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Severe Weather Threat 4/27-4/28


A dangerous scenario is setting up today. Im particularly worried about the zone I circled in pink, it’s apparent a narrow corridor of extreme kinematics is setting up along the boundary the MCS system is leaving behind. This area is where the jet streak translation speed of 40knots is occurring and is experiencing the strongest forcing from the shortwave to the west. Literally any storms that travels across this area has a genuine long track, intense tornado producing potential.
This is also a perfect environment where multiple supercells can train along the same area multiple times. The latest hrrr shows this occurring, waiting for additional cams to come in.
VTP are already up to 6 near the tail end of the boundary at 9am…

The zone I circled in red, is where cape values will exceed 5000j/kg, and while again shear magnitude is lower here, the LLVWP is decently veered and SRH values will exceed 300 despite the lower shear magnitude.
Really, the only failure mode I see for both zones is that storms congeal and crowd themselves to oblivion.

The lower area would fail due to lack of convection and not overconvection. There's very little forcing down there, particularly in Arkansas, although CAMs have shown a slight uptick overtime in initiation around there.
 

A dangerous scenario is setting up today. Im particularly worried about the zone I circled in pink, it’s apparent a narrow corridor of extreme kinematics is setting up along the boundary the MCS system is leaving behind. This area is where the jet streak translation speed of 40knots is occurring and is experiencing the strongest forcing from the shortwave to the west. Literally any storms that travels across this area has a genuine long track, intense tornado producing potential.
This is also a perfect environment where multiple supercells can train along the same area multiple times. The latest hrrr shows this occurring, waiting for additional cams to come in.
VTP are already up to 6 near the tail end of the boundary at 9am…

The zone I circled in red, is where cape values will exceed 5000j/kg, and while again shear magnitude is lower here, the LLVWP is decently veered and SRH values will exceed 300 despite the lower shear magnitude.
Really, the only failure mode I see for both zones is that storms congeal and crowd themselves to oblivion.

Edit: had to reupload since this site is really getting bad at loading any images at all.
 
The lower area would fail due to lack of convection and not overconvection. There's very little forcing down there, particularly in Arkansas, although CAMs have shown a slight uptick overtime in initiation around there.
Most cams actually seem to unzip the dryline pretty fast and by nightfall where the LLJ peaks the storm mode along it is pretty clustered and messy.
Obviously doesn’t necessarily decrease the threat but it’s a trend to be watched.
 
I think a CIG3 for tornadoes should at least be considered, if trends look to continue to move in a dangerous direction. I don't support an upgrade to a high risk because that would require a 30% and that would require much higher confidence, but based on these shear values overlapping these instability profiles, violent tornadoes aren't off the table at all. I think we'll see at least one tornado capable of violent damage today.
 
Safe to say that the crapvection won't be out of St Louis by noon. Will be interesting to see how that affects the setup today (if at all).
St Louise isn’t being impacted by the MCS, it’s a bit ways north of them. And looking at current trends, the MCS will miss them to there north entirely.
Looking at visible, it’s already beginning to clear out. One would hope a scenario occurs where the storms later today overcrowd themselves, as that’s a real possibility. Fingers crossed.
 
Satellite, still lots to work out but there's evident clearing right now.

With a fast jet working to clear out morning convection, a highly volatile event today is appearing likely. Long track, intense tornadoes, and perhaps even one or two violent are a major possibility. Already reaching the 70s in Missouri at the moment and the more this cloud cover/leftover convection clears out, you have a highly dangerous situation.
 
Is anyone else concerned that the southern end of the system will overperform from what they're forecasting and the public won't be prepared because local mets have been downplaying it? Could just be because my nerves are raw today, but I just can't shake that feeling.
Still slightly perplexed that they haven't brought the 5% and 10% at least a little further southbound. Unconditional threat might not be as high, but anything that gets going during the evening hours would have lots of room and intense kinematics to work with.
 
St Louise isn’t being impacted by the MCS, it’s a bit ways north of them. And looking at current trends, the MCS will miss them to there north entirely.
Looking at visible, it’s already beginning to clear out. One would hope a scenario occurs where the storms later today overcrowd themselves, as that’s a real possibility. Fingers crossed.
Not only this, but as others have mentioned, it's pushing out an OFB directly into the STL metro area
 
Satellite, still lots to work out but there's evident clearing right now.

With a fast jet working to clear out morning convection, a highly volatile event today is appearing likely. Long track, intense tornadoes, and perhaps even one or two violent are a major possibility. Already reaching the 70s in Missouri at the moment and the more this cloud cover/leftover convection clears out, you have a highly dangerous situation.
STP based solely on the lowest 500meters are already up to 6 at merely 10am. Honestly not feeling very good about this.
 
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