2005: APRIL 11: NORTH KANSAS SUPERCELLS
|I was minding my own business on the way home to Indiana
when all of a sudden.... No, not really. I had all the gear running and
ready and was happy to see a field of vertical three o’clock cu in east
central Kansas along Interstate 70 by 17z. Today’s setup looked like a
slimmed-down and trimmed-back version of yesterday, a little less
instability, a little less shear, weaker and backed midlevel flow, but
with the same steep lapse rates and enough low-level shear and
sufficient LCLs to make it another interesting day. I found a great
long-lived storm, the Washington County supercell, which produced an
ominous, vacuum-cleaner style rotating updraft base and later unleashed
the single most bizarre and unexpected thing that has ever happened to
me while chasing.
Early in the day, I spotted an area of persistent towers northwest of Manhattan, and this became the Washington County storm. It produced several sustained wall clouds with varying degrees of rotation and finally organized itself dramatically between Greenleaf and Washington, Kansas, just south of state highway 36. Mike Hollingshead and I observed this storm as it snagged a boundary—either outflow or what I analyzed as a pseudo warm front in this approximate area—and anchored itself stubbornly, with an aborted split (with precip blowing northwest onto the newborn updraft, it didn’t have much of a chance), and propagation both to the south and the southeast. The southeast updraft grew dominant and Mike and I flanked it east, and observed the very low, carousel style updraft. The feature was composed of white condensation with tendrils that articulated the circulation. We were convinced it would tornado immediately. We perched on a hill and watched the storm wrap up again—the circulation tightened to an extremely rapid motion. I was stunned that there was nothing beneath. I haven’t seen that kind of rotation from such a low feature without a tornado beneath it. This was around 21z.
We chased this storm and its various moving parts across the Nebraska
border toward Odell, where we met up with Jonathan Garner and his chase
partner. For some time, our storm had served as the intersection for a
line of convection stretching to the northeast along the cold front, and
to the southeast along the not-so-dryline advancing from the southwest.
As this angle closed, convection approached from all sides. Our storm
had no hope of uncontaminated inflow and we determined as well that we
were nearly in the center of the surface low. XM streamlines confirmed
Nobody mentioned having seen circulation in the cloud base overhead
preceding the event. However, I don’t know that I was looking up there
anymore than I was looking elsewhere—it was a ragged, cold air storm
base the likes of which we’ve all seen. It was so benign in appearance
that none of us even had our cameras out, let alone recording at the
time. However, the sequence of the wind shift and the immediate precip
is fascinating to consider. Was this a very weak tornado? I don’t know;
I’m not trying to begin a debate. It was a vigorous circulation on the
ground, that much I can say with confidence.
Video grabs below