Severe WX March 29-30, 2022 Severe Event

[DetectiveWX]

Good thing I got my whole house generator serviced, and there aren't big trees right next to my home.

 

[Equus]

Ah yes a day where the gradient winds are so strong the eventual intense QLCS actually feels like somewhat of a lull

 

[TileDude]

Good thing I got my whole house generator serviced, and there aren't big trees right next to my home.

I’m planning to fill up a couple of gas cans for my portable generator just in case.

 

[MattPetrulli]

00z HRRR looks pretty meh for discrete tornado potential, at least for most of MS/AL, really doesn't have much in the way of thermodynamics coming into MS/AL versus other models like GFS and NAM, it has most of the decent thermodynamics in LA during the day. That being said there's still a hint that the southern part is a little more broken (18-23z in LA/SW MS), so that's something of note. Biggest tor threat on 00z HRRR would be just in LA/SW MS, just not like a tornado outbreak or anything

 

[Educator]

School buses would be a nightmare.

Yes!
School system like where I run operations are going to need a time frame for the entrance into their areas of the high winds.
Buses are at risk with anything in the 40 mph range.

 

[Equus]

Day two moderate, for both wind and tornadoes

 

[MattPetrulli]

Day two moderate, for both wind and tornadoes

View attachment 12947

Seems they went for the 15% hatched off QLCS tornadoes. I don't recall seeing that before, maybe it's a reaction to the Mid-December derecho/tornado outbreak potentially. I thought there would be a small 10% hatched for tornadoes in LA/MS, didn't expect a 15. That being said a 15% hatched could honestly verify off QLCS tors given the crazy wind fields.

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF LOUISIANA...MISSISSIPPI...AND ALABAMA...

...SUMMARY...
A regional outbreak of severe thunderstorms is expected on Wednesday
across the Lower Mississippi Valley and Southeast States. All severe
hazards are possible, including significant gusts over 75 mph and
strong (EF2+) tornadoes.

...SEVERE-WEATHER OUTBREAK POSSIBLE ACROSS PORTIONS OF
LOUISIANA...MISSISSIPPI...AND ALABAMA...

...Synopsis...
A strong southern-stream shortwave trough is forecast to extend from
central KS through the TX Hill Country early Wednesday morning. This
shortwave is expected to progress eastward/northeastward throughout
the day, becoming increasingly negatively tilted as it does. Strong
mid-level flow will accompany this through, with 100+ kt at 500 mb
stretching from southeast TX northeastward through the Mid-South
Wednesday afternoon. Additionally, very strong low-level flow will
precede this feature, with a large area of 60+ kt at 850 mb expected
across the MS Valley Wednesday afternoon.

Low-level moisture advection will also precede this shortwave
trough, bringing at least low 60s dewpoints through the Mid-South/TN
Valley. Upper 50s dewpoints will likely reach into the Lower/Middle
OH Valley. These dewpoints will help foster at least modest buoyancy
and thunderstorms are anticipated as the shortwave ejects
northeastward over this moist and buoyant airmass. Given the
strength of the wind fields, severe thunderstorms are likely,
particularly across portions of the Lower MS Valley and Southeast
where a regional outbreak of severe thunderstorms is anticipated.

...Lower MS Valley into the TN Valley and Southeast...
A line of thunderstorms will likely be ongoing from the Ozark
Plateau southwestward into East TX early Wednesday. Expectation is
for this line of storms to quickly move eastward, outpacing a cold
front moving southeastward into the MS Valley. Widespread clouds
will limit diurnal heating downstream of this line of storms, but
strong moisture advection will still result in at least modest
buoyancy and airmass destabilization. At the same time, wind fields
will strengthen considerably. This combination of buoyancy and very
strong wind shear is forecast to result in a strengthening of the
line as it moves into eastern AR and LA during the early afternoon,
before then continuing quickly eastward across MS and AL during the
evening and overnight.

