• 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 WX Severe Weather Threat 3/14-3/16

Yeah, I'll pass on that. Day 5 SPC says "multiple rounds of convection, 'mix of supercells and QCLS' " what're we looking at a all day morning to night severe/tornado threat in Alabama?

Hate to say it, but we are back too looking REALLY bad for Alabama. Supercell composite is very high again. And the GFS Is on that favorite low pressure Track for tornado outbreaks in the south. Screenshot_2025-03-11-05-02-54-65_40deb401b9ffe8e1df2f1cc5ba480b12.jpg
 
Last edited:
Grand Poo Bah said:
Wouldn't higher CAPE, by its very nature, prevent the formation of a squall line? Can the atmosphere really form something linear in so much instability? Got a little curious, and did some digging. This study says the average Springtime QLCS forms in 500-2000 CAPE. 3500 J/kg would blow that out of the water (literally).

I also want to re-highlight A comment I posted in the Severe Weather Megathread, because it feels especially relevant now.



I think people (and models) could be underestimating the type of highly atypical and powerful ingredients we're sending from up here in the north to the Dixie Alley.
Click to expand...
Deep-layer shear vector orientation with respect to boundaries, vertical wind profile structure, and capping strength play the biggest role on storm mode. If your thinking was correct about higher CAPE, your local area would never see the late spring and summer MCS/derecho events. They would all be supercells because of high CAPE. Not how it works...
 
I'm starting to think the Euro is overturning its EML and just over-convecting on Saturday just because reasons. It's had a bad problem with that for a good 3+ years now, off and on, with systems here. It's shown many overturned warm sectors or coastal complexes in the medium range that never ended up happening. Given the general low amplitude nature of the flow, the mid-level source region of the flow tracking back to drought areas to the west/southwest, and robust moisture return Friday delaying until the overnight to our west for the most part, I'm starting to think this may be another one of those cases. The GFS has been course-correcting with the synoptic layout... trending a bit broader with the Saturday trough and nudging northwest, shifting a bit west with the Great Lakes low to allow a warm sector that stands up. It's trended closer to the Euro with the larger-scale, but I think it's handling the EML/capping better. I still think there is Friday late night potential for trouble up here in northwest AL / southern TN / northeast MS, but this is taking Saturday in a potentially volatile direction for about the eastern 1/2 to 2/3 of MS, most of AL, west and north-central GA, and southern middle TN.
 
Still splitting run to run hairs at this point but it looks like 06Z GFS is a slight improvement for thermodynamics on the north end of Friday's setup, not necessarily higher dewpoints but suggesting less of a nuclear cap that might be breakable sometime between 23-01Z given the strong forcing in the exit region.
 
I’m gonna keep it a buck 50 with you guys.

Saturday looks like a greater substantial threat than Friday by an order of magnitude.

Firstly, far more agreement between global models, the CMC and AI Euro also have the same scenario.
1741691900045.png1741691949453.png
The broad troughing to the southwest of the surface low creates enough height falls to generate a weak vort max in the PBL. This weak vort max causes a very strong LLJ by Saturday afternoon. Combine this with the enhanced moist air advection from the present surface low, then you have dew points in the high 60s to 70s. What you have is the very rare scenario of having a strong LLJ directly overlapping high cape by the afternoon hours.
1741692356223.png1741692401697.png
This sounding in central Mississippi is the result product of such a thing. You guys know what most of these parameters mean so nothing needs to said about these numbers other than they’re what create significant tornado outbreaks.

But look at the depth of that effective inflow layer along with the highly streamwise vertical wind profile in the PBL, this is the setup that causes supercells to become tornadic quickly.

The upper level jet can be marked out here, and it’s almost perpendicular to the PBL flow, which is prime for discrete storm mode development.

Also, look at the vertical temp/dew point profile, pretty much completely moist from top to bottom up to the EL.
Notice the inversion layer, it’s weak enough to allow any remotely powerful updrafts though and go to town while strong enough to deny crapvection.

