March 17-18 Severe Weather Event

[nwohweather]

Gonna be interesting here folks. So much shear and helicity in the air, once we get this crapvection out of here that line is for sure going to spark of some storms all across SC/NC

[LKN WX]

That wedge boundary in CLT is pretty amazing-was 75 at Carowinds Blvd while it’s 58 at my house in Denver.  It dropped like a rock once I headed up 16 off of 485.

[brianc33710]

6 hours ago, eyewall said:

Yep. 50F and drizzle isn't going to get the job done.

Christmas 2012 in AL was another battle between the storms & a warm front. North of the front featured severe thunderstorms. But in the warm sector closer to the coast tornadoes developed & did move extensive damage.

I will say this though. The stars almost aligned yesterday to give us an event probably somewhere between Easter 2020 & 27 April 2011. The spring is still young & the Gulf has more to warm before the Dixie Alley outbreak risks subside.

I have a feeling we will have something like what was possible yesterday in the next couple of months. I of course could be wrong but my gut tells me to remain prepared. 

[NorthHillsWx]

Storm moving towards jonesville might need a tornado warning 

[Kristospherein]

74 here in South Charlotte with a 68 dew point and both are starting to drop after highs at 310 and 210, respectively. I think the tornado threat is greater further south based upon what I've read and seen but who knows with a line like the one coming. 

[Avdave]

Temps have gone up currently 70/66 with a few peeks of sunshine here near RDU

[Avdave]

[NorthHillsWx]

I’m thinking this busts pretty significantly even for a level 3 severe weather outlook. That line looks to ride the wedge boundary I could see a few severe cell segments in the line but i don’t think there will be enough instability this afternoon further east to induce many showers or storms. There may even be some areas from the triangle to the coast that avoid all rain period until the ULL swings through tonight. Definitely looking like a run of the mill system in terms of severe potential here. We’re at the point, 4 pm, where we’d be seeing cell development outside that line and it’s just too stable. Certainly looking at a very isolated severe event 

[NorthHillsWx]

I say bust too being they dismissed schools early and many business across the eastern part of the state closed between 2-4 in anticipation of severe weather. Many of these areas may not see any weather (rain) period. That’s a bust when you get to the point of closing schools and businesses and there isn’t a severe report within 100 miles when you started the day in a level 3-4 severe threat.

[nwohweather]

5 minutes ago, NorthHillsWx said:

I’m thinking this busts pretty significantly even for a level 3 severe weather outlook. That line looks to ride the wedge boundary I could see a few severe cell segments in the line but i don’t think there will be enough instability this afternoon further east to induce many showers or storms. There may even be some areas from the triangle to the coast that avoid all rain period until the ULL swings through tonight. Definitely looking like a run of the mill system in terms of severe potential here. We’re at the point, 4 pm, where we’d be seeing cell development outside that line and it’s just too stable. Certainly looking at a very isolated severe event 

Terrible take in my opinion. Massive clearing is unfolding across GA/SC/NC with CAPE surging. We have 60-70 knots of bulk shear, SRH at 200-400 to boot. It would not shock me at all if the atmosphere recovers fully to get 1-2 long track tornadoes this evening

[eyewall]

2 minutes ago, NorthHillsWx said:

I say bust too being they dismissed schools early and many business across the eastern part of the state closed between 2-4 in anticipation of severe weather. Many of these areas may not see any weather (rain) period. That’s a bust when you get to the point of closing schools and businesses and there isn’t a severe report within 100 miles when you started the day in a level 3-4 severe threat.

I will take a consolation shelf with the QLCS

[NorthHillsWx]

6 minutes ago, eyewall said:

I will take a consolation shelf with the QLCS

May have to get your spotlight out. I’m not sure it gets here before dark. 

[eyewall]

Just now, NorthHillsWx said:

May have to get your spotlight out. I’m not sure it gets here before dark. 

yeah I may roll west a bit.

[Drummer]

I'm in York, looks like I'm about to get the part that was previously tor warned.  Can't really leave the room since I'm self quaranting (covid positive, but mild case).  Day started off pretty cool, cloudy, foggy, but I noticed the sun peeking through early afternoon before these clouds rolled in.  Temps have been mid/high 60s since, dewpoints in the 60s as well.  Getting a little breezy.  Not as worried as I was late last night but a little more worried than I was when I woke up.  Hopefully it won't be much, but we'll see what she's got.  Will be interested in seeing what comes after it crosses through the CLT metro.

[Avdave]

73 with a dew of 67 now. Sun is more than not

[DanLarsen34]

2 hours ago, Hoosier said:

Just to comment on yesterday for a minute... I would not call it a bust.  IMO, that word is thrown around way too often in severe weather events.  Perhaps it fell a bit short of the potential that it had, though.  

I can't find reference to it anymore, but SPC used to issue a high risk when they were expecting at least 20 tornadoes in a geographical area that is the size of Oklahoma without the panhandle.  I believe there was also some threshold for the number of F/EF2 tornadoes but can't recall for sure.  Very important to remember that not every high risk is going to produce 100 tornadoes or even 50 tornadoes.  There are those days that are elite level... I would almost call those extreme risk days.

I think this is a great summary of yesterday.

I'm guessing by the time that all damage surveys are completed that we had something approaching high risk verification (30% or higher within 25 miles) across central Alabama. However, most of the tornado activity occurred just on the edge or just outside of the 30% contour. Virtually the entire high risk area west of Alabama busted yesterday (literally wasn't a tornado report indicated in the high risk area of MS for example). The only part of the 45% contour that even saw tornado reports was the eastern tip surrounding Tuscaloosa. 

