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Severe Weather 2021

Fred Gossage said:
Still questions in the modeling with how the Baja area upper low will affect the late week evolution. I think we may have these questions another day or so. I'm starting to get the vibe though that regardless of how Saturday evolves, we need to watch Friday into Friday night with the lead impulse that comes out. There won't be a lot of forcing, but shear will be there over the warm sector, and the thermos will be there... since the warm sector gets into place Thursday night into Friday morning.
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Fred, I noticed that too...should be be temporally limited due to lack of forcing ahead of it...maybe a couple of discrete cells.
 
Friday night into Saturday on the UKMET and a good half of the GEFS members is a situation similar to 11/10/02, 11/15/89, and 12/16/00.... where the main surface low is associated with the lead wave and moves way north of us Saturday morning, and is moving away, but as the trough approaches Saturday... height falls aloft and pressure falls along the front because of that make the wind fields respond like there is a surface low closer. There is also support for a secondary surface low along the front near Louisville or so around midday Saturday. Also, the fact that we aren't as sharply negatively tilted with the trough now may actually be more favorable for a discrete mode, with the large scale ascent a little more subtle and fanned out across the open warm sector, versus really strong forcing right ahead of the front. The Euro tonight will be really interesting. The Canadian is trying to head in this direction, but the evolution is a little faster. There is still very much a signal that Saturday has to be watched vigilantly from the Ohio Valley down to south MS/AL.
 
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Fred Gossage said:
Friday night into Saturday on the UKMET and a good half of the GEFS members is a situation similar to 11/10/02, 11/15/89, and 12/16/00.... where the main surface low is associated with the lead wave and moves way north of us Saturday morning, and is moving away, but as the trough approaches Saturday... height falls aloft and pressure falls along the front because of that make the wind fields respond like there is a surface low closer. There is also support for a secondary surface low along the front near Louisville or so around midday Saturday. Also, the fact that we aren't as sharply negatively tilted with the trough now may actually be more favorable for a discrete mode, with the large scale ascent a little more subtle and fanned out across the open warm sector, versus really strong forcing right ahead of the front. The Euro tonight will be really interesting. The Canadian is trying to head in this direction, but the evolution is a little faster. There is still very much a signal that Saturday has to be watched vigilantly from the Ohio Valley down to south MS/AL.
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I vividly remember each of those dates and that doesn't give me a great feeling about Saturday. Was just talking about 12/16/00 tonight actually, and how I thought Spann was going to throttle the person controlling the towercam.
 
MichelleH said:
I vividly remember each of those dates and that doesn't give me a great feeling about Saturday. Was just talking about 12/16/00 tonight actually, and how I thought Spann was going to throttle the person controlling the towercam.
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Poor Gary Kelley. That was actually their station general manager, and he was in covering because of folks off ahead of the holidays, and he was doing the best he could without knowing how to operate the camera. LOL

Right. And that situation, because of the things we previously talked about in here, would still have a warm sector with mid 70 temps, mid/upper 60 dewpoints, and currently face value modeled CAPE over 1200-1600 j/kg available. And despite the main surface low racing north, that low-level jet intensifies, and you still end up with face value modeled SRH of 300-400+. It's not a good idea. We just still need to watch to see how it evolves.
 
Euro is focusing heavier on the lead wave still, but it is a significant severe/tornado threat from the Ohio Valley down into north MS/AL Friday evening through Saturday early morning. This is in pretty heavy agreement with the operational GFS tonight.
 
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We're still going to get waffling back and forth for probably another day or so, but the 06z GFS threw its hat into the ring with the 00z UKMET and half of the 00z GEFS members, and has a slower evolution that still has a Friday night severe risk with the lead wave, but focuses on a slower moving second wave on Saturday that ejects out and gives a midday to evening severe risk, probably more organized, to MS/AL/TN/GA. We'll see how this continues to evolve...
 
