2/15/25 SE Severe Threat

SPC still holds a large 15% area for Day 5 (Saturday) and says the tornado threat will depend on discrete development ahead of the front. Remember, we are still in winter and it does not take as much instability to have a very, very bad day.

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...Day 5/Saturday...
A strong trough, which has trended more amplified in the ECMWF, is
expected to impact the Sabine Valley into the Southeast starting in
the afternoon. The latest model trends also have a more favorable
placement of the surface low in the Tennessee Valley. These factors
will drive strong moisture advection into the region by Saturday
morning, continuing into Sunday. Intense wind fields throughout the
column will support organized storms capable of all hazards.
Damaging winds, particularly with linear convection along the strong
cold front, currently appears as the main threat. The magnitude of
the tornado threat will largely depend on discrete development ahead
of the front. Given the moist environment with minimal inhibition
and strong forcing, that scenario is certainly plausible. Discrete
development or not, low-level wind fields still will support
line-embedded circulations. Despite more limited buoyancy farther
north, the strongly forced convective line and 60-70 kts of 850 mb
flow would support damaging winds even in shallow convection.
Uncertainties still remain along the fringes of the highlighted area
(i.e., how far west will convection form, how unstable will it be to
the north/east). Mid-level lapse rates will also not be overlay
steep. Even so, the overall pattern continues to support the
potential for scattered to numerous severe storms.
 
UK_EF4 said:
Seen some talk online (not here) at about how this event seems lacklustre or unimpressive… but I would definitely disagree.

Latest GFS run brings nearly 2000j/kg of SBCAPE into parts of MS,LA, AR on Saturday. Yes it’s just one run, but this is the GFS… at 4/5 days range… in winter. Kinematic seem unlikely to be a major issue. Meanwhile the trough ejection and geometry seems to be trending more favourable.

A lot can and often does change in 110-120 hours of weather forecasting, but this one certainly seems worth watching closely regardless.
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I mean, if memory recalls, Dec 28th looked kinda bad, then around d2-3 everything casted mega uptrend. Wx forecasting in a nutshell.
 
GFS has been trending slower over the past few runs with when the jet streak rounds the base of the trough, and instability has downtrended slightly.
 
Main trends I'm noticing based on the models are (some already mentioned by @Jason Mills above)...
  • A slower and more amplified trough - I generally think this heightens the severe threat, unless things go too far and forcing is way too strong.
  • A more broad warm sector, opening up to the NE and less pinched off. Undoubtedly increases severe risk, especially any pre-frontal threat, though admittedly a little early days for that.
  • Trend from SW to S flow across the Gulf of Mexico, which are likely to increase depth/speed of moisture profiles
  • Slight backing trend in the LLJ, may enhance low level shear.
  • Slight decrease in instability - perhaps related to lapse rates?

In general I think at this stage its better to focus on broad synoptics and trends, and not get overhyped given how much can/will change. But I must say this event definitely has a high ceiling at this stage, especially if trends continue heading in the broad direction they've gone in the last 24 hours.

trend-gfs-2025021112-f108.500wh.conus.giftrend-gfs-2025021112-f108.sfctd_b-imp.conus.gif
 
UK_EF4 said:
Main trends I'm noticing based on the models are (some already mentioned by @Jason Mills above)...
  • A slower and more amplified trough - I generally think this heightens the severe threat, unless things go too far and forcing is way too strong.
  • A more broad warm sector, opening up to the NE and less pinched off. Undoubtedly increases severe risk, especially any pre-frontal threat, though admittedly a little early days for that.
  • Trend from SW to S flow across the Gulf of Mexico, which are likely to increase depth/speed of moisture profiles
  • Slight backing trend in the LLJ, may enhance low level shear.
  • Slight decrease in instability - perhaps related to lapse rates?

In general I think at this stage its better to focus on broad synoptics and trends, and not get overhyped given how much can/will change. But I must say this event definitely has a high ceiling at this stage, especially if trends continue heading in the broad direction they've gone in the last 24 hours.

View attachment 33535View attachment 33536
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agreed, I am still iffy cuz of lapse rates, however if those increase then game on and we have an issue.
 
I'm intrigued to see the nam gets in range. And how bullish the coverage of any open warm sector storms there will be, not to downplay any QCLS rotations. You'll see your usual uptick in thermodynamics, if a slowing trend continues Mississippi will be your peak area for the threat although Alabama will be in good position for some nocturnal stuff.
 
Parker Copeland said:
agreed, I am still iffy cuz of lapse rates, however if those increase then game on and we have an issue.
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Yep agreed. If lapse rates increase, and the trough continues to trend towards not being displaced too the north of the WS, I could see this becoming outbreak level. Obviously a lot has to come together for that to happen in the first time, though.
 
UncleJuJu98 said:
I'm intrigued to see the nam gets in range. And how bullish the coverage of any open warm sector storms there will be, not to downplay any QCLS rotations. You'll see your usual uptick in thermodynamics, if a slowing trend continues Mississippi will be your peak area for the threat although Alabama will be in good position for some nocturnal stuff.
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yeah, these kinds of events are typically longer in nature from the qlcs + pre-frontals and then the renewed nocturnal threat from LLJ increasing
 
UK_EF4 said:
Wow. Do you happen to recall the last event probabilities were so elevated?
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Personally I do not; I'm sure we've had plenty of events with those kinds of probs on CIPS in the past few years, but for them to be that pronounced definitely strikes me as a very strong signal.
 
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