May 22 2008 chase



Departed KC at 830am with a rough target of Utica in westcentral KS.  Numerous supercells were likely to develop over the high plains as large scale ascent

overtook the dryline.  With a deep parent surface low, strong isallobaric adjustments would allow for relatively brisk and backed 0-1 km agl flow over western KS

and far southwestern NE... which is generally where the best tornado potential would exist.  I looked closely at the 12Z data, still debating over whether to

mess with the surface warm front close to the NE border... where low-level winds would have the strongest easterly component, contributing to hallacious shear amidst

CAPES AOB 1500 J/kg.  A little farther south, short-term model guidance was not agreeing on how significant the low-level shear would remain in an environment

with much stronger instability (CAPES around 3000 J/kg).  Based in part on the timing of when individual storms chose to produce tornadoes (and my own indecision),

the main tornadic show I ended up chasing was indeed farther south into the warm sector.  The 00Z DDC RAOB ultimately showed a perfectly sufficient (bordering on large!)

low-level sr-hodograph, which may actually be a slight underestimate of the shear available for my storm (~80 miles north of DDC).  I'm thus a little surprised that it

wasn't quite as productive as its friends farther northwest (each of which began tornadoing 15 minutes after I'd left them).  Still, I can't complain about what I observed,

as it was quite a treat and my best daylight tornadoes to date since 09/21/06.




Images (click for larger version)


327 pm: strengthening updraft with inflow band west of Dighton KS

337 pm: supercellular characteristics develop as storm starts to turn NNE

344 pm: cloud base lowerings southwest of Gove.  The storm developed a pronounced (if low contrast) wall cloud as it continued west of Gove, with very strong ESE inflow winds.  As it reached I-70, the storm turned more northerly and structure became messier.

456 pm: same supercell now turning NNW to the southwest of Hoxie KS.  Cloud base structure had just recently appeared to improve with a low-level meso/clear slot (as in photo)... interestingly, right at the time I was preparing to abandon it and commit to a beefier supercell developing well to my south.  While en route, I bypassed an intermediate and similarly pre-tornadic storm southwest of Grainfield on I-70; at the time it had a distinct, non-rotating wall cloud with a massive wall of rain encroaching behind it.

Taking Highway 283 south of Wakeeney and then the Trego-Ness county line gravel road 12 miles west, I intercepted my target storm about 6 miles northeast of Utica KS at 608pm.  I was initially surprised by the relatively high-based and linear structure.  However, as I headed north, rapid cloud base lowering beneath a classical RFD surge occurred immediately to my northwest (video only... captures forthcoming.)  Within minutes, a violently rotating low-level mesocyclone was born, with an impressive train of RFD-driven dirt blasting in front of it (615pm, as in photo... view looking NW).  The dark mass beneath the visible low-level meso contained a tornadic circulation intermittently during the next several minutes, which WFOGLD appears to have rated as EF-1 based on damage to a home and outbuildings.

615pm: same.  The structure in this scene was somewhat reminiscient of the Hallam NE storm during its first large tornado near Alexandria... four years ago to the day.
616pm: same.  Over the next couple minutes, the tornadic circulation became rain-wrapped while my attention was diverted to a new tornado.

626pm: the new tornado developed to the ENE on the forward lip of the meso (view looking NNE)... a classical area for anticyclonic spinups.  The tornado persisted for four minutes, with a fairly dramatic ropeout as the condensation funnel aloft tilted and a substantial shower of dusty debris formed at ground level (video only).

632 pm: a third tornado developed back to the west, behind the primary meso.  It lasted about one minute.

637 pm: while my attention had been diverted to the previous two tornadoes, the primary low-level mesocyclone rapidly re-emerged from the rain... larger and more low-based than before.  It had a rather incredible appearance as it began to cross the road in front of me.  The photo above shows my high-contrast view of the meso after it had passed my longitude.  Violent merry-go-round rotation suddenly ensued, and a dusty tornado occurred for a couple minutes beneath the leading (right-hand in photo) edge of the circulation.

642 pm: I turned east as a wet RFD surge rapidly overtook the low-level mesocyclone (and nearly my car, too)... obscuring the tornado.  I turned north toward I-70, and over the course of the next 10 minutes the storm transitioned into a typical HP supercell.

732 pm: same storm much later northeast of Hill City.  I dropped back south of Wakeeney and observed a final tornado at darkfall with a new storm passing over Trego center.  It was a truncated cone  around 8:48pm... lasting a minute or two just as that storm transitioned to an HP as well.



Maps, weather data


observed supercells


observed tornadoes (paths estimated)


21Z subjective surface analysis


modified 00Z DDC RAOB to represent Collier KS

Sfc T/Td: 81/64 F

MLCAPE: 2940 J/kg

MLCINH: 3 J/kg

0-3 km MLCAPE: 106 J/kg

MLLCL: 1381 m

MLLFC: 1491 m


modified 00Z DDC RAOB hodograph to represent Collier KS

storm motion: 204 deg @ 35 kts

0-1 km SRH: 297 m2/s2

0-3 km SRH: 348 m2/s2

0-1 km bulk shear: 29 kts

0-6 km bulk shear: 63 kts

7-10 km SR flow: 20 kts