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  • Andrew Pritchard

May 30 2015 | Outflow boundary enhanced supercells

Another marginal day, but on a Satuday in May - you chase. Overnight/morning storms had left an outflow boundary across central Illinois, very close to home actually. With high cape/low shear I had hoped that storms would interact with this boundary and perhaps briefly rotate.

This did end up being the case, but though they came close several times, no actual tornado touchdowns were observed.

SPC 8:00 AM Tornado probabilities - only 2%, but again on a Saturday in May, you give that a shot.

SPC Day 1 outlook at 8 AM with a Slight Risk over my target area:

I chased this one with my dad again - this time meeting at his place out in Sidney, IL. We lazily sat around for the early afternoon hours before a couple of interesting storms began developing to our south. Again, an outflow boundary was draped almost right along Interstate 74 in eastern Illinois. My plan was nothing more than to sit under this boundary and watch storms interact with it. The first cell did just that right around the St. Joseph area producing a very prominent funnel cloud that came about 1/2 way down. I was on the phone with the NWS for much of the funnel clouds life and only got a little bit of crummy video and a couple photographs that aren't a ton to get excited over:

Radar screen shot from shortly after 2 PM showing weak circulation in the storm just to our west.

2 PM base reflectivity on what was now a brief mini-supercell producing a funnel cloud near St. Joseph.

A second storm followed a similar path and hit the boundary in almost the same spot - this time in much more dramatic fashion. The second half of this video shows the storm quickly wrapping up before we are unfortunately surrounded by rain and pinned up against the Salt Fork River with no road options for getting back in front of what I think could have been a very brief/weak tornado touchdown in rural areas:

After this intercept we swung back by my dad's place in Sidney for a pit stop, and ultimately his final stop. I packed it back up in my car and went after one more cluster of storms that was approaching from the Monticello area. While some brief supercell features were observed, the storms were predominantly outflow driven and gusted out as I let them go near home.

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SKYDRAMA | Meteorologist & Atmospheric Photographer Andrew Pritchard

I'm a meteorologist born and raised in the American Midwest passionate about forecasting and observing severe storms.

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