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Severe 3/17/21 Severe Weather Outbreak Al/Ms/Tn/Ar nowcast

Arcc said:
Well had we had 0-1km helicity across AL around 300 today, it verifies the High easy. However that can be said for a handful of events over the past years as well. Also it’s not like the helicity here busted low, it was fairly well models.
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fully agree. And honestly we did see some strong tornado signatures today even through all this. Goes to show how much worse this could have been. I’m no severe expert at all but seems like our lack of helicity can be blamed. Today was not a day where every single cell spun up instantly. I’ve seen cells form and have tornadoes on the ground in 15-20min. I believe the mid April 2011 NC outbreak had a cell go tor warned 10-15min After forming. Today seemed much harder for tornadoes to form.

The bust conversation always comes up and I’m just as guilty as the next. But really hindsight is 20/20. This morning there certainly was a legit argument for high risk although maybe not the most prolific event. Personally I think high risk (or the top tier threat level) should be reserved for the most prolific outbreaks to preserve a level of respect that this event is going to be something beyond normal. An extreme event. Under that opinion today probably wouldn’t fall into that category. But I’m not the one in charge so who cares what I think :D
 
Myfrotho704_ said:
I still can’t get over the Easter Sunday setup, shear was there but it was so messy, imo that setup had a shot to be close to 2011 vs this one
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The closest thing in my mind to 4/27/11 was the day of the Beauregard tornado. Now that event still would have fell well short, but add a stronger EML and move the system north 200 miles. Oh my.
 
Another thing to is that typically dewpoints/temps are lower in March vs April at this time on average which matters quite a bit in severe wx setups, that’s probably a flaw to comparing March setups with April setups, for ex in March you could be getting 73/65 vs 78/68 in April
 
Arcc said:
The closest thing in my mind to 4/27/11 was the day of the Beauregard tornado. Now that event still would have fell well short, but add a stronger EML and move the system north 200 miles. Oh my.
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That setup was disgusting, it had more potential to be more nasty then it was
 
Wouldn’t be surprised if there wasn’t a spin up in that short lived meso near Kellyton. A little close for comfort.
 
I feel for the folks at NWS that are responsible for issuing the outlooks and trying to decide what threat level this or any event is. It's really a no win situation for them....Had they went more conservative with their guidance and we had a more severe outbreak we would be criticizing them for not doing enough....same thing goes the other way....a lot of people are now saying how they shouldn't have been so bullish in their approach to today's system. Damned if you do and damned if you don't :)
 
Didn’t hear any thunder here, and going to have less than an inch of rain for the past three days.
 
Coolest part of the storm so far. The wind is sooooooo loud outside but it's not all transporting down. Occasional gust hits, but it's a continuous roar and then louder at times even though the line has already gone through. It woke the kids up! Just eerie hearing it so loud higher up but not ground level.
 
My hugest wind gust as the line of dying storms went through my area, 4.5 mph. Lol! Not quite the 75 mph forecast. The wedge is king, once again!
 
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bnathanb1982 said:
I feel for the folks at NWS that are responsible for issuing the outlooks and trying to decide what threat level this or any event is. It's really a no win situation for them....Had they went more conservative with their guidance and we had a more severe outbreak we would be criticizing them for not doing enough....same thing goes the other way....a lot of people are now saying how they shouldn't have been so bullish in their approach to today's system. Damned if you do and damned if you don't :)
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The only criticism that should be given is for keeping the high risk in last nights update.
 
Arcc said:
My thoughts:

1: Round one failed because of meager low level helicity. I’ve seen it many times and this is what happens when 0-1km helicity is 150-200. You have storms spin like a top, with little ground truth unless the storm rides a boundary or it strengthens enough to finally get a tornado down for a short period of time. This was pretty well modeled.

2. I believe round two failed because of unidirectional flow aloft. This lead to messy storm modes which also helped work over the area. Most of the modeled helicity was speed shear not directional shear(the opposite happened over AL)This was also well modeled.

3. Initiation of supercells the occurred earlier and speed of the squall line also helped. The past few days had supercell initiation over central AL at or around 21z to 0z, however supercells were being initiated by 11am this morning. Slow them down and the shear increases some, although I don’t know if it changes the event.

4. The CAMs were throwing out warning after warning with the overall lack of UH streaks over the high risk area. These are never fully accurate and bust often, but when models that absolutely love to nuke the area don’t nuke the area, they may be on to something.
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Bravo!!! That’s what I was thinking after about 730 last night when things were weakening... I don’t know what all the numbers translate to, but I am learning what they mean! Great explanation!?
 
Sleet City USA said:
It may have busted in the high risk zone, but man it did not for these folks. This has got to be 4+ right?
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The Chilton county is preliminary strong EF2 last I read. That was probably a doublewide trailer. The only time I chased tornado damage was the next day following 4/15/11 when my wife and I drove to Prattville. The tornado hit a double wide and it was just gone with nothing but the steps left. Unfortunately the person inside was killed. It was rated EF3. Mobile homes provide absolutely no protection in strong tornadoes.
 
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