• Welcome to TalkWeather!
    We see you lurking around TalkWeather! Take the extra step and join us today to view attachments, see less ads and maybe even join the discussion.
    CLICK TO JOIN TALKWEATHER

Severe Weather 2025

Pattern for next week appears to be unraveling with the trough not phasing properly and one of the shortwaves feeling the weakness from the TC in the eastern Pacific. Leads to much less flow over the Plains.
 
12z GFS says "just kidding" and brings the flow right back lol. Ryan Hall seems to think any disturbance in the jet streak means bad news this time of year with the moisture and CAPE already in place. Which is probably a solid take mixed with a little hype casting.

The cold front does look like it'll be decently powerful and provide a good bit of forcing. That jet streak is the biggest question mark currently. Lots of tricky interactions happening by the looks of it.
 
Grand Poo Bah said:
Went through my collection of soundings and found some June low-sheer tornadic events. Low sheer June tornadoes are pretty common in Montana, Wyoming, Colorado, and the Dakotas.

Barnard, SD EF4
View attachment 43448

A photogenic F3 with 5 other tornadoes in Kansas. 06/13/2004.
View attachment 43414

An EF4 tornado and the largest outbreak on record for Minnesota. 2010 had 5 June tornadic events.

View attachment 43440

Massachusetts long-lived EF3 in 2011

View attachment 43441

"cold-core" outbreak in the Northern Plains. 2011

View attachment 43442

The Pilger, NE twins. 2014.

View attachment 43443

Photogenic South Dakota EF4. 2014

View attachment 43444

A simultaneous cyclonic and anticyclonic tornado in Colorado. 2015.

View attachment 43445

Higher sheer, but the most notable June tornado of the last few years.

View attachment 43446

Kansas tornadoes and mothership supercells
View attachment 43447

Additionally, there haven't hardly been any June outbreaks in the plains in the last 10 years, and most of the meanest June tornadoes in the plains occur with 60-80 kt eff sheer. When sheer gets that high, June tornadoes get especially violent. With several large outbreaks and EF4s.
Click to expand...
Do you mean effective shear values? Because I would definitely not call anything above 200 m2/s2 of 0-3 km SRH low shear (I see some >400 m2/s2 soundings in here too?) Maybe for violent tornadoes 200 m2/s2 is a little low, but that's still adequate for tornadogenesis.
 
slenker said:
Do you mean effective shear values? Because I would definitely not call anything above 200 m2/s2 of 0-3 km SRH low shear (I see some >400 m2/s2 soundings in here too?) Maybe for violent tornadoes 200 m2/s2 is a little low, but that's still adequate for tornadogenesis.
Click to expand...
I believe the 250ish range and above tends to be the sweet spot for SIGTORs, but don't quote me on that. That said, tornadoes can occur even in pretty pitiful SRH values, and summertime tornadoes can often kinda defy typical expectations for kinematics.
 
slenker said:
Do you mean effective shear values? Because I would definitely not call anything above 200 m2/s2 of 0-3 km SRH low shear (I see some >400 m2/s2 soundings in here too?) Maybe for violent tornadoes 200 m2/s2 is a little low, but that's still adequate for tornadogenesis.
Click to expand...
I'm talking about effective shear yes. SRH is storm relative helicity. Is that considered a form of shear too, because I thought they were separate things? I also thought 500 mb winds were sheer, and that's the biggest question mark with next week. I must be misinterpreting. 500 mb winds and low level jets are admittedly my weakest area of understanding.
 
Clancy said:
I believe the 250ish range and above tends to be the sweet spot for SIGTORs, but don't quote me on that. That said, tornadoes can occur even in pretty pitiful SRH values, and summertime tornadoes can often kinda defy typical expectations for kinematics.
Click to expand...
Yeah, I've heard of the outbreak Jarrell was involved in being a prime example of this. Pitiful low level kinematics, but the storm responsible for Jarrell was located at the cusp of the dryline "zipper" with the cold front to the west and stationary front to the north. That and the fact that there were many other tornadoes that day, including another violent one rated F4, which is very interesting.

Also, Moore 2013 was kinda like this too, but not as much because Moore 2013 was the result of a very localized jet streak that ended up enhancing the SRH in the absolute perfect spot compared to the surrounding environment, literally the worst possible thing that could have happened in such a confined corridor.

Grand Poo Bah said:
I'm talking about effective shear yes. SRH is storm relative helicity. Is that considered a form of shear too, because I thought they were separate things? I also thought 500 mb winds were sheer, and that's the biggest question mark with next week. I must be misinterpreting. That's admittedly my weakest area.
Click to expand...
It's totally understandable to misinterpret this, but yeah, SRH is considered a part of wind shear. Effective shear is technically a different thing, and all I know about it is higher values of effective shear are better for supercellular development/storm development in general. I think it also plays a role in how large supercells for a certain event may end up being. I could be wrong on this because I'm not a met, but I believe effective shear is basically the wind shear through the entire altitude of the atmosphere, while SRH is wind shear measured in the lower levels - at least that's my way of understanding it.
 
Last edited:
You must log in or register to reply here.
Back
Top