last image is from 2 miles south-southwest of the tornado when it was around 2 miles wide, looking like a large ghostly wall cloud on the ground:
I hope this tornado case forcibly reminds us that many tornadoes aren't always visible, and that they don't always move and behave the way we expect them to, even for the experts. Friday was a sad, scary day.
When I get time down the line, I'll try to post some more analysis about this case.
- Jon Davies 6/4/13