Fred Gossage said:
Poor Gary Kelley. That was actually their station general manager, and he was in covering because of folks off ahead of the holidays, and he was doing the best he could without knowing how to operate the camera. LOL

Right. And that situation, because of the things we previously talked about in here, would still have a warm sector with mid 70 temps, mid/upper 60 dewpoints, and currently face value modeled CAPE over 1200-1600 j/kg available. And despite the main surface low racing north, that low-level jet intensifies, and you still end up with face value modeled SRH of 300-400+. It's not a good idea. We just still need to watch to see how it evolves.
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I've worked in local TV for 8 years, and it's always bothered me that my station doesn't have any skycams outside of our home city (where the station is). We have one on our tower, and one downtown. There's one town on the far western edge of our viewing area which has a webcam that we can take, and we can use the state DOT traffic cams, but we can't control any of those. Other than that, we're blind in the rest of our viewing area.
 
CheeselandSkies said:
I've worked in local TV for 8 years, and it's always bothered me that my station doesn't have any skycams outside of our home city (where the station is). We have one on our tower, and one downtown. There's one town on the far western edge of our viewing area which has a webcam that we can take, and we can use the state DOT traffic cams, but we can't control any of those. Other than that, we're blind in the rest of our viewing area.
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Are you guys WSI, Baron, or both?
 
akt1985 said:
A pretty healthy localized severe weather event is unfolding across the Tennessee Valley this morning.
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Report of shingles blown off a roof in St. Florian.

I was a little surprised to not see a severe watch this morning.
 
SPC seems a lot less interested in next weekend's system, citing positive tilt.
 

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Clancy said:
SPC seems a lot less interested in next weekend's system, citing positive tilt.
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And there are a lot of dead people in Alabama, Mississippi, Tennessee, and Georgia history over the years because of positive tilt systems.... including multiple F4-F5 days.
 
500mb trough/jet placement, orientation, etc., on the GFS/GEFS/UKMET solution is very similar to 11/10/2002, 11/27/1994, and 5/5/1999. It is moderately similar to 11/15/1989 and 12/16/2000... with the 850-sfc evolution with those two a closer match than the 500mb layout, which moderately matches what is modeled. There are some vague 500mb similarities, even, to 4/4/1977. Every single one of those days were positive tilt troughs with this type of orientation and evolution, and every single one of them were F3-F5 events in MS/AL/TN. That doesn't mean that this will, but the way this is modeled currently has several ugly synoptic matches... and all those synoptic analogs have the same thing in common that SPC is citing as a reason to downplay, and all of them were intense/deadly/violent tornado events.
 
Fred Gossage said:
And there are a lot of dead people in Alabama, Mississippi, Tennessee, and Georgia history over the years because of positive tilt systems.... including multiple F4-F5 days.
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Absolutely agree. I found it a little strange that they seemed slightly dismissive of the system because of the positive tilt.
 
Clancy said:
Absolutely agree. I found it a little strange that they seemed slightly dismissive of the system because of the positive tilt.
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Conventional wisdom from old school rules teaches that. You're taught that in courses in college. It takes real-world analysis of these actual events, especially the Dixie ones, to realize that the opposite can be true. Getting a significant discrete mode event with a positive tilt trough is really tricky, for the reasons that forecasters use the positive tilt to downplay a threat. However, when the positive tilt has height falls that overspread the warm sector, and the mid/upper flow fans out a bit overtop the warm sector, that type of setup has been associated with some really ugly Dixie events in the past. Even the 1974 Super Outbreak, which started negative tilt that morning, evolved into a positive tilt trough prior to any of the Alabama violent tornadoes. 4/8/98, 4/16/98, 5/18/95, and even 3/21/1932 if the reanalysis data is close to correct, were all positive tilt trough events. We have a long, deadly history with them, but they are tricky and it takes some specific circumstances with them.
 
2nd tornado warning of the morning, this one in southern Morgan County

 
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