The kinematic fields, especially in the low-levels around 850 to 700
mb, are forecast to be very intense. Mean wind speeds from the HREF
show a corridor of 70 kt at 850 mb from central LA into southeast AR
at 18Z. Deep-layer mean winds are forecast to be 65+ kt across much
of LA, MS, and AL as the line moves through. Expectation is that
these robust wind fields will result in an intense convective line
capable of widespread wind damage. Embedded/QLCS tornadoes are also
likely within this environment, including the potential for strong
tornadoes (EF2+). Fast storm motion could result in longer-track
QLCS tornadoes than are typically observed.

In addition to the strong wind gusts and embedded QLCS tornadoes,
discrete supercells ahead of and/or south of the primary convective
line are also possible. Any discrete storm that is able to mature
and deepen would likely become an intense supercell capable of
producing severe wind gusts and strong tornadoes. However, the
forcing for ascent and fast-moving character of the shortwave (as
well as the convective line) do not favor a discrete convective
mode, and the current expectation is for the linear mode to
dominate.

..Mid MS and Lower/Mid OH Valleys...
Less low-level moisture and buoyancy is anticipated in the region
compared to farther south. However, strong forcing for ascent should
help maintain the convective line as it moves eastward through the
region. Strong wind fields support the potential for damaging wind
gusts with any deep convection, even in areas that exhibit shallow
low-level stability.

 

[Mr. Clark]

Welp.

 

[TileDude]

 

[Justin Hindman]

It's very rare , but I can't remember the last long track tornado in a QCLS. The wind fields are scary with this event, thank goodness the cape is low with this event. I expect a lot of wind reports, and a lot of whack a mole with tornadoes on the radar.

 

[mattdanielwx]

It's very rare , but I can't remember the last long track tornado in a QCLS. The wind fields are scary with this event, thank goodness the cape is low with this event. I expect a lot of wind reports, and a lot of whack a mole with tornadoes on the radar.

It's one reason why I'm a little confused with the tornado potential from SPC. We will definitely see QLCS spin-ups....but long track/strong? I feel like we need more instability for that.....and most of the unstable air will remain along the Gulf Coast tomorrow.

 

[CheeselandSkies]

Morning QLCS on 4/27/11 produced numerous strong tornadoes, some of them fairly long-track even by discrete supercell standards (20-30ish miles). As with everything about that day, even cutting it in half would be a pretty exceptional event.

Several strong tornadoes (up to EF3) have occurred with nighttime QLCS's here in the upper Midwest, most recently in the Chicago area last year.

 

[Justin Hindman]

Morning QLCS on 4/27/11 produced numerous strong tornadoes, some of them fairly long-track even by discrete supercell standards (20-30ish miles). As with everything about that day, even cutting it in half would be a pretty exceptional event.

Several strong tornadoes (up to EF3) have occurred with nighttime QLCS's here in the upper Midwest, most recently in the Chicago area last year.

Correct, I do remember that, but this isn't April 27, that's a 1/40 year event. I remember that also taking us by surprise. I know they can happen for sure,, but I'm just not sold on that happening. We could see 200 plus wind reports though.

 

[Fred Gossage]

Correct, I do remember that, but this isn't April 27, that's a 1/40 year event. I remember that also taking us by surprise. I know they can happen for sure,, but I'm just not sold on that happening. We could see 200 plus wind reports though.

The 40 year return rate comments about 4/27 have always been strictly about the afternoon violent tornado outbreak, not about the morning QLCS. That was a serial derecho with embedded strong tornadoes, and even though that doesn't happen too often, it has been seen several times before. I just don't think the ingredients for that level of strong tornado QLCS threat will be with us. It would take likely 1500+ CAPE as the average in the instability axis, just based on the environmental profile that early morning, and we don't quite have that for this. But I do think a couple of tornadoes in the QLCS may be EF2 or maybe up to lower EF3 (we see that a good bit more often than a lot of people like to admit), and because of the fast storm motions, tornadoes of any intensity in the line may be a slight touch longer-tracked than they otherwise would be. But even if there are a couple of strong tornadoes in the line, the big deal tomorrow is going to be the widespread 70-80 mph wind swath with what will probably be a serial derecho.

