Severe Weather outbreaks

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I'm wondering if a QCLS will come to steal the show again, limiting tornado probability. They did mention that being a scenario for one of the days if I remember correctly
Prefrontal supercells will form before that would be able to happen. It can definitely overtake some supercells overtime though.

James Spann: "This is not good" "50% bracket for long track tornado analogs"
:stress:

1741754244471.png 1741754330749.png
Averaged sounding for nearly the entire open warm sector for Saturday.
(Low-resolution) discrete development is showing up on the operational models.
This is the real deal.

EDIT: EML (elevated mixed layer) is also present and a north-south oriented cold front which means even MORE discrete development.
Higher-resolution models in a few days will show a much clearer picture and I don't see them being any less impressive than what the GFS is showing now.
 
1741799522069.png
CSU-MLP is straight up showing a high risk for Saturday already.
1741799555411.png
Storm motion perpendicular to cold front orientation/motion, perfect for discrete development.
Models starting to show a secondary surface low to the south of the main low.
This looks awfully familiar to another tornado event in 2011...
 
View attachment 7083844
Storm motion perpendicular to cold front orientation/motion, perfect for discrete development.
Models starting to show a secondary surface low to the south of the main low.
This looks awfully familiar to another tornado event in 2011...
I'm gonna be completely honest I never really learned how to read these graphs
 
Yup, Friday and Saturday [and to some extent Sunday] are looking pretty froggy.

For Friday, March 14th:

Mar-14-2025-mdt-risk.gif
Overall risk for Friday.

Mar-14-2025-torprob.gif
Tornado probability for Friday.

Mar-14-2025-windprob.gif
Damaging wind probability for Friday.

And for Saturday, March 15th:

Mar-15-2025-mdtrisk.gif
Overall risk for Sat.

Mar-15-2025-probability.gif
Probabilistic risk for Sat.

1741855189262.png
Sunday, Mar 16th, too far out to really predict yet but it might do something.

Hopefully it ends up in a QLCS form rather than allowing discrete supercells to form because from what I've read all of the ingredients for tornadoes are present both days in large amounts. QLCS/squall lines sometimes produce little spin-up tornadoes but not typically anything too long-lasting or violent. Friday looks particularly likely to be derecho-y. Quite a few things could make either day a bust, like if some random pop up storms along the front sap some of the energy out of the air.

Again of course people are comparing it to the 2011 Super Outbreak which is fucking dumb, that was a once in a lifetime event. If you were alive and old enough to remember it clearly, you will likely not see another outbreak like that in your life. That was genuinely like playing GTA and putting in all of the most chaotic cheats at once, that's how primed the atmosphere was to fuck up Alabama. My rule of thumb is if James Spann is telling people to look out, it probably means business. The SPC doesn't hand out moderate risks very often and that 45% hashed area in the south is pretty rare to see too.

Hopefully it busts, this is that time of year where people get all excited about warmer weather but when it gets this warm that quickly in early March, it usually portends something ugly because there's so much moisture to work with.
 
Yup, Friday and Saturday [and to some extent Sunday] are looking pretty froggy.

For Friday, March 14th:

Mar-14-2025-mdt-risk.gif
Overall risk for Friday.

Mar-14-2025-torprob.gif
Tornado probability for Friday.

Mar-14-2025-windprob.gif
Damaging wind probability for Friday.

And for Saturday, March 15th:

Mar-15-2025-mdtrisk.gif
Overall risk for Sat.

Mar-15-2025-probability.gif
Probabilistic risk for Sat.

1741855189262.png
Sunday, Mar 16th, too far out to really predict yet but it might do something.

Hopefully it ends up in a QLCS form rather than allowing discrete supercells to form because from what I've read all of the ingredients for tornadoes are present both days in large amounts. QLCS/squall lines sometimes produce little spin-up tornadoes but not typically anything too long-lasting or violent. Friday looks particularly likely to be derecho-y. Quite a few things could make either day a bust, like if some random pop up storms along the front sap some of the energy out of the air.

Again of course people are comparing it to the 2011 Super Outbreak which is fucking dumb, that was a once in a lifetime event. If you were alive and old enough to remember it clearly, you will likely not see another outbreak like that in your life. That was genuinely like playing GTA and putting in all of the most chaotic cheats at once, that's how primed the atmosphere was to fuck up Alabama. My rule of thumb is if James Spann is telling people to look out, it probably means business. The SPC doesn't hand out moderate risks very often and that 45% hashed area in the south is pretty rare to see too.

