I learned quickly after moving to the Midwest never to ignore MCVs or surface lows here. I observed two tornadoes in the St. Louis metro area today with supercells that fired in the southeast quadrant of a remnant MCV from last night's storms on the Plains. The MCV managed to entrain surface-based instability behind an earlier line of convection that cleared out by mid-afternoon.
I caught the first tornado at the intersection of Highway 370 and Earth City Expressway east of St. Charles. The wall cloud was wound up tight and produced intermittent vortices on the ground as it approached from the south. The tornado hit an area of industrial warehouses south of 370 with debris flying, then crossed the highway and eventually became fully condensed for a brief time. A Southwest Airlines 737 jetliner on approach to Lambert Airport passed directly through the tornado circulation, with the aircraft visibly rolling to the left briefly.
Rotating wall cloud and funnel with intermittent ground vortices crossing the Missouri River at St. Charles. The building in the background is the Ameristar casino next to I-70:
Tornado impacting warehouses south of Hwy 370:
Debris and ground circulation spray in field south of Hwy 370:
Southwest 737 jet and tornado debris:
Funnel beginning to condense north of Hwy 370:
Fully condensed north of Hwy 370:
I caught the second tornado between Highland and Trenton, Illinois with another low-topped storm. This tornado was never fully condensed, but had periodic ground circulations visible as debris/spray on the wet fields. It was essentially the size/intensity of a dust devil at the ground. Since this tornado was very weak, I approached it and let it cross within 10-20 feet of my vehicle. You can see the circulation move through the corn on the right side of the road in my dashcam video (linked above).
So far this year, I have seen twice as many tornadoes in Missouri and Illinois (6) as I have in the Great Plains (3).
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The following comments were posted before this site switched to a new comment system on August 27, 2016:
Nice! I just saw that on news 4. Watch for Cold Air funnels around lake of the Ozarks as that low isn't too far off. I've only seen one of those ever. - Posted by Tim
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