June 5, 1999

Lone Pine/Atkinson Tornadic Supercell


 ETA 12 h Forecasts VT 0000 UTC Sunday 6 June

Gonzo pattern in Nebraska. Boundary set up on Nebraska/S. Dakota border. Progs indicate lowlevel jet in same vicinity, as well as 3000-4000 J/kg CAPE, SREH>200 m2/s2, left front quadrant of incoming 250 mb jet streak, 500 mb winds >50 knots. Progged hodographs look violent tornadic. SPC has High Risk with enhanced wording.

What could go wrong?

Jet streak comes in late. Region stays suppressed in right front quadrant till near sunset, when monster storm forms near Lone Pine. I was with Al Moller, Mike Foster and others playing the boundary in S. Dakota.



We did drop down about 1 hour before sunset and did intercept the tornadic supercell before it produced two tornadoes. But, we were victims of the road system, and were not able to make it to updraft/mesocyclone...and had to let it come to us, long after it produced the tornadoes.



Lone Pine Supercell at Sunset

View looking west. Note "stingers" entrained into updraft core.

Base faintly visible.


 Atkinson Mesocyclone 15 minutes After Tornadoes

(Note: after sunset. Image has been heavily Gamma corrected).

Nice mothership with wall cloud. Headlights represent the leading vehicle of a HUGE chaser convergence.


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