Hopefully it busts, this is that time of year where people get all excited about warmer weather but when it gets this warm that quickly in early March, it usually portends something ugly because there's so much moisture to work with.
Wow. As I understand it, it's concerningly uncommon for a Day 3 Moderate to be on deck, and back-to-back Moderates on top of that is also a somewhat rare occurrence.

I agree though that this might not be as much of a tornado situation as it is damaging wind. Even so, if gusts are high enough, damaging wind can be just as destructive and disruptive as a tornado and should be handled just the same as if you were dealing with a tornado.

Regular reminder of safety tips for those of you who may be impacted:
  • The safest place you can be in the event of an emergency is the lowest floor of the building you're in (home or otherwise).
  • Small, windowless, interior rooms. Put as many walls between you and the outside as possible.
  • Prepare a SHTF bag just in case, be ready to include any important documents (ID, insurance, what have you), some suggest packing clean drinking water and non-perishable foods, batteries for devices, and your cell phone if you have one.
  • When taking cover, make sure you put on hard soled shoes and some form of head protection (helmet, hard hat, etc.) – pants and a jacket are also advisable to protect limbs from debris should the worst happen, either during or after the event.
  • If you happen to live in a trailer, mobile home, prefab, or other kind of manufactured home, DO NOT shelter within them in the event of a warning. Make a plan ahead of time to take cover at a local gas station, hotel, or any other kind of publicly accessible, sturdy site-built structure.
  • If any family or friends also may be impacted, pre-plan some manner of rendezvous should the worst happen – such as agreeing to meet up after the fact in a pre-designated location. Bear in mind communications may be impacted by storm damage, so it's good to plan ahead for some method of making sure everyone you care about is safe after the storm.
  • Have multiple ways to receive warnings so you can remain situationally aware. In the event of a Watch, monitor television stations, radio broadcasts, the internet (a lot of indie mets out there who tend to cover these events and local NWS offices will typically provide live updates for any current Warnings on their social media), your cell phone, and, if you have one, a NOAA weather radio. Any one method of staying informed has the potential to fail, so you want multiple ways to stay on top of the situation.
Also, one quick distinction:
  • A Watch is when conditions are currently favorable for the development of severe weather, typically within a 6-8 hour time frame (if not longer). Severe weather may not be imminent in your area during the duration of a Watch, but those within the Watch area should remain alert for rapidly-changing conditions. This is the time you should be keeping an eye on one or more of those ways to receive warnings.
  • A Warning is when severe weather has been observed, either by spotters or on radar, and the storms are currently occurring. This is the time you should be in cover. In some cases, you should be in cover well before the Warning is actually issued depending on your precautions. It is entirely possible for local NWS offices to MISS warning a particular storm that may have gone severe or a tornado under some circumstances (too many short-duration spin-up tornados which is common in a QLCS, bad radar data, a potential radar outage). Keep an eye on current weather conditions as well as storm progression, and, if need be, decide well and ahead of an issued Warning if you should enact your safety precautions ahead of time. This is especially important if you are not within a site-built structure.
Above all else, keep yourselves safe out there. Spring seems like it's coming in like a crackheaded lion this year.
 
A family relative of mines is kind of in a work meeting and vacation in Alabama. Thankfully, his vacation will take him to Florida before Saturday. Unthankfully, he can not take his dog with him, leaving him in a boarding daycare in Alabama until Sunday/Monday. What an unfortunate set of events.
Hopefully, Spring entering strongly like this means the weather will be nice and peaceful for a while until the next round.
 
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James Spann mentions the possibility for a few violent tornadoes. Link

1741898415415.png

MDT risk greatly expanded. Extremely strong wording in the Forecast Discussion, stuff you only ever see in HIGH risks. Wouldn't be surprised to see one on Day 1 or even Day 2.
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0230 PM CDT Thu Mar 13 2025

Valid 151200Z - 161200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS IN EASTERN
LA...MS...AND AL...

...SUMMARY...
A severe weather outbreak is expected on Saturday across the central
Gulf Coast States and Deep South into the Tennessee Valley. Numerous
significant tornadoes are possible on Saturday afternoon and
evening, centered on eastern Louisiana, Mississippi, and Alabama.
Widespread damaging wind swaths and scattered large hail are likely.

...Central Gulf Coast/Deep South/TN Valley...
Primary change is to expand level 4-MDT north in AL and all
categories west in the tight gradient of severe potential from the
Sabine to Lower MS Valleys. A particularly volatile scenario for
destructive severe remains evident during the afternoon to evening
on Saturday centered on the level 4-MDT risk region.