 

[Justin Hindman Hindy]

The 40 year return rate comments about 4/27 have always been strictly about the afternoon violent tornado outbreak, not about the morning QLCS. That was a serial derecho with embedded strong tornadoes, and even though that doesn't happen too often, it has been seen several times before. I just don't think the ingredients for that level of strong tornado QLCS threat will be with us. It would take likely 1500+ CAPE as the average in the instability axis, just based on the environmental profile that early morning, and we don't quite have that for this. But I do think a couple of tornadoes in the QLCS may be EF2 or maybe up to lower EF3 (we see that a good bit more often than a lot of people like to admit), and because of the fast storm motions, tornadoes of any intensity in the line may be a slight touch longer-tracked than they otherwise would be. But even if there are a couple of strong tornadoes in the line, the big deal tomorrow is going to be the widespread 70-80 mph wind swath with what will probably be a serial derecho.

Problem is the short ones can happen between radar scans and by the time you warn for theme, they are already gone unless you get 1 or 2 that stay down for 10 minutes plus. It will be interesting to see how the nws warns tomorrow. I know Jackson will issue at least 15 tornado warnings

 

[WhirlingWx]

Another thing to keep in mind, similar to 12/15/21 -- obviously not suggesting that we see a similar number of tornadoes, just the (relative) ease at which a tornado could reach sig intensity

 

[David in SW Blount]

The 40 year return rate comments about 4/27 have always been strictly about the afternoon violent tornado outbreak, not about the morning QLCS. That was a serial derecho with embedded strong tornadoes, and even though that doesn't happen too often, it has been seen several times before. I just don't think the ingredients for that level of strong tornado QLCS threat will be with us. It would take likely 1500+ CAPE as the average in the instability axis, just based on the environmental profile that early morning, and we don't quite have that for this. But I do think a couple of tornadoes in the QLCS may be EF2 or maybe up to lower EF3 (we see that a good bit more often than a lot of people like to admit), and because of the fast storm motions, tornadoes of any intensity in the line may be a slight touch longer-tracked than they otherwise would be. But even if there are a couple of strong tornadoes in the line, the big deal tomorrow is going to be the widespread 70-80 mph wind swath with what will probably be a serial derecho.

I'm not a fan of the "generational outbreak" terminology anyway. I get why it's used to convey the rarity of days like 4/27/11, but it also implies that we won't see another day like that until around 2051. That's not how probability works, as we know.

 

[Fred Gossage]

I'm not a fan of the "generational outbreak" terminology anyway. I get why it's used to convey the rarity of days like 4/27/11, but it also implies that we won't see another day like that until around 2051. That's not how probability works, as we know.

Me neither. I'm of the opinion that another event like that will happen when the atmosphere supports it, whether it is next month or it waits until 300 years from now.

 

[keithGA]

1730z update from SPC.

 

[brianc33710]

The 40 year return rate comments about 4/27 have always been strictly about the afternoon violent tornado outbreak, not about the morning QLCS. That was a serial derecho with embedded strong tornadoes, and even though that doesn't happen too often, it has been seen several times before. I just don't think the ingredients for that level of strong tornado QLCS threat will be with us. It would take likely 1500+ CAPE as the average in the instability axis, just based on the environmental profile that early morning, and we don't quite have that for this. But I do think a couple of tornadoes in the QLCS may be EF2 or maybe up to lower EF3 (we see that a good bit more often than a lot of people like to admit), and because of the fast storm motions, tornadoes of any intensity in the line may be a slight touch longer-tracked than they otherwise would be. But even if there are a couple of strong tornadoes in the line, the big deal tomorrow is going to be the widespread 70-80 mph wind swath with what will probably be a serial derecho.

Correct! The am outbreak was bad enough but not the "generational" event that pm. Birmingham has "lucked" out over the last year with severe weather threats reduced by flooding rains. I use the quotes cause the floods have caused death & destruction on their own. Didn't Easter 2020 also feature EF2-3s in the QLCS line?