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Multiple-tornado supercell of 16 May
On Tuesday, 16 May, VORTEX intercepted a supercell in SW KS that
produced at least four tornadic ciculations. We targeted SW KS
because we expected that region to be at the left side of a nose
of a strong jet, with the associated deepening of a surface low
and backing low-level winds. Further, it appeared that CAPE
would be best there because of the clearing of a thick cirrus
shield. We gathered a good "INIT" data set on a stationary
confluence line (and radar-indicated fine line) near Sitka, KS
(SSE of Dodge City) while we were waiting for the surface
features to evolve.
A storm formed near a cold front/dryline intersection near
Garden City late in the afternoon. It quickly became a
supercell and produced its first, large tornado near Garden City
before the surface armada arrived (but I think the two research
aircraft were already at the storm at the time of the tornado).
The surface armada arrived in time to observe a second, smaller
tornado just ENE of Garden City, extending from a very occluded,
weakening flank of the storm. The entire storm seemed to weaken
temporarily, and then reintensified in the vicinity of Kalvesta
where it produced at least one tornado. Several mobile mesonet
teams operated near that tornado.
The Kalvesta circulation, or a new one near it, moved to just NW
of Jetmore, KS. The surface armada deployed in a north-south
section of road north of Jetmore as the mesocyclone moved across
the highway about 6 miles north of Jetmore. This was a good
deployment, and included all mobile mesonet teams, turtles
deployment, and attempted soundings to assess the forward-flank
baroclinity.
However, this mesocyclone did not produce a tornado in the same
manner as the previous ones had. Instead, as the gust front
south of the meso surged over Jetmore, a circulation developed
on the gust front. Several teams passed under this gust front
in the vicinity of the developing circulation as we maneuvered
to get ahead of the storm. This was near sunset, the ciculation
was weak and elongated, and there were no suitable road options
for data gathering. Operations were officially ended.
Within minutes, the circulation intensified into a strong
low-level mesocyclone, and a tornado formed just southwest of
Hanston, KS. This tornado intensified and grew in size,
remaining on the ground for at least 30 minutes (perhaps 45 or
more) as it moved over open country south of Burdett and Rozel.
We obtained very exciting mobile scanning Doppler data of this
tornado, video from numerous angles, and mobile mesonet data
from one team that managed to stay ahead of the tornado. The
NOAA P-3 managed to continue collecting data during the tornadic
phase as they were providing communications support to the
armada.
This should be the most interesting data set collected so far
during VORTEX.
Erik Rasmussen
Jerry Straka