Severe WX April 11th-13th, 2020 Severe Weather Threat

[Equus]

Yeaaaaah the 18z NAM does not want to play nice at all. Never fun being able to bring up a PDS sounding basically anywhere in the warm sector. STP is maxed out in a worryingly large area

Even worse, any morning convection/cold pool could lay out boundaries that make things even worse if advection is stronger than forecast (as is typical) - there's a fascinating thesis paper that I think of every time there might be early convection that laid out a case that the highest end corridor of violent tornadoes on 4/27 was enhanced by the morning convection boundaries. Assuming the environment has time to recover of course, but looks like we would have time to do it with the models continuing to slow

 

[warneagle]

The NAM has tended to be overly aggressive with these events at this range in recent years, but when it's basically in line with all of the other models...

 

[Equus]

It really is worrying when even the least aggressive models say a volatile environment not too much more pleasant than what the NAM is painting. Could always be random mesoscale factors to temper things but pretty confident someone somewhere is going to get a sizable tornado Sunday

 

[NWMSGuy]

 

[Bama Ravens]

 

[Equus]

18z NAM needs to be put in a time out until it can learn to play nice with Dixie Alley

 

[Kory]

18z Euro needs to be put in a time out until it can learn to play nice with Dixie Alley

I don’t have paid access to it. Can you describe what it’s showing? I’m assuming no major changes...

 

[Equus]

Oh wait, I meant the NAM lol sorry

 

[Kory]

Oh wait, I meant the NAM lol sorry

Dang I was excited. The 18z Euro is behind some paywalls that I just refuse to pay for right now.

 

[Equus]

Yeah same, out of my pay league. Ah well... here's to waiting for the 00z

 

[MichelleH]

I saw Fred's post on Facebook too and shared it. Feeling sicker and sicker about this.

 

[Bama Ravens]

I saw Fred's post on Facebook too and shared it. Feeling sicker and sicker about this.

Yeah. It is not to the same level, obviously, but when he posts like that it reminds me of his post on TW on the evening of April 26, 2011.

 

[tennessee storm chaser]

Yeah. It is not to the same level, obviously, but when he posts like that it reminds me of his post on TW on the evening of April 26, 2011.

if cape is even slightly under done, which most time models pick up on that last day or so... the sky may be the limit on this event... loaded gun soundings

 

[Kory]

We won’t have the CAPE of 4/27/11, but that doesn’t really matter. Whether you have 2000 J/KG CAPE or 3000, the storm will function the same in that modeled atmosphere. Any storm that can establish itself in the warm sector will pose a tornado threat.

 

[TornadoFan]

 

[TornadoFan]

I'm curious as to what "eject" means when it comes to lows and troughs.

 

[jmills]

I'm curious as to what "eject" means when it comes to lows and troughs.

Take this set up for example:



The low is still cut off over the Baja region of California. When this trough opens up and becomes progressive (i.e it starts to move east), it's said to "eject".

This is kind of a rough explanation but I hope it makes sense.

 

[Richardjacks]

Take this set up for example:

View attachment 2721

The low is still cut off over the Baja region of California. When this trough opens up and becomes progressive (i.e it starts to move east), it's said to "eject".

This is kind of a rough explanation but I hope it makes sense.

thank you, I couldn't have said it better myself.

 

[Kory]

I was able to sneak a peak at the 18z Euro. QPF streaks through AL (signature of supercells) through midnight. Looks like a long-duration event with supercells in the open warm sector and stuff popping along the dryline way west over MS into the later evening hours.

Warm sector looks untouched after the open warm sector supercells.

 

[Equus]

4/24/10 had pretty much the same deal, remember having a ridiculously long duration event... still seems like it could be similar