April 12 Severe Event

[crossbowftw3]

11 minutes ago, StormySquares said:

4/7/06 was also the only 60 sig tornado risk. I wonder if we would see that ever again. 

Not personally sure myself. From my research of that event they only did 60% sig because they were certain a major outbreak would happen. A big outbreak did happen, but fell quite short of verifying. They did want to do day 2 high for 4/27 but questions about the morning wave prevented that. As we know now, that morning wave (really both) didn't. 

 

4/27 probably would have verified 60% with room to spare in all honesty.

[PackGrad05]

Speaking for NC, it would be a low instability until the wee morning hours on Monday.  Sunday looks to be wedged in with CAD most of the day...  if that eroded a little quicker, we could destabilize more.   Main threat for NC (as of now) is straight-line winds as the front moves through.

[nwohweather]

With our family postponing Easter in Savannah and no church services I think I'm going to head out from Charleston to chase this one. Mid-level jet will be roaring around 100 kts, solid destabilization, and large curved hodographs all look like a great setup. Also it is important to note that the better setup is on the Euro which bodes well if you're looking for tornadoes.

 

[StormySquares]

Wow 0z Nam is rough. More bullish on the EML and even *more* MLCAPE. Also keeps the large expansion of the risk area. Might be a HOF model run

[Bob's Burgers]

Tennessee is very much in the mix now. NAM gets more and more dangerous per run. 

[Bob's Burgers]

Notice the 73 knot storm motion for right movers; northern MS sounding here, maybe 70 miles west north west of Tupelo 

[ingyball]

I don't post here often, mostly lurk, but wanted to post the 21z SREF Sigtor probs for 21z on Sunday. 

[jojo762]

5 minutes ago, ingyball said:

I don't post here often, mostly lurk, but wanted to post the 21z SREF Sigtor probs for 21z on Sunday. 

SigTor of 90 at hour 72 is extraordinarily rare... wow. 

[bdgwx]

You guys beat me to it. I was just going to post the SREF tornado ingredients product myself. A 90 contour at F72 is rare indeed.

[nwohweather]

Notice the 73 knot storm motion for right movers; northern MS sounding here, maybe 70 miles west north west of Tupelo 

LI’s of -9 and SRH at the lowest levels of 450. Good heavens. Also LCL’s are really low there, you could get some groundscraping wedges out there

[Indystorm]

And excellent low level moisture.  The 3/28 moderate risk over western IL busted because the moisture did not reach as far north as expected.  Unfortunately Dixie is much closer to the Gulf.

[jojo762]

Models have pretty much converged on a scary scenario for a large area... Encompassing perhaps parts or most of: Louisiana, Arkansas, Mississippi, Tennessee, Alabama, and perhaps Georgia.

00Z NAM, et. al, indicate that by as early as 18z on Sunday, the warm front will have lifted to the Tennessee border with a rather expansive, moist warm sector to its south.

NAM is a tad more aggressive with instability than other models at this moment, but all models pretty much show a significant parameter space across a large area from 15z to 03Z (and beyond) on Sunday. General trend has been for less warm sector precip, as well... which is concerning. 

 

[Radtechwxman]

5 hours ago, StormySquares said:

4/7/06 was also the only 60 sig tornado risk. I wonder if we would see that ever again. 

If any day was ever worthy of it, it was 4-27-11. Such a high concentration of strong to violent tornadoes 

[SluggerWx]

Huge Day 3 MOD posted by SPC

 

https://www.spc.noaa.gov/products/outlook/day3otlk.html

 

https://www.spc.noaa.gov/products/outlook/day3otlk_0730.gif

 

Sent from my Pixel XL using Tapatalk

 

 

 

 

 

 

 

 

 

 

[cheese007]

45% hatched area on D3 is wild!

[shaggy]

Looks ominous for the deep south again. A little less concerned here in the coastal plains due to timing. Hope people are paying attention.

[DanLarsen34]

That’s the largest day 3 moderate risk I’ve ever seen. 

[eyewall]

They are definitely setting the stage to go to high risk tomorrow or on Sunday. Either way if this doesn't bust, this could be a memorable event.

[joshwx2003]

2 minutes ago, eyewall said:

They are definitely setting the stage to go to high risk tomorrow or on Sunday. Either way if this doesn't bust, this could be a memorable event.

Try Historical.I have a feeling that this will be the worst tornado outbreak in history for the US.The models show no convection in the morning and just insane parameters which will setup a worst case scenario.

