Severe WX Severe Weather 4/24-4/26

[ColdFront]

Sunday is high end but I've pulled some soundings where it's confusing why models don't fire even globally. It's a high end environment easily, but convection not being shown is holding me back from saying anything further. The devil is in the details as always, just need to find what that "detail" is

Give me these types of set ups any day of the week. Better a blue sky cap bu$t than an over-convected slop fest.

 

[Clancy]

I think for Monday a higher threat area will eventually realize with a 30% inclusion for areas near central northwest Alabama north Mississippi and west Tennessee. Of course more changes to come but cips agrees with a higher area in that corridor, and I think the euro supports the idea.

The SPC thought as much and mentioned it in their discussion, pending greater certainty.

The severe threat should continue into Monday/Day-6 across portions
of the Lower Mississippi Valley. Strong storms should develop along
and ahead of an eastward moving cold front. MUCAPE of 2000-3000 J/kg
and 40-knots of deep-layer shear will support supercell
thunderstorms capable of all severe hazards. The location, number,
and intensity of these supercells will likely be modulated by the
events of Sunday. Specifically, if widespread convection does not
occur Sunday across the Southern Plains, a more robust reservoir of
CAPE/lapse-rates will be available to thunderstorms across the Lower
Mississippi Valley on Monday and a higher-end severe potential may
develop. This will be monitored in subsequent forecasts.

 

[Muwx]

I will say, we have seen so many cap bu$ts in OK the last few years, I am probably going to need to see full blown outbreak in that state before I actually believe in it.

 

[Kds86z]

I will say, we have seen so many cap bu$ts in OK the last few years, I am probably going to need to see full blown outbreak in that state before I actually believe in it.

 

[andyhb]

I will say, we have seen so many cap bu$ts in OK the last few years, I am probably going to need to see full blown outbreak in that state before I actually believe in it.

There have been more problems with early convective initiation in less favorable environments than cap busts, to be honest.

 

[Ozonelayer]

I will say, we have seen so many cap bu$ts in OK the last few years, I am probably going to need to see full blown outbreak in that state before I actually believe in it.

I thought OK was the home of early convection? Even then 5/18 wasn't too bad with the Arnett EF-3. Even this year we had a cyclic supercell with multiple strong-intense tornadoes.

 

[Muwx]

There have been more problems with early convective initiation in less favorable environments than cap busts, to be honest.

That's fair... that state just bu$ts in general in recent years, several cap related and several early initiation related. Its been a long time since a high end threat actually achieved anything close to the ceiling.

 

[Kds86z]

That's fair... that state just bu$ts in general in recent years, several cap related and several early initiation related. Its been a long time since a high end threat actually achieved anything close to the ceiling.

I understand what you’re saying. It’s hard to get it a daytime Oklahoma tornado event.

 

[Ozonelayer]

Not getting into the specifics, but the ongoing GFS has NEARLY 500-700 0-3 KM SRH and 50-60 knots of shear in Northern Oklahoma at 03z. If you blew out a candle the smoke leftover from it would be rotating in that environment

 

[US_Highway15]

Not getting into the specifics, but the ongoing GFS has NEARLY 500-700 0-3 KM SRH and 50-60 knots of shear in Northern Oklahoma at 03z. If you blew out a candle the smoke leftover from it would be rotating in that environment

Exactly. That's why I have that day circled. Yes, I fully understand that 100+ CINH isn't going to cut it, but it should be mentioned that we're only reliant right now on the GFS (which does have capping BIAS), GEFS, and Euro models. I'm still circling it until we get to looking at NAM, NAMNST, etc models.

 

[Clancy]

The signal for the Mississippi Valley into the Southeast in the April 27-28 timeframe is getting stronger by the day. GFS depicts strong EHI values of 2-3 over a wide swath of the Tennessee Valley up into Kentucky on Monday afternoon, with 40 kts bulk shear overlapping CAPE values of up to 3,500 j/kg. SRH values exceed 500 m2/s2 across much of Tennessee, Kentucky and parts of Alabama and Georgia. Low and mid-level lapse rates are favorable across much of the core threat area, thanks to late April thermodynamics. While there's still plenty of time between then and now, Monday definitely has my eyebrows raised.

@WesL I know you mentioned that local attachments are disabled due to stability issues - do we have a timeframe on when that might be restored?

For the time being, folks can use images either straight from the source websites or hosted on a site like imgur, but I imagine this could slow things down quite a bit during a major event.

 

[Kds86z]

 

[Muwx]

Stormnet with a pretty big downtrend for Sunday, specifically in OK, which is interesting. Still a long ways out so wouldn't read a ton into that, but also, stormnet has been pretty good this year.

 

[tennessee storm chaser]

MEG Memphis Nws latest saying latest hodos for mo day afternoon look long n curvy . Starting get their attention. Also mention cap 700. 800 mb

 

[Clancy]

Some very impressive values coming off the 12Z GEFS. Effective 00Z April 28. A wide swath of favorable parameter space forecasted Monday evening in the Deep South, from Louisiana through Mississippi and Alabama and into Tennessee, Georgia and southern Kentucky.

 

[KakashiHatake2000]

 

[Ozonelayer]

Shockingly, Trey doesn't seem to like Sunday as much as Monday. He says he doesn't like the dry air in some of the GFS Soundings but says that Monday has all the puzzle pieces of a more robust severe weather threat.

 

[Muwx]

Shockingly, Trey doesn't seem to like Sunday as much as Monday. He says he doesn't like the dry air in some of the GFS Soundings but says that Monday has all the puzzle pieces of a more robust severe weather threat.

Capping looks like a serious problem on Sunday at this range.

 

[ColdFront]

I will say, we have seen so many cap bu$ts in OK the last few years, I am probably going to need to see full blown outbreak in that state before I actually believe in it.

I’ve came really to the same conclusion.

Before everyone freaks out, I’m not poo pooing the upcoming plains threats or prognosticating on them. I’ll just believe a diurnal “upper end” tornado threat in Oklahoma when I see it.

 

[Ozonelayer]

Capping looks like a serious problem on Sunday at this range.

Oh definitely. But if the capping decreases (Especially with the capping bias of the GFS) then the ceiling is higher than any other theat this year. Monday also has a high ceiling but thats more or less dependant on if convection initiates on Sunday or not.

If convection initiates on Sunday: Sunday goes big, Monday goes lukewarm

If Sunday doesn't initiate convection: Sunday goes cold, Monday potentially goes big

Really just don't like that no matter which of the two happens, we have a solid shot of seeing a robust severe weather threat