18 April 2002 - late night "elevated" nontornadic
supercell in north central Kansas by Jon Davies
On the night of 4/18/02, thunderstorms reformed in north central Kansas north and east of
a wave on a stationary front, after supercells earlier in the evening had dissipated in
central Kansas. After midnight in the early morning hours on the 19th, one of the storms
became a supercell with strong rotation on radar in Lincoln and Ottawa counties of north
central Kansas, prompting a couple tornado warnings. No tornadoes occurred, but 1.75"
hail was reported.
< surface
map 07 UTC
< ICT
radar base refl. 0618 UTC and 0708 UTC
This storm was in a "very elevated" environment north of the surface front, as
can be seen by the RUC-2 profile for Salina at 07 UTC, which shows no CAPE for parcels in
the lowest 100 mb. Parcels that yielded CAPE for this profile were around 750-700 mb, well
above the boundary layer. With more than 50 kts of deep layer shear interacting with the
updraft, this storm was able to produce large hail. But with such a stable profile in
low-levels, the tornado potential with this strongly elevated storm was very low:
<Salina
KS RUC-2 analysis sounding 07 UTC
Using SPC graphics around 07 UTC, the elevated CAPE not far to the south can be seen,
along with notable 0-1 km EHI in southern Kansas within a capped environment where no
storms occurred. But the large CIN (> 200 J/kg) in central Kansas to south of the front
with high LFC heights (around 3000 m and higher) confirmed the elevated environment across
Kansas on both sides of the front:
< 07
UTC most unstable CAPE
< 07 UTC 0-1 km EHI
< 07 UTC
LFC height
< 07 UTC
CIN & Sig Tor Parameter
< 07 UTC LFC height
When there is no CAPE to be found using any parcels from the lowest 100 mb of a profile,
this suggests that the environment is very "elevated", with storm buoyancy and
primary inflow coming from well above the boundary layer. In such cases, experience
suggests that tornado potential is very low.
- Jon Davies 7/1/02
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