In the wake of the vigorous shortwave trough and very deep surface
cyclone crossing the North-Central States on D2, a broad upper
trough will linger across the southern Great Plains. An intense
mid-level jetlet, in excess of 100 kts at 500-mb, should eject
through the basal portion of this trough in south TX on Saturday
afternoon. This will induce secondary cyclogenesis along the
slow-moving baroclinic zone from the Ark-La-Tex to the central Great
Lakes. Another day of air mass modification ahead of this wave will
yield a pronounced plume of rich northwest Gulf moisture that should
be pristine across southeast LA into central MS through late
morning. As mid-level height falls overspread the diurnally warming
air mass, increasing convective development is expected along the
deepening baroclinic zone, as well as residual outflows to its
northeast in the TN Valley from prior late D2 convection.

Steep mid-level lapse rates atop the richly moist boundary layer
should yield at least moderate MLCAPE across the Lower MS Valley.
Vertically veering wind profiles with strong anvil-level divergence
amid the favorable instability should support robust updrafts and
intense supercells. Low-level shear will strengthen during the
afternoon and evening, setting the stage for a severe-weather
outbreak including significant tornadoes, damaging gusts, and large
hail. A pronounced dropoff in severe may be realized with northward
extent across the TN Valley as an emerging band and/or highly
organized line outpaces the rich Gulf air. Despite weaker
instability with eastern extent into GA/SC, the intense wind fields
may sustain damaging wind and embedded tornado potential well into
the overnight.

...OH Valley to Lower Great Lakes...
Forecast confidence is low with regard to severe potential north of
the TN Valley. Weakening late D2 convection should be in a decaying
process at 12Z Saturday. Much of the region will then be in between
waves until late afternoon. Guidance differs on the degree of
diurnal destabilization ahead of the deepening surface cyclone that
should track north-northeast from the Ark-La-Tex. It is plausible
that widespread Mid/Deep South to TN Valley convection during the
day Saturday will temper the northward extent of instability by
Saturday evening/night within a predominately meridional deep-layer
wind profile. As such, the overall severe risk appears conditional,
but given the fast flow regime, potential for damaging winds and
perhaps a few tornadoes may be realized.

..Grams.. 03/13/2025

Just wanna highlight these two lines.
Numerous significant tornadoes are possible on Saturday afternoon and evening, centered on eastern Louisiana, Mississippi, and Alabama.
A particularly volatile scenario for destructive severe remains evident during the afternoon to evening on Saturday centered on the level 4-MDT risk region.
 
Extremely strong wording in the Forecast Discussion, stuff you only ever see in HIGH risks. Wouldn't be surprised to see one on Day 1 or even Day 2.
I might be incorrect, or the standards might have changed recently, but generally High risks can't be issued until Day 1. If they go ahead and add it anyway on Day 2, though, that will definitely cement it as a threat to be taken seriously.
 
I might be incorrect, or the standards might have changed recently, but generally High risks can't be issued until Day 1. If they go ahead and add it anyway on Day 2, though, that will definitely cement it as a threat to be taken seriously.
It's happened before twice. One in 2006 and one in 2012. Day 3 they won't issue a high risk
 
Something to note is that both of those previous instances of Day 2 High risks happened under the old risk structure (Slight-Moderate-High), when consequently each risk tier was wider. There have been no Day 2 High risk areas under the new risk structure, as high risks can now be reserved for situations where significant outbreaks of severe thunderstorms are not just likely but certain.

So, if it happens tomorrow, it would demonstrate remarkable belief and trust in the forecasting models.
 
Wow, this is one hell of a way to start off tornado season. I'm in one of the moderate risk zones, and I had a feeling some nasty storms were on their way from just the sheer humidity in the air over the last day or two. Hopefully it'll blow through quickly, but I'm gonna pop some new batteries into my weather radio and put together a SHTF bag just in case.
 