[jpeters3]

10 minutes ago, joshwx2003 said:

Try Historical.I have a feeling that this will be the worst tornado outbreak in history for the US.The models show no convection in the morning and just insane parameters which will setup a worst case scenario.

Please don't post things like this.  While some of the projected environmental parameters look impressive, they already don't look as impressive (less CAPE) as events like 4-27-11.  And 4-27-11 didn't even quite reach the scope of the super outbreak in 74.  I don't think there is any indication that this will exceed the spatial coverage or intensity (number of EF-4+ tornadoes) as either of those outbreaks.

And if there is anything the last few years have taught us, there are plenty of ways for a potent looking event 2 days out to end up busting.

[Quincy]

Want to try to not get too specific on details this far out, but the synoptic signal is there for a potentially higher-end event. There are some key differences, but 4/27/11 is ranking as a relatively close analog at this stage. 

Speaking of details/trends, the GFS/Euro have been trending a bit slower and to the west. That’ll be something to keep an eye on, which may put AR/LA more into the action, as opposed to AL and areas farther east. If the system slows a bit and remains more neutrally tilted as opposed to negatively tilted, that’s setting off more alarm bells.

The shortwave is looking somewhat more progressive and compact than some historical major events. 4/27/11 and 4/28/14, for example, were more amplified with upper level lows cutting off. If the progs are correct, a northwesterly 100kt 500mb jet will spell trouble.

Remember your MS vicinity climo. Mean MLCAPE for tornadoes is only ~500 to 1000 J/kg and 1000 to 2000 for significant tornadoes. Global models and longer range NAM get you into the latter camp. Wind profiles speak for themselves, very impressive at face value. 

Global models showing a string-of-pearls QPF signal ahead of the cold front is alarming, especially if there is a pre-frontal trough. I try to not look at forecast soundings too much, but a warm nose/cap around 850-750mb during the first half of the day would suppress precipitation and with cooler temperatures aloft penetrating, that’s why you’re seeing seasonably large instability profiles. 

Summary: Don’t get hung up on details. The synoptic signal is alarming. Watch for a slower/westward trend. 

[StormySquares]

2 minutes ago, Quincy said:

Want to try to not get too specific on details this far out, but the synoptic signal is there for a potentially higher-end event. There are some key differences, but 4/27/11 is ranking as a relatively close analog at this stage. 

Speaking of details/trends, the GFS/Euro have been trending a bit slower and to the west. That’ll be something to keep an eye on, which may put AR/LA more into the action, as opposed to AL and areas farther east. If the system slows a bit and remains more neutrally tilted as opposed to negatively tilted, that’s setting off more alarm bells.

The shortwave is looking somewhat more progressive and compact than some historical major events. 4/27/11 and 4/28/14, for example, were more amplified with upper level lows cutting off. If the progs are correct, a northwesterly 100kt 500mb jet will spell trouble.

Remember your MS vicinity climo. Mean MLCAPE for tornadoes is only ~500 to 1000 J/kg and 1000 to 2000 for significant tornadoes. Global models and longer range NAM get you into the latter camp. Wind profiles speak for themselves, very impressive at face value. 

Global models showing a string-of-pearls QPF signal ahead of the cold front is alarming, especially if there is a pre-frontal trough. I try to not look at forecast soundings too much, but a warm nose/cap around 850-750mb during the first half of the day would suppress precipitation and with cooler temperatures aloft penetrating, that’s why you’re seeing seasonably large instability profiles. 

Summary: Don’t get hung up on details. The synoptic signal is alarming. Watch for a slower/westward trend. 

To be clear, a slower/westward trend would be more or less severe?

[DanLarsen34]

Just now, jpeters3 said:

Please don't post things like this.  While some of the projected environmental parameters look impressive, they already don't look as impressive (less CAPE) as events like 4-27-11.  And 4-27-11 didn't even quite reach the scope of the super outbreak in 74.  I don't think there is any indication that this will exceed the spatial coverage or intensity (number of EF-4+ tornadoes) as either of those outbreaks.

And if there is anything the last few years have taught us, there are plenty of ways for a potent looking event 2 days out to end up busting.

On this note: the outflow boundaries laid out by morning convection on 4-27 actually ENHANCED the tornado risk across NE MS, and NW AL. Subtle thing like this won’t be evident until hours before storm initiation is set to occur. Those small details are what can make the difference between a significant outbreak and something “historic.” 
 

