Severe WX March 21-23 2022

[Taylor Campbell]

The newest 00z EURO run looks more similar to the 00z GFS.

 

[tennessee storm chaser]

Models don't differ on the instability axis and extreme shear axis being in conjunction with one another. I anticipate a 30 risk area in the new Day 5.

Bingo , and you are correct . Now a day 5 large 30 percent area

 

[JPWX]

Last 30% Enhanced for both Day 4 and 5 was April 29th, 2017.

 

[CheeselandSkies]

First sniff of the NAM (always suspect) for Monday has some nasty forecast soundings across parts of Texas...but there does appear to be some disconnect between the best SRH and instability.

 

[warneagle]

Last 30% Enhanced for both Day 4 and 5 was April 29th, 2017.

That was the Canton, TX EF4, for those who don't recall that date

 

[Taylor Campbell]

ZCZC SPCSWOD48 ALL
ACUS48 KWNS 180901
SPC AC 180901

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0401 AM CDT Fri Mar 18 2022

Valid 211200Z - 261200Z

...DISCUSSION...
Medium-range global model output -- both deterministic and ensemble
-- continues to indicate a multi-day severe weather event that will
progress eastward from the southern Plains Day 4/Monday to the
Southeast Day 6/Wednesday. The risk will stem from an upper
trough/low that will emerge from the western U.S. into the central
and southern Plains Monday. On Tuesday, models forecast a large
upper cyclone moving slowly across the Plains toward the Mid
Mississippi Valley, and then gradually elongating in a positively
tilted manner as it slowly impinges on the Midwest.

As a surface low develops over the northwestern Texas vicinity on
Monday in conjunction with the advance of an upper low, low-level
southeasterlies ahead of the cold front will advect Gulf moisture
across southeastern and into eastern Texas. As the initially stable
boundary layer moistens, surface-based CAPE is forecast to gradually
increase, supporting thunderstorm development which should persist
through the evening and into the overnight. With strong
southwesterly mid-level flow spreading atop the low-level
southerlies/southeasterlies, shear will support organized/supercell
storms, with an all-hazards severe risk including a few tornadoes
expected.

As the cold front advances from East Texas late Monday and early
Tuesday, toward -- and eventually across -- the lower Mississippi
Valley, a similar overall pre-frontal thermodynamic and kinematic
environment is expected as existed Monday, farther west. As the
moistening low-level airmass contributes to ample mixed-layer CAPE,
and strong/veering flow with height overlaps the instability,
severe/supercell storms are again expected. Potential for a few
tornadoes remains evident, along with hail/wind risk, centered over
Mississippi and extending into Alabama, particularly into the second
half of the period.

Risk should spread eastward across Alabama into Georgia Wednesday,
though with stronger ascent becoming somewhat removed from the more
favorable thermodynamic environment, overall severe risk may be a
bit lower than prior days. Still, potential for severe weather --
including supercells -- still appears a reasonable expectation, and
thus will maintain 15% probability into Georgia and the Florida
Panhandle.

As the front nears, and then likely reaches, the southern Atlantic
Coast rather early Thursday, degree of risk appears at this point to
likely remain limited before the boundary moves offshore. This
should mark the end of this multi-day severe-weather episode, with
Friday severe potential appearing minimal at best, at this time.

..Goss.. 03/18/2022

 

[tennessee storm chaser]

Seems euro slowly trending toward a gfs solution next week. Euro has much better warm sector also further north … bears watching for sure

 

[Fred Gossage]

Other models are inching closer to the GFS idea of better moisture recovery, but it's going to be a close call with the surface flow so sharply southeast. This isn't the Plains. A sharply southeast flow here means you're advecting from Georgia, the Carolinas, and the cooler west Atlantic... not from the warmer parts of the Gulf of Mexico. That will have to be a thing we need to watch. But even assuming the GFS is face value correct with moisture recovery and instability, or even underdoing it a bit, there is still a big issue with mid-level moisture being prevalent and how that would aid in easy widespread convective initiation instead of a cleaner storm mode... and then the meridional deep-layer flow would support a predominantly non-linear storm mode and storms raining out into adjacent updrafts. That doesn't mean we can't squeeze out a couple of sustained discrete storms ahead of everything that has significant tornado potential. That also doesn't mean we can't have an intense QLCS with widespread wind damage/QLCS tornado potential. GFS at face value has a serial derecho type feature initiate back in west/northwest MS and race northeastward across north central AL and middle TN. However, even if the GFS is not only right with the idea of moisture return but even hypothetically underplaying it, there are still multiple mitigating factors on even the large scale, much less smaller-scale details, that would put the ceiling for this event below "tornado outbreak", "violent tornado outbreak", etc.

