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Severe Severe Weather February 16th -18 2022

15z rap has lapse rates pretty high
this system has speeded up a bit as well it looks like lr75.conus.png
 
Just my opinion here. But I think we may actually see a substantial risk for a few longer track supercells, maybe tornadoes. Some of the limiting factors look like there are starting to turn around. There may even be breaks in the clouds during the day as well. Even if it is just around 1000-1500j it's still a good bit for a winter event. Although with the amount of shear you'd probably rather see 3000+. Temps look like they could reach near 70 and dewpoint not far behind. Hm. Really itching at the bit to see 18z convection models. That north Alabama / north Mississippi looks to be pretty volatile. I'd like to do a more detailed look later when I get home. But all hands should be on deck for a decent threat. I really think this could boom.
 
Arcc said:
That is 700mb to 500mb, the issue is the surface to 700mb.
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? I've always seen comments on the 700mb- 500mb mattering. I think from the 15z rap it was around 6.0 for surface up. which isn't great but isn't the worst. 18z hrrr coming out along with other models. Peek at what those show.
 
Zander98al said:
? I've always seen comments on the 700mb- 500mb mattering. I think from the 15z rap it was around 6.0 for surface up. which isn't great but isn't the worst. 18z hrrr coming out along with other models. Peek at what those show.
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pretty ugly area of warmth aloft esp at 700mb, with limited low level instability BCFA9433-3FD7-4C4A-8E56-2BA15E698FF3.png
 
Zander98al said:
? I've always seen comments on the 700mb- 500mb mattering. I think from the 15z rap it was around 6.0 for surface up. which isn't great but isn't the worst. 18z hrrr coming out along with other models. Peek at what those show.
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The GFS has low level lapse rates of 6.2-6.3 in some areas but cape and 0-3km cape is very low.
 
Myfrotho704_ said:
pretty ugly area of warmth aloft esp at 700mb, with limited low level instability View attachment 113608
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Wouldn't temps getting around in the high 60s low 70s be able to overcome that. Yeah that limited low level cape will limit tornado formation a good bit. Although I'd wait until HRRR came into range. I'd trust it most on forecasting the low level instability. Also peak those lapse rates fro above the surface to 3km. Theyve come up a good bit. ?
 
Arcc said:
The GFS has low level lapse rates of 6.2-6.3 in some areas but cape and 0-3km cape is very low.
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I'm going to wait until the HRRR gets in range. 18z comes out, see what it says on the low level instability and low level lapse rates. 18z should start rolling out here soon. I'f we get breaks in the clouds and sunshine. Those low level lapse rates are going to go up.
 
18z model only goes out to 12 o'clock Thursday with temps in the low 70s already. Very well may reach 75 in portions of Alabama and upper 60s dewpoint possibly. With a wide warm sector.
 
Huntsville afternoon AFD on this event



A risk for strong to severe storms continues, especially for our
more western areas. The main threats appear to be damaging winds.
Very high shear preceding the system, and somewhat higher model
produced instability keeps a tornado threat in as well. Am thinking
that a Quasi-Linear Convective System feature/squall line will bring
a higher severe threat. Models were trending more to a latter squall
line/frontal passage occurring more on Thu evening. High temperatures
on Thu, especially if more sun breaks through could rise to around 70
in a few spots (which could enhance the severe risk). Winds ahead of
the system especially Wed night into Thu evening could get breezy to
windy, with gusts over 35 mph possible Thu/Thu night. A Wind Advisory
may be needed if this trend continues.
 
Maybe a faulty thinking but... 500-850 sbcape seems very low for a 65 dewpoint. Something seems wonky about that. Usually they go up. Usually see 500-850 cape in a 55-60 dewpoint range. Saw 1000-1250 sbcape in a January tornado with a 60 dewpoint. That went on to produce a ef3. Just seems very wonky. And yes I know there isn't much sunlight, even so. It still seems low. Watch it slowly go up in future HRRR runs or something. Just doesn't sit right with me seems oddly low.
 
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Zander98al said:
Maybe a faulty thinking but... 500-850 sbcape seems very low for a 65 dewpoint. Something seems wonky about that. Usually they go up. Usually see 500-850 cape in a 55-60 dewpoint range. Saw 1000-1250 sbcape in a January tornado with a 60 dewpoint. That went on to produce a ef3. Just seems very wonky. And yes I know there isn't much sunlight, even so. It still seems low. Watch it slowly go up in future HRRR runs or something. Just doesn't sit right with me seems oddly low.
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It’s that low because there’s warm air aloft at 700mb and cloud cover, a cape killing combo, there’s reasons why in the summer sometimes there’s really high dews but poor SBcape, because there’s mid level warmth, also it’s the cool season
 
deltadog03 said:
Am I the only one really not impressed by this setup? The winds will be there for sure, but looks like WAAAAY too much shear and not enough cape and that is going to shred any updrafts apart quickly.
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Lol your not the only one I think fro and arc feel the same. Ive commented a few times on the storms being torn apart with little instability and very strong wind shear, but it's a winter event any tornado threat bears watching and I felt like this event could boom. I thought we would really need to hit 2000j to sustain anything but who knows. All these storms are going to be super wispy more and likely.
 
Well the 00z HRRR Is now hovering around 1000j of sbcape in MS/AL ?. Kinda lines up with my thinking earlier that it was too little currently. Still think it's a bit low but we will see. going to be a bunch of low topped supercells that's for sure.
 
Myfrotho704_ said:
Meh, this looks favorable more for a QLCS, highly forced and sheared. low level and mid level lapse rates aren’t really great at all, Hodographs are favorable for cyclic stuff if anything was to develop “out ahead” but the overall thermodynamics aren’t great and wind parameters aloft lean to more of a QLCS threat, nothing eye popping about this and looks like your typical cool season severe wx event. Still far out tho and prone to changes, globals typically decouple the BL to fast as well View attachment 113383View attachment 113384View attachment 113382
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QLCS it is haha
Zander98al said:
Hrrr shows a semi broken line of supercells rolling through bham at 5 o'clock. Here's updraft helicity through the final frame of 00z hrrr.View attachment 113633View attachment 113634
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Trends will be important to watch today. Winds are already starting to crank out of the south, I'f models underestimate moisture advection or cloud breaks it'll spell bad news. You'll more and likely see a enchanced risk tommorow for a chunk of missipi and portions of west Alabama
 
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