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Severe WX Severe Weather 4/11 - 4/15

I'm not greatly impressed about this period anymore due to several days having issues with CI. This is one of those times people will put down the CAMs for not convecting, even though there are very clear warm temps aloft and remnant EMLs all through. Things can change plenty but put it simple: don't be surprised if most of these days just simply fail to convect. I can see a window for a few but thermodynamically, this is hostile. Even the RRFS didn't convect on the warm front in the Midwest, and that's the supercell spammer of the decade
 
Grand Poo Bah said:
Oh look the 00z is out! and it's still there... Less than 100 hours out now, Don't love to see that.

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This sounding would not convect with such a sharp warm nose and dry slot accompanying that. I would not rely on analogs here, learning thermodynamically how environments are limited will help you a bunch in determining. This sounding would be favorable for photogenic supercells with tornado potential but have a look at that little "poke" in the 850 mb layer and how you have a dry slot accompanying that. When you have that sort of combo, storms get ripped apart when trying to develop. You would prefer a much weaker warm nose
 
Grand Poo Bah said:
The 18z GFS is getting real cute, though. That analog is so meta. I looked up the WFO that sounding was from. MGM stands for Montgomery, AL (now BMX)... So that's really interesting....

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I would disregard that 4/3/74 analog. That specific one pops up 3-4 times a season. MGM was well removed from any action on that day, same thing with JAN.

An 18z or 0z analog from that day from either DAY (Dayton Ohio) or BNA (Nashville TN) is what you’re looking for.
 
Grand Poo Bah said:
I read some literature the other day which said that during most outbreak sequences the majority of violent tornadoes (EF3+) occur in the second half of the sequence. This could help explain why the most tornado days are during phase 8, yet most violent tornadoes happen in phase 2.
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Somehow, that gives me a mental image of a typical outbreak sequence as basically building up to a climactic crescendo, what with that kind of backloading of violent tornadoes (assuming that research is indeed accurate).

ColdFront said:
I would disregard that 4/3/74 analog. That specific one pops up 3-4 times a season. MGM was well removed from any action on that day, same thing with JAN.

An 18z or 0z analog from that day from either DAY (Dayton Ohio) or BNA (Nashville TN) is what you’re looking for.
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I'd still imagine that the JAN/MGM soundings would probably be closer to something worthy of a Slight or Enhanced Risk as opposed to the High Risk-level soundings of BNA/DAY, and as such should be seen in that light.
 
I never got why in March you could get these huge tornado outbreaks with even just 50s dewpoints, but as you head later in the season large tornado days become less and less common even as dew points hit upper 60s and 70s as big troughs move through, and you eventually just get a smattering of tornadoes+damaging winds every other day...

I guess it might be higher wind shear early in the season?
 
12z NAM fired on Tuesday. I think down south in the Plains will likely be messy and as a result, stronger forcing will erode the cap. I could see the warm front in the Midwest convecting several messy, congealed cells on the warm front. NAM may be overdoing warmer temps aloft. Confidence now increasing in Tuesday, specifically for large hail and tornadoes in the Midwest.
 
Tuesday is my main focus right now. If the 12z NAM is at all accurate then a relatively potent environment could exist in the midwest, especially near the warm front for tornadoes.

Starting off with SBCAPE and MLCAPE, the latest NAM has both in the 3500-4000 J/kg range along/near the warm front, stretching to the IA/MO Border. I don't buy the warm air aloft being as severe as shown on it though. Low Level Shear is more than there, and shear vectors are pointing nearly directly to the east, aswell as backing from the south-southeast. If the scenario the NAM paints actually plays out, I wouldn't be at all shocked to see a scenario similar to 3/10 happen, maybe with less cells north of the warm front and cells having an easier time breathing due to the cap, and maybe more than 1 cell south of the warm front.

Will have to wait a little longer to say for certain, but if this trend keeps up on the NAM then it could be a long day for the midwest, especially Missouri, Iowa, and Illinois.
 
WeathermanLeprechaun said:
This sounding would not convect with such a sharp warm nose and dry slot accompanying that. I would not rely on analogs here, learning thermodynamically how environments are limited will help you a bunch in determining. This sounding would be favorable for photogenic supercells with tornado potential but have a look at that little "poke" in the 850 mb layer and how you have a dry slot accompanying that. When you have that sort of combo, storms get ripped apart when trying to develop. You would prefer a much weaker warm nose
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From my understanding, In situations with strong forcing and instability that warm nose and dry air aloft would be considered a "loaded gun", and greatly aid in keeping storms isolated. Given your expertise, do you think forcing will be strong enough to bu$t that cap Tuesday?

I also find it fascinating how often historic tornado days pop up in the analogs of these soundings. It just goes to show how classic those set ups were, and it's likely some extra factor that caused them to go over the top. I wonder how many times out of ten the exact main parameters 04/03/74 would go without cells firing as widespread as they did.
 
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Grand Poo Bah said:
From my understanding, In situations with strong forcing and instability that warm nose and dry air aloft would be considered a "loaded gun", and greatly aid in keeping storms isolated. Given your expertise, do you think forcing will be strong enough to Forecasted Convective Amplification Deficiency that cap Tuesday?

I also find it fascinating how often historic tornado days pop up in the analogs of these soundings. It just goes to show how classic those set ups were, and it's likely some extra factor that caused them to go over the top. I wonder how many times out of ten the exact main parameters 04/03/74 would go without cells firing as widespread as they did.
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The problem is that cap maintains itself the whole time so it isn't necessarily a loaded gun sounding. Talking from a discrete perspective, It's a loaded gun that remains the whole time that never fires. Also since it's more likely we'll see a strong QLCS from the forcing, this cap won't matter. I wouldn't see a situation where the storm mode breaks up
 
WeathermanLeprechaun said:
The problem is that cap maintains itself the whole time so it isn't necessarily a loaded gun sounding. Talking from a discrete perspective, It's a loaded gun that remains the whole time that never fires. Also since it's more likely we'll see a strong QLCS from the forcing, this cap won't matter. I wouldn't see a situation where the storm mode breaks up
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I see what you're saying now. Makes total sense. It does appear the 18z NAM has the cap eroding now. Assuming a 5-10 degree cold bias there'll be some pretty high cloud bases, but that SRH and Effective shear is something else. Took this sounding right by Des Moines, so I'm thinking it's probably time for me to get the word out to friends and family.

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