And if you guys noticed earlier looking at the 500mb vorticity, you’ll realize this trough setup has forcing that’s weak enough to not generate a messy storm mode, but strong enough for plentiful convection to actually occur in the OWS.
1741692002394.png
This is honestly making me feel a little dreadful, hopefully things downtrend from here.
 
jiharris0220 said:
I’m gonna keep it a buck 50 with you guys.

Saturday looks like a greater substantial threat than Friday by an order of magnitude.

Firstly, far more agreement between global models, the CMC and AI Euro also have the same scenario.
View attachment 34991View attachment 34992
The broad troughing to the southwest of the surface low creates enough height falls to generate a weak vort max in the PBL. This weak vort max causes a very strong LLJ by Saturday afternoon. Combine this with the enhanced moist air advection from the present surface low, then you have dew points in the high 60s to 70s. What you have is the very rare scenario of having a strong LLJ directly overlapping high cape by the afternoon hours.
View attachment 34994View attachment 34995
This sounding in central Mississippi is the result product of such a thing. You guys know what most of these parameters mean so nothing needs to said about these numbers other than they’re what create significant tornado outbreaks.

But look at the depth of that effective inflow layer along with the highly streamwise vertical wind profile in the PBL, this is the setup that causes supercells to become tornadic quickly.

The upper level jet can be marked out here, and it’s almost perpendicular to the PBL flow, which is prime for discrete storm mode development.

Also, look at the vertical temp/dew point profile, pretty much completely moist from top to bottom up to the EL.
Notice the inversion layer, it’s weak enough to allow any remotely powerful updrafts though and go to town while strong enough to deny crapvection.

And if you guys noticed earlier looking at the 500mb vorticity, you’ll realize this trough setup has forcing that’s weak enough to not generate a messy storm mode, but strong enough for plentiful convection to actually occur in the OWS.
View attachment 34993
This is honestly making me feel a little dreadful, hopefully things downtrend from here.
Click to expand...
And Friday late and overnight starting to like no picnic either … lower level jet screaming with increased cape for Friday afternoon. Afraid the 6zgfs has started the up trend even
 
Just getting caught up this morning, but my feelings have not changed from last night. In fact, I'm starting to get that dreadful feeling that @MichelleH often speaks of. All signs point to a volatile setup for the Southeast. I fear this could shape up to be one of the most dangerous events Georgia has seen in a number of years.
 
Clancy said:
Just getting caught up this morning, but my feelings have not changed from last night. In fact, I'm starting to get that dreadful feeling that @MichelleH often speaks of. All signs point to a volatile setup for the Southeast. I fear this could shape up to be one of the most dangerous events Georgia has seen in a number of years.
Click to expand...
You jinxed us earlier in the thread when you mentioned we often get skipped over.
 
keithGA said:
You jinxed us earlier in the thread when you mentioned we often get skipped over.
Click to expand...
As a resident of north Forsyth county for the last 15 years, I don’t believe we’ve had any significant tornadoes in North Central GA in some time. I believe there was an f3/f4 that went through North Dawson county/Dahlonega back during the Palm Sunday outbreak in 1994. Have there been any strong/significant tornadoes since then?
 
aujerm said:
As a resident of north Forsyth county for the last 15 years, I don’t believe we’ve had any significant tornadoes in North Central GA in some time. I believe there was an f3/f4 that went through North Dawson county/Dahlonega back during the Palm Sunday outbreak in 1994. Have there been any strong/significant tornadoes since then?
Click to expand...
1741697532538.png
F3 or greater intensity tornadoes from the day after the Palm Sunday 1994 outbreak through the end of 2023.
 
Saturday looking increasingly custom tailored to be a bad day for a lot of people; could always throw a fail mode or two in the mix but that's about the highest ceiling we have seen in quite a while
 
You must log in or register to reply here.
Back
Top