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Severe Weather Threat 4/28-4/30

Genuinely the biggest Forecasted Convective Amplification Deficiency I think I can recall in all my years of tracking!

And It makes me super glad to say that. Environment was highly favorable across MN/IA/WI, yet ended up that despite getting convection none of it was robust surface based convection that could take advantage of it, hence just 2 tornado reports!

If anything, events like these are more interesting when you try to figure out what went wrong.
 
UK_EF4 said:
Genuinely the biggest Forecasted Convective Amplification Deficiency I think I can recall in all my years of tracking!

And It makes me super glad to say that. Environment was highly favorable across MN/IA/WI, yet ended up that despite getting convection none of it was robust surface based convection that could take advantage of it, hence just 2 tornado reports!

If anything, events like these are more interesting when you try to figure out what went wrong.
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And couldn’t even get anything significant in Oklahoma after dark, or Anywhere else..
 
It was also definitely not the linear aspect. Isolated supercells completely failed to do anything despite plentiful time and energy, even the QLCS formation failed to produce, I really wonder made today so pitiful.

Maybe lost data from missing soundings mangled the model output? Such a weird day.
 
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Just gonna repost this to help people understand what “went wrong”.

The surface wind vector being directional to the LLJ has caused almost every supercell along the dryline to be outflow dominant.

Couple this and the PBL wind vector having parallel orientation with the jet streak, which is responsible for the immediate upscale/linear convective mode.

The warning signs for this were present pretty much since the cams got into range, the fail modes have already been discussed.

But another particular red flag was that even when cams started convecting the dryline, none of them modeled impressive updraft helicity streaks.

Which can mean two things, anemic updrafts, or updrafts simply not taking advantage of the kinematics they’re in.

The unimpressive streamwise vorticity present on the hodographs alludes to these supercell’s inability to entrain background helicity into their updrafts due to the directional shear.

Today had a potential high ceiling, but the surface low responsible is simply ejecting to fast for the surface winds to back/veer enough to actually get any competent helicity entrainment.
 
Justin Hindman said:
I will say, the HRRR 24 hours before this event showed a line like what happened last night. It had an isolated cell in north central Iowa with no tornado streak. HRR has been on fire lately.
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Most cams modeled an unimpressive event.

Not a single one showed impressive updraft helicity streaks once they finally realized there was going to be convection because the low level wind vector was directional to the LLJ.

Just not going to get supercells to produce many tornadoes at all when that’s occurring. Instead you’ll get an outflow dominate mess, which is exactly what happened.

Obviously the upscale growth didn’t help either.

Moderate risk was the right call from a kinematic/parameter perspective, which is why the SPC went with it in the first place.

But I’m certain the forecasters there knew this b$st was the most likely outcome due to these reasons.
 
jiharris0220 said:
Most cams modeled an unimpressive event.

Not a single one showed impressive updraft helicity streaks once they finally realized there was going to be convection because the low level wind vector was directional to the LLJ.

Just not going to get supercells to produce many tornadoes at all when that’s occurring. Instead you’ll get an outflow dominate mess, which is exactly what happened.

Obviously the upscale growth didn’t help either.

Moderate risk was the right call from a kinematic/parameter perspective, which is why the SPC went with it in the first place.

But I’m certain the forecasters there knew this b$st was the most likely outcome due to these reasons.
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Exactly this. Its hard/rare to get a tornado outbreak, its VERY rare with speed shear only/lack of backed surface winds.
 
Just got back to campus.

Wanted to say that from a chasers perspective, yesterday had to be probably one of the worst days a storm chaser could've ever experienced. One of the obvious reasons being due to having of the biggest busts the SPC has probably had in years. However, outside of that, apparently some civilian kept on calling in *false* reckless driving reports on storm chasers. So you had numerous officers pulling over storm chasers. Was listening to the scanner and it was just false alarm after false alarm.

On top of that, it was one of the most crowded chases I personally have ever experienced, which made traffic/driving towards storms a nightmare, especially since you would have the lead vehicle at times traveling at 60 MPH, "trying" to catch up to the storm moving at 50-55 MPH.

Overall, was just a nightmare, and an unbelievably frustrating day to be a storm chaser in Iowa.
 
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