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Severe WX Severe Weather 4/11 - 4/15

buckeye05 said:
Yeah the presence of large cut nails instead of anchor bolts kept this one pretty low, but EF3 range isn’t egregious. I personally would have gone higher than 140 MPH given that the home was totally leveled and the joists/subfloor was dislodged though.
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Strictly for curiosity, what *would* it take for a tornado to rate EF4 with such a house (large cut nails)?
 
Grand Poo Bah said:
In mesoscale analysis it's the shear that's high and the helicity that's low?

It is really interesting how some of these cells are staying isolated despite their close proximity to others. Why aren't they merging?
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Remember, helicity is simply an updrafts tendency to rotate. The parameter itself isn’t directly connected to shear values.
It’s just that high shear tends to produce high helicity values. But it’s largely based on orientation of those shear values in the vertical within the lowest 3km. You can have very high shear magnitudes but helicity will be low if it’s all directional (vectors are in the same direction) rather than veered (vectors point in different directions).

These storms will mostly stay isolated despite the orientation of the shear vector favoring upscale growth and little capping is because the forcing mechanism (the diffuse short wave) is weak. You’ll have a messy storm mode but not a complete upscale mess.
 
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jiharris0220 said:
Remember, helicity is simply an updrafts tendency to rotate. The parameter itself isn’t directly connected to shear values.
It’s just that high shear tends to produce high helicity values. But it’s largely based on orientation of those shear values in the vertical within the lowest 3km. You can have very high shear magnitudes but helicity will be low if it’s all directional (vectors are in the same direction) rather than veered (vectors point in different directions).

These storms will mostly stay isolated despite the orientation of the shear vector favoring upscale growth and little capping is because the forcing mechanism (the diffuse short wave) is weak. You’ll have a messy storm mode but not a complete upscale mess.
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Same reason I believe why the last two events still produced even with overconvection.
 
TOR warning just south of Osceola, IA with a dozen storm chasers on it.
 
Aaron Rider said:
Strictly for curiosity, what *would* it take for a tornado to rate EF4 with such a house (large cut nails)?
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Essentially, there would need to be an obscene amount of anchoring nails to make up for the lack of bolts, and more violent contextual damage would also help. Homes can sometimes be rated EF4 even if there are nails instead of bolts, but the home leveled by the Union Center tornado appears to have long, wide gaps between the nails, leaving weak spots in the exterior walls. So that required extensive degree of nailing to make up for the missing bolts just isn’t there.

The 2022 Clarksville, TX tornado was given an EF4 rating based on a home that lacked bolts, but it was extensively nailed to its foundation. Large hardwood trees on the property were stubbed, debarked, and some were completely ripped out of the ground by their root balls and thrown. Vehicles in the immediate vicinity were lofted considerable distances and mangled, and the debris pattern was more violent as well.
 
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Anyone else having issues with GR Level 3? MKX hasn't updated for me since 4:29, ARX since 5:02, DVN and DMX wouldn't load any radar images at all when I tried to open them. I can see where the warning polygons are currently, but that's it. Radarscope on my phone is working.
 
CheeselandSkies said:
Anyone else having issues with GR Level 3? MKX hasn't updated for me since 4:29, ARX since 5:02, DVN and DMX wouldn't load any radar images at all when I tried to open them. I can see where the warning polygons are currently, but that's it. Radarscope on my phone is working.
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I've been tracking on KEAX and it is working fine
 
Yeah. They waited long enough to confirm it when it was obvious and AFTER it passed Clinton.
 
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