Yesterday was a middling performance for a high risk today. Looking at this 2017 article that was published on the day of January 21st High Risk, when you look at how all high risk areas performed between 2010 and 2014 (last one issued until 1-21-2017), a little over half of those days saw at least one violent tornado. All but two saw at least several significant tornadoes too. We didn't have anything violent yesterday, but I'm guessing at least a handful of tornadoes may have reached strong intensity (EF2+).  https://www.ustornadoes.com/2017/01/22/heres-last-15-high-risks-tornadoes/

Part of the reason why it feels like high risks have been busting lately is because we haven't had a high risk day since April 28, 2014 that's produced a significant number of tornadoes AND produced violent tornadoes. The SPC had a hell of run with their high risks from April 27, 2011 to April 28, 2014 partly because we saw some really high-end outbreaks. I think that may have distorted our expectations a bit as to what high risk days usually do. 

That said, they have had a great deal of bad luck with the high risks that they have issued since that April 28, 2014 outbreak. Some have, I think, quite rightfully questioned their decisions on some days that probably shouldn't have gone high. 2017 had a number of busts in this regard (the April GA one being the most obvious). Few questioned the decision to go High on May 20, 2019, though, and I think few would blame them for issuing that forecast even in hindsight. One or two subtle things being off that day might have saved us from a historic outbreak. A similar thing occurred on January 21, 2017. It's easy to second guess decisions with the benefit of hindsight, but not all high risk days were considered mistakes at the time that they were issued. This dynamic played out the other way with the major outbreak we saw on April 12 last year (community seemed split on issuing a high risk, most thought they were right not to after only two discrete cells did anything, then the QLCS threat more than verified a high risk).

I also think this discussion tends to look past one key element too: that the SPC outlooks are probability based. When we talk about what FEELS like a high risk day (multiple discrete cells producing long-tracking, violent tornadoes) this is different than what the SPC's criteria are. It's crucial to remember this.

One last thing I would add is that days like yesterday are a good reminder that, for as much the science of meteorology has advanced, there is still much left that still need to learn. That's why I love the work that many of you do in this field as outside observer. 

 

 

[nwohweather]

Nice little CU field back in GA here, sun is now out here as well

[NorthHillsWx]

35 minutes ago, nwohweather said:

Terrible take in my opinion. Massive clearing is unfolding across GA/SC/NC with CAPE surging. We have 60-70 knots of bulk shear, SRH at 200-400 to boot. It would not shock me at all if the atmosphere recovers fully to get 1-2 long track tornadoes this evening

I’m failing to see the mode for storm formation outside the current line. There seems to be massive subsidence between the QLCS moving through the western Piedmont and the convention hugging the coast. Yes, there are positive tornado parameters present and some would favor a significant tornado, but by the time that line gets  east to where the CAPE has surged it will be well after nightfall. The front remains west and the biggest forcing is along the wedge front. I do believe there will be severe weather, but I think it’s going to be limited to roughly Columbia-Raleigh and relatively nothing east of there. It will not be widespread either. I do think there could be a tornado or two, I’m absolutely not saying we’re out of the woods, but it will not be a widespread severe day 

[Drummer]

29 minutes ago, Drummer said:

I'm in York, looks like I'm about to get the part that was previously tor warned.  Can't really leave the room since I'm self quaranting (covid positive, but mild case).  Day started off pretty cool, cloudy, foggy, but I noticed the sun peeking through early afternoon before these clouds rolled in.  Temps have been mid/high 60s since, dewpoints in the 60s as well.  Getting a little breezy.  Not as worried as I was late last night but a little more worried than I was when I woke up.  Hopefully it won't be much, but we'll see what she's got.  Will be interested in seeing what comes after it crosses through the CLT metro.

Not too bad, came and went pretty quickly.  Our house overlooks Nanny Mountain (more of a glorified hill if you ask me), but it was pretty cool seeing it get engulfed in the rain.  Oddly no wind here, especially odd considering the tor warning just popped when it was maybe 1-2mi east of us. Just heavy rain and pea-sized hail.

[kvegas-wx]

Tornado warning eastern triad.

Rotating cell headed into Thomasville area and then out to I85 east of GSO.  

[magpiemaniac]

Tornado warning issued for Davidson, Forsyth, and Guilford.  All you dorks who predicted a bust can go suck an egg.  It’s completely different when it’s your own life and property.

[nwohweather]

Nice updraft on the cell just west of Charlotte. If that thing tightens up could see a potential tornado in a heavily populated area

[Kristospherein]

Tornado warning South meck near tega cay area. Heading my way 5PM eta. 

 

[HKY_WX]

That a nasty cellheading towards south Charlotte 

[Avdave]

[Drummer]

Sirens going off in the Lake Wylie/Steele Creek area.  Not sure if it's from Catawba Nuclear or if those towns have their own.

[mob1]

3 minutes ago, HKY_WX said:

That a nasty cellheading towards south Charlotte 

Rotation is definitely tightening on that as it passes Pineville. 

[HKY_WX]

Suns out and 73 here in Raleigh.  Btw

[NorthHillsWx]

The pineville storm is likely to be the storm of the day. Has a ripe environment in front of it too

[nwohweather]

Charlotte cell moving into better instability and SRH as it goes east. To be honest it may drop in the city as I'm getting 80 mph winds already per RadarScope in the couplet