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2/15/25 SE Severe Threat

Kds86z said:
Curious as Trey doesn’t see a bullish tornado threat compared to SPC. He’s been right before..View attachment 33787
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Here is what I see (I admittedly do not know anywhere near as much as Trey does at this point of my education).

1. Dew points are very high. Dew point depression numbers are less than 5 F for pretty much all of the threatened area. Moisture will not be a limiting factor in the slightest.
2. Lots of shear. Even relatively weak updrafts could spin up a small tornado with the amount of shear that is present.
3. HRRR shows a clear warm sector. Any potential rain threats are out of most of MS well in advance of the main line. I actually am not as bullish on the Memphis metro being a 10% hatched risk. I think that the rain moving through will stabilize the atmosphere a decent bit.
4. Models seem pretty set on supercells in front of the QLCS. Having to worry about both threats is a big deal.
5. High STP values and high helicity values (which is related to the shear).
6. Enough CAPE for this time of the year.

I said a couple days ago I expected a MDT for ArkLaMiss and I'm sticking by that comment. Just about any point in the MS delta has a classic tornado sounding.

I am also an anonymous poster on a weather forum and not working for the NWS. So take these things with a grain of salt. Just figured I'd try to start explaining my reasoning now that I know a couple of things instead of just saying "I expect this to happen" without providing any reason why. My analysis could (and probably will be) way off.

Here is a sounding basically right on the MS river where MS/LA/AR meet. (HRRR 22Z)

hrrr_2025021506_016_33.02--90.93.png
 
The area covered with the 10% tornado risk is very large lol. Again we may have a tornado outbreak just on spinups this evening and night.

Something I am concerned about is that if this line can remain semi broken we may have a couple of longer lived significant tornadoes. But I think the safest bet at the moment is a event heavy on spinups and QCLS damaging winds.
 
Dangerous day/night ahead...

...SUMMARY...
Severe thunderstorms are expected from parts of far east Texas into
much of the lower Mississippi Valley and Southeast. Several
tornadoes and scattered to numerous damaging wind gusts should be
the primary threats. A few strong tornadoes are also possible.
Intense thunderstorms should develop by late this afternoon and
continue through the overnight hours.

...East Texas into the Lower Mississippi Valley and Southeast...
Strong low-level warm advection has encouraged elevated
thunderstorms early this morning from parts of AR into the Mid-South
and TN Valley. This activity should remain sub-severe, with poor
mid-level lapse rates hindering updraft strength and hail potential.
A pronounced upper trough over the Southwest this morning will eject
eastward across the southern/central Plains today, eventually
reaching the MS/OH Valleys and Southeast late tonight. A broad area
of surface low pressure is forecast to consolidate through the day,
with the primary surface low expected to deepen as it develops
east-northeastward across the Mid-South and lower OH Valley this
evening. An attendant cold front will eventually move
east-southeastward over the lower MS Valley and much of the
Southeast this evening and overnight.

Ahead of the approaching upper trough and deepening surface low,
low-level moisture will continue to stream northward across the
lower MS Valley. While lapse rates aloft should remain fairly
modest, filtered daytime heating and low-level moistening will aid
in the development of around 500-1000 J/kg of MLCAPE by mid to late
afternoon. Current expectations are for robust, surface-based
thunderstorms to develop by 20-22Z along or just ahead of the cold
front from far east TX towards the Mid-South. While this activity
may initially be supercellular, nearly all guidance suggests a quick
transition to a more linear mode by early evening. Even so, very
strong 0-3 km shear, aided by a 45-55+ kt low-level jet, will easily
aid updraft rotation and organized severe thunderstorms.

Ample low-level shear will support a threat for several
line-embedded tornadoes from late this afternoon through early
Sunday morning. The potential for supercells ahead of the line
remains unclear. But, any supercells embedded within the line could
produce strong tornadoes given the enhanced low-level shear.
Otherwise, scattered to numerous severe/damaging winds will likely
occur with the line of convection as it spreads eastward across the
Mid-South, TN Valley, and central Gulf Coast states this evening and
overnight. Isolated significant severe gusts appear possible where
the best overlap of strong low/mid-level flow and adequate buoyancy
is forecast, mainly across parts of the ArkLaMiss into western TN.
Some adjustments have been made to the Enhanced and Slight Risk
areas to account for latest guidance trends, including across parts
of AL/GA where a threat for tornadoes and damaging winds will likely
continue through the end of the period as the line advances eastward
in a weak but sufficiently unstable airmass.

..Gleason/Broyles.. 02/15/2025
 
Looking at the latest data, this is looking like a very bad day. Anyhow, I could care less about the total number of tornadoes for a "outbreak" to verify. My main job is to get the message out in a simple but concise form for people to understand without the hype and hope there's no significant damage and/or loss of life.
 
I'm a weather illiterate so I can't comment much on the ongoing topic but you guys are great at explaining the upcoming events. Reading here and googling the things I don't understand really helps and I may learn over time. I've been hit in the head a lot so I may not. We'll just have to see.
 
CAM signal seems to be suggesting a risk of more of a broken line with embedded supercells in part of the 12z guidance. Definitely something to look out for. Not expecting proper pre-frontal supercells but certainly a QLCS and semi-discrete/embedded mesocyclone risk which will pose a threat of strong tornadoes.
 
JPWX said:
Looking at the latest data, this is looking like a very bad day. Anyhow, I could care less about the total number of tornadoes for a "outbreak" to verify. My main job is to get the message out in a simple but concise form for people to understand without the hype and hope there's no significant damage and/or loss of life.
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Beautifully said my man.
 
UK_EF4 said:
CAM signal seems to be suggesting a risk of more of a broken line with embedded supercells in part of the 12z guidance. Definitely something to look out for. Not expecting proper pre-frontal supercells but certainly a QLCS and semi-discrete/embedded mesocyclone risk which will pose a threat of strong tornadoes.
Click to expand...
I feel like we should get a closer idea of what the day is gonna unfold like as we get closer to Noon.
 
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