4-3 and 4-27 have set the bar EXTREMELY high for any subsequent outbreak to exceed. Even something a magnitude below that (let’s say 60-90 tornadoes, 5-8 violent tornadoes) would be devastating. This certainly has a very high ceiling, but everything has to break right for a 4-27 or 4-3 to occur. We won’t know that until the day one of those events is about to occur again, even if the larger scale suggests it’s possible. 

[DanLarsen34]

Some good advice here from Tony Lyza. 

 

[Quincy]

1 minute ago, StormySquares said:

To be clear, a slower/westward trend would be more or less severe?

I think it’s more about placement. To be clear, I’m not seeing any significant trends with respect to speed and orientation of trough amplification. It’s more about a gradual westward tick.

Hopefully that makes sense. I’m trying to make sure I don’t get too hung up on specifics either.

[METALSTORM]

Maybe throwing around comparisons to 4/27/11 isn't a very good idea at this point. Every parameter was so off the scale that day it almost wasn't believable. Birmingham broke 90 that day providing the tornadic equivalent of 110 octane racing fuel. This upcoming event certainly looks very ominous and looks like a significant threat to life and property but maybe comparisons to past events should wait until the event has moved on. Just my 2 cents. I'll see myself out now.

[Santa Clause]

34 minutes ago, Quincy said:

Want to try to not get too specific on details this far out, but the synoptic signal is there for a potentially higher-end event. There are some key differences, but 4/27/11 is ranking as a relatively close analog at this stage. 

Speaking of details/trends, the GFS/Euro have been trending a bit slower and to the west. That’ll be something to keep an eye on, which may put AR/LA more into the action, as opposed to AL and areas farther east. If the system slows a bit and remains more neutrally tilted as opposed to negatively tilted, that’s setting off more alarm bells.

The shortwave is looking somewhat more progressive and compact than some historical major events. 4/27/11 and 4/28/14, for example, were more amplified with upper level lows cutting off. If the progs are correct, a northwesterly 100kt 500mb jet will spell trouble.

Remember your MS vicinity climo. Mean MLCAPE for tornadoes is only ~500 to 1000 J/kg and 1000 to 2000 for significant tornadoes. Global models and longer range NAM get you into the latter camp. Wind profiles speak for themselves, very impressive at face value. 

Global models showing a string-of-pearls QPF signal ahead of the cold front is alarming, especially if there is a pre-frontal trough. I try to not look at forecast soundings too much, but a warm nose/cap around 850-750mb during the first half of the day would suppress precipitation and with cooler temperatures aloft penetrating, that’s why you’re seeing seasonably large instability profiles. 

Summary: Don’t get hung up on details. The synoptic signal is alarming. Watch for a slower/westward trend. 

Great post! Keep them coming man.

[Quincy]

CIPS analogs show a relatively high correlation with tornadic events based on the 00z GFS. 4/27/11 is #2 and yes, some other analogs are much more tame. 

Percent of analogs with at least one long-track tornado:

[StormySquares]

It's probably fair to say it looks similar to 4/27/11 synoptically but that certainly doesn't equal the same outcome. 

[nwohweather]

Maybe throwing around comparisons to 4/27/11 isn't a very good idea at this point. Every parameter was so off the scale that day it almost wasn't believable. Birmingham broke 90 that day providing the tornadic equivalent of 110 octane racing fuel. This upcoming event certainly looks very ominous and looks like a significant threat to life and property but maybe comparisons to past events should wait until the event has moved on. Just my 2 cents. I'll see myself out now.

Bingo. This setup for Easter is incredible, one of the best I’ve ever seen. But April 27th was Michael Jordan, hands down the greatest setup of all-time. And it led to some of the most memorable tornadoes ever as well.

However here is an actual quote from the SPC Outlook on that morning...

“THE WIND SHEAR ENVIRONMENT WILL ALSO RAPIDLY BECOME MORE
FAVORABLE AS THE NOSE OF A 80 TO 100 KT MID-LEVEL JET EJECTS EWD
ACROSS THE REGION AND INTERACTS WITH A WELL-DEVELOPED LOW-LEVEL JET.
THIS WILL CREATE LARGE LOOPING HODOGRAPHS FROM ERN MS AND NCNTRL AL
NWD INTO SRN TN. 0-3 KM STORM RELATIVE HELICITIES IN THE 450 TO 600
M2/S2 RANGE SHOULD BE VERY FAVORABLE FOR TORNADIC SUPERCELLS”

It’s very similar in setting the stage, just with a tad less instability. Storm motions will be insane on Sunday, 65-75 mph