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July 15-20 Severe Weather


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That one in the article sure looked like a big funnel cloud (halfway down rule? ;))

I think the 1/2 down rule is probably too conservative, many examples now of tornadoes in which a ground circulation was detected by radar and followed > 5 min before there was any condensation funnel at all.

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Well the whole complex is moving SE, but the movement is so slow I'm not sure if it will ever get here. It's weird with the storms being aligned parallel to the movement.

lol I know. I've been refreshing the intellicast app on the ipad like crazy tracking its course.

Im guessing by 11 should see where its really heading. By 2am, hopefully should be knocking on the door. Nothing mean, maybe, but some rumble at least.

I wonder if there's a chance, it will eventually bow out during the night. Doubt it but who knows.

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I think the 1/2 down rule is probably too conservative, many examples now of tornadoes in which a ground circulation was detected by radar and followed > 5 min before there was any condensation funnel at all.

I have no doubt that is the case. I know as I was leaving the Quad Cities we were making more of an effort to teach rotation in the clouds above rotation on the ground = tornado, rather than focusing on the funnel itself.

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Good push coming on the western portion of the line now, running right down the instability gradient. Renewed outflow boundary evident too as this thing is trying to reorganize.

I wish I knew enough about meteorology to be able to tell things like this. To me, it looks like it's just going to sit stationary in C Wisconsin while it starts to weaken and dissipate.

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Good push coming on the western portion of the line now, running right down the instability gradient. Renewed outflow boundary evident too as this thing is trying to reorganize.

Original OFB is approaching middle Jackson County at this time, while the secondary, renewed outflow push is nearly coincident with the reflectivity gradient near Neilsville, Wisconsin. No wonder there are wind gusts being reported in Clark County now.

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lol I know. I've been refreshing the intellicast app on the ipad like crazy tracking its course.

Im guessing by 11 should see where its really heading. By 2am, hopefully should be knocking on the door. Nothing mean, maybe, but some rumble at least.

I wonder if there's a chance, it will eventually bow out during the night. Doubt it but who knows.

At the rate it's moving, it'll probably be here by 2 and in the Chicagoland area by 4 or 5.

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My guess is that, given that the cold pool seems to be growing, it will accelerate through the night.

I figured it would start moving a little faster. It can't move much slower than it is now. I think it's taken three hours for it to push the length of two counties from north to south.

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Not exactly. 6000+ CAPE and modest deep layer sheer usually = outflow dominance. If we had stronger deep layer sheer, there would be much better chances for sustained supercells. All the tornado/supercell parameters are being essentially saturated by the extreme instability and decent low level helicity, which isn't everything when it comes to supercells/tornadoes.

Oh you mean those HP giant blob cells.

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So, basically if we were in spring...

Or if there was more deep layer sheer... pretty rare to see this much instability in spring anyway. My point was that insufficient deep layer sheer is likely the culprit with respect to the linear outflow-dominat storm modes we are seeing. You could feasibly have 6000+ j/kg of CAPE and enough deep layer sheer to sustain classic supercells. Storm mode depends on more than CAPE alone, even when there is extreme instability.

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This could be a long-term wind damage producer as the cold pool that's beginning to help drive this acceleration establishes itself and this MCS continues to feast on the unstable atmosphere ahead of it.

SPC put out a new MCD that explained their thoughts that the surging area will probably swing around and affect the WI/IL border area and eventually Chicagoland early in the morning. Do you think the squall line will start moving more SE as the left (western) edge swings around. I can kind of picture how I think this will evolve.

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SPC put out a new MCD that explained their thoughts that the surging area will probably swing around and affect the WI/IL border area and eventually Chicagoland early in the morning. Do you think the squall line will start moving more SE as the left (western) edge swings around. I can kind of picture how I think this will evolve.

It already is. Loop the radar reflectivity from La Crosse.

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This could be a long-term wind damage producer as the cold pool that's beginning to help drive this acceleration establishes itself and this MCS continues to feast on the unstable atmosphere ahead of it.

Actually, it's really feasting on air to the SSW.

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Also, that HP cell on the east end of the line might be trying to transform more into a comma-head feature. The whole reflectivity return seems to be visually rotating.

I was going to note how it seemed as if there was already a MCV trying to form with that radar presentation.

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Or if there was more deep layer sheer... pretty rare to see this much instability in spring anyway. My point was that insufficient deep layer sheer is likely the culprit with respect to the linear outflow-dominat storm modes we are seeing. You could feasibly have 6000+ j/kg of CAPE and enough deep layer sheer to sustain classic supercells. Storm mode depends on more than CAPE alone, even when there is extreme instability.

I meant that you usually don't see that kind of deep layer shear during the summer, unless there is a rather strong storm system in the area.

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You can see on the MD graphic the convergence zone that lies across WI/IL, with SSW-SSE winds at Monroe, Madison, La Salle/Peru, and Bloomington/Normal, with SE-E winds at O'Hare, Lansing, and Milwaukee. The MCS will likely focus along that axis, with convection probably on 50mi either side of it.

mcd1666.gif

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You can see on the MD graphic the convergence zone that lies across WI/IL, with SSW-SSE winds at Monroe, Madison, La Salle/Peru, and Bloomington/Normal, with SE-E winds at O'Hare, Lansing, and Milwaukee. The MCS will likely focus along that axis, with convection probably on 50mi either side of it.

mcd1666.gif

Yeah, that convergence line likely signifies the quasi-warm front/instability gradient apparent in mesoanalysis.

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You can see on the MD graphic the convergence zone that lies across WI/IL, with SSW-SSE winds at Monroe, Madison, La Salle/Peru, and Bloomington/Normal, with SE-E winds at O'Hare, Lansing, and Milwaukee. The MCS will likely focus along that axis, with convection probably on 50mi either side of it.

Decaying lake breeze boundary...

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