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Severe WX Severe Weather Thread - 6/15/26 - 6/18/26

Another lesson in short term forecasting. When things start downtrending last minute across multiple runs, the appropriate response is to take it at face value. It’s almost always a poor decision to start dismissing it as a fluke or one off, or start concocting a rationale in which a high-end outcome is somehow still likely. When the models do this, pay attention, because they are probably picking up on something. 3/15 was a learning experience, and this just reinforces it. The takeaway from both of those events is don’t cope-cast when things downtrend.
I did cope cast on 3/15, I'll admit it. But I remember your comment from a few events ago where you mentioned how people always bring up excuses to last minute downtrends. I didn't copecast today but for one thing, the models are very much right on downtrends. Just like how we take runs two days out at face value, take the last 06z/12z at face value. Does wonders to the last minute thinking.

A part of me feels that people subconsciously sometimes don't want to believe a last minute downtrend because they wanted a certain event to happen as it did and that's why they excuse the last minute downtrends.

I've always found using models day of for the 06z and 12z run is fine. But I don't use them after those runs. They're essentially the runs that determine the final thoughts on a day to me and this morning, that 12z was relatively unimpressive. Poor inversion, thermo issues, shear imbalance. I wasn't optimistic since this morning on this event

I always tell people when they bring up th "it's just one run" that the HRRR is usually always right on a downtrend the day of. Hopefully more learn to trust these type of signals
 
STP and VTP are actually reliant on LFC height. If LFC is high enough, both parameters will show up as 0, regardless of how good the kinematics are, usually because LFC height is closely correlated to how volatile the kinematics are anyways.
IIRC, that's LCL height, not LFC height. They're two very different things.
 
It blows my mind from the talks we were having just 36 hours ago. While we weren’t really comparing the outbreaks themselves to this. We were comparing more of the kinematics that were at play. 2026 continues to be a usual year. I don’t think there should be a rule. You won’t know it’s a big outbreak until the first couple storms write the story.
There should probably also be a rule about comparing events to super outbreaks / Palm Sunday the day before. It seems to happen many times per year here and it never pans out.

That said there is still a decent severe thunderstorm outbreak going on, and the tornado threat should increase a bit over the next couple hours.
 
Though that makes me wonder about cases where the models tend not to show much happening, only to start uptrending the day before/of. Perhaps start taking them at their word in that case...?
Actually yes, at least in terms of short term CAM trends. While there are exceptions, I can think of plenty of examples of last minute uptrends taking everyone by surprise, including one that unexpectedly resulted in an EF4, an EF3, and an EF2 tearing through the metro area I used to live in. That was a lesson to the contrary,
 
"guys, it's not over yet, why are we calling this a bust! Weenies"
Joker Clown GIF
 
LFC is more important as that’s the level where air parcels begin a free ascent towards the EL. That’s what storms care about.
LCL is simply where air parcels condensate.
What I meant is that the STP family currently make use of LCL height, but not LFC height, and I was suggesting adding LFC height to them. I'm sorry for any confusion that I may have inadvertently caused.
 
What I meant is that the STP family currently make use of LCL height, but not LFC height, and I was suggesting adding LFC height to them. I'm sorry for any confusion that I may have inadvertently caused.
Ah gotcha, I haven’t looked at the single parameters that make up those in years so I sort of forgot and got those two mixed up.
 
I did cope cast on 3/15, I'll admit it. But I remember your comment from a few events ago where you mentioned how people always bring up excuses to last minute downtrends. I didn't copecast today but for one thing, the models are very much right on downtrends. Just like how we take runs two days out at face value, take the last 06z/12z at face value. Does wonders to the last minute thinking.

A part of me feels that people subconsciously sometimes don't want to believe a last minute downtrend because they wanted a certain event to happen as it did and that's why they excuse the last minute downtrends.

I've always found using models day of for the 06z and 12z run is fine. But I don't use them after those runs. They're essentially the runs that determine the final thoughts on a day to me and this morning, that 12z was relatively unimpressive. Poor inversion, thermo issues, shear imbalance. I wasn't optimistic since this morning on this event

I always tell people when they bring up th "it's just one run" that the HRRR is usually always right on a downtrend the day of. Hopefully more learn to trust these type of signals
Oh to be clear I wasn’t referring to you or your forecasting when I made that comment. Zero cope-casting from your end in relation to this event. But yes, same sentiments here, when the CAMS show a dramatic short term shift, do not just write it off as just an outlier run or runs. We’ve had too many examples to ignore the fact that this usually means something when it happens.
 
Though that makes me wonder about cases where the models tend not to show much happening, only to start uptrending the day before/of. Perhaps start taking them at their word in that case...?
6/20/25 comes to mind. HRRR started to show 1-2 robust supercells in east ND the early morning of the event, which basically was exactly what ended up happening
1781739686445.png
 
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