That is all specifically for the Tuesday portion of the risk. I have a not-so-good feeling about the Monday threat back in Texas, since that area will be closer to the EML source region with steep lapse rates and drier air aloft, and having a sharp southeast flow there actually sets up low-level advection right from that reservoir of low/mid 70 dewpoints in the northwest Gulf. SE surface winds in Texas ≠ same outcome as SE surface winds in Mississippi and Alabama.

 

[Fred Gossage]

Synoptically speaking, the setup for Tuesday reminds me a lot of April 13-14, 2019. That ended up being a significant severe weather event, with several tornadoes... a few of them strong, and there were some fatalities. But like I think this one may end up as, that ended up being a grungy and messy storm mode, and not nearly the OMG that a lot of people thought it was going to end up being. I could easily see there needing to be an eventual Moderate Risk for wind and/or tornadoes on Tuesday across parts of Dixie. There are just larger scale limiting factors that would pull it away from being a full-blown tornado outbreak, and they are factors that it would take having an entirely different large scale setup altogether in order to "fix".

 

[Austin Dawg]

That is all specifically for the Tuesday portion of the risk. I have a not-so-good feeling about the Monday threat back in Texas, since that area will be closer to the EML source region with steep lapse rates and drier air aloft, and having a sharp southeast flow there actually sets up low-level advection right from that reservoir of low/mid 70 dewpoints in the northwest Gulf. SE surface winds in Texas ≠ same outcome as SE surface winds in Mississippi and Alabama.

I'm not feeling too good about it either. It's way too close to our area which rarely has the threat of significant tornadoes. Looking at the models it really looks to be firing right over my head and then traveling east. The storms usually fire just to our north or east and move on east forward from there so we're really not used to having tornado storms right here in the specific area. Now significant hail storms are another matter. We usually have two or three around here every year I had to replace my roof last year from one

 

[Equus]

D3 Enhanced for eastern Texas, and D4 30% seems to have been spatially expanded and encompasses parts of W AL now

 

[Clancy]

D4 disco is using the O-word.

...SEVERE WEATHER OUTBREAK POSSIBLE ON D4/TUE...

...DISCUSSION...
Latest deterministic and ensemble runs of the medium-range global
models continue to depict likelihood of a continuation of
potentially substantial severe-weather event across the central Gulf
Coast states Tuesday and into Wednesday. This includes a reasonable
probability of a regional-type tornado outbreak centered over
central and southern Mississippi for Tuesday.

 

[JPWX]

If both Monday and Tuesday's threat gets upgraded to Moderate Risk (in which I believe there's a good possibility they will be), it would be the first back to back March Moderate Risks since March 26th and 28th 2017. Also since the addition of the Enhanced Risk from SPC, this is the first Day 3 Enhanced for Texas in March.

 

[CheeselandSkies]

Now the 12Z NAM reaches Tuesday evening, and shows nil SBCAPE over a good chunk of SPC's 30% area despite dewpoints reaching the 60s...just bizarre.

 

[tennessee storm chaser]

Now the 12Z NAM reaches Tuesday evening, and shows nil SBCAPE over a good chunk of SPC's 30% area despite dewpoints reaching the 60s...just bizarre.

Nam being nam… it won’t be in its best till another 24. 36 hours

 

[Equus]

Lapse rates not ideal but hard to tell for sure this far out; may not be an issue as we get close to the event

 

[DetectiveWX]

Over on Southern WX: one analog brought up is the MS Delta outbreak of 1971 that killed 122 people. That happened in a La nina, too.

 

[CheeselandSkies]

NAM also appears to have some sort of secondary surface low or mesolow tracking from northern LA to northeast MS Tuesday afternoon/evening...this could make the threatened area smaller; but very dangerous.

 

[Brice Wood]

Over on Southern WX: one analog brought up is the MS Delta outbreak of 1971 that killed 122 people. That happened in a La nina, too.

This outbreak produced an F5, a lot has changed from then to now on how tornadoes are rated. Not saying we will get an EF5, but it looks like this system has a very real possibility of producing significant tornadoes

 

[andyhb]

The Euro is basically a non-event and a washout on Tuesday, which highlights the number one failure mode -> too much convection from Monday (and redeveloping due to the general lack of an inversion).