Wow. As I understand it, it's concerningly uncommon for a Day 3 Moderate to be on deck, and back-to-back Moderates on top of that is also a somewhat rare occurrence.
Yeah, it's definitely not too common and there is some chance that Saturday gets upgraded to a tornado-driven high risk which is quite rare, maybe 2-3 times a year you'll see a high risk and it's usually good ol' straight line winds that drive it. Day 3 moderate risk means they have very high certainty that shit is going to hit the fan. Also definitely agree on straight line winds being just as [if not more so] damaging and disruptive as tornadoes. Sure, tornadoes fuck shit up worse but they are extremely localized. One house is gone and the house next to it is missing a few shingles but otherwise fine, sturdy, habitable. Straight line winds? That shit can basically render an entire region or portion of a state impassable until all the power lines, poles, trees, limbs, debris are cleaned up and everybody is likely to be without power for 2-3 days at least, telecom lines down, etc. If it gets up to 90-100mph you will start seeing damage to well-built homes and vehicles, mobile homes don't fare too well but when do they ever? Anyone who doubts the amount of trouble straight-line winds can cause, I would encourage them to look into the 2020 Cedar Rapids derecho in Iowa, or the derecho that happened just last year in Houston.

So basically nobody should assume just because the tornado risk is low that it's nothing to worry about, straight line winds do just fine fucking up shit on their own without the help of Cousin Tornado. I always hope for a bust but this one doesn't look like it's going to, that southern portion is going to be a real cranky bitch when she gets going and the big wind event in Iowa/Illinois/Missouri isn't going to be a picnic either. One good thing is that in either case, these storms are going be moving FAST which means it's not going to be an all day event, they'll come in and be gone within an hour or two.
 
1741932498476.gif

Confidence in tornadoes has increased for day 1 within a corridor in Missouri/Illinois. No major change made to Saturday's outlook, double MDT upheld for now.
 
Day 1 Outlook (06Z Update)
1741932391535.png

Valid 141200Z - 151200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS THE
MID-MISSISSIPPI VALLEY AND PORTIONS OF THE LOWER OHIO VALLEY...

...SUMMARY...
A regional outbreak of severe storms is likely across the
Mid-Mississippi Valley to the Lower-Mississippi Valley, including
portions of the Lower Ohio Valley. Tornadoes, several of which could
be strong, widespread damaging winds with gusts from 70 to 90 mph,
and scattered large hail up to baseball size will be possible.

...Discussion...

Satellite imagery depicts a well-defined upper trough over the
southwestern U.S./northwest Mexico. This feature is forecast to
advance into the southern Rockies by sunrise as a 115kt 500mb speed
max translates across southern NM. This jet max should increase to
near 125kt as it translates into southwest OK by 18z, then weaken to
near 100kt overnight over northern IL. Water-vapor/radar data
suggest the leading edge of large-scale forcing is currently
spreading across western NM. Latest model guidance suggests intense
12hr mid-level height falls (on the order of 240-270m) will spread
across the southern Plains into IA as left-exit region of the
aforementioned jet shifts into the mid-MS Valley. At the surface, a
pronounced dry line will surge across the central Plains, arcing
from a very deep surface low over northwest KS-eastern OK by 18z.

Strong boundary-layer heating is forecast ahead of the cyclone, and
convective temperatures will easily be breached as temperatures warm
into the lower 70s. While surface dew points will remain a bit low,
SBCAPE should exceed 1000 J/kg and robust convection will readily
develop along the wind shift. Of particular concern will be the
efficiency of mixing very strong flow downward within this
convection. Forecast soundings exhibit 50kt just off the surface,
and very steep lapse rates will prove favorable for severe gusts
with any convection today. Widespread wind damage, with speeds
likely exceeding 70 mph are expected. Severe squall line should
organize and surge northeast across the mid-MS Valley during the
afternoon/evening hours.

Farther southeast, LLJ is forecast to strengthen markedly across
eastern AR/MO into IL. This will allow somewhat higher
boundary-layer moisture to advance across the lower into the middle
MS Valley prior to thunderstorm development. Latest thinking is
supercells should develop ahead of the fast-moving 500mb speed max,
with some propensity for activity lingering across the mid-South as
the right-entrance region of the jet influences longevity of
convection. Forecast soundings strongly favor organized convection
with supercells expected. Higher moisture content into eastern
MO/southwest IL will contribute to higher tornado probabilities with
these strongly sheared supercells. Longer-lived updrafts may produce
strong tornadoes, in addition to very strong winds and large hail.

Southern extent of the regional outbreak will likely be influenced
by the lack of stronger forcing across the lower MS Valley. Even so,
isolated severe supercells are expected within the less-forced
environment. This activity may linger well into the overnight hours.

..Darrow/Moore.. 03/14/2025

Mainly a wind-driven threat, but several significant (EF2+) tornadoes are still expected across the risk.



Day 2 Outlook (06Z Update)
1741932489974.png

Valid 151200Z - 161200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
LOUISIANNA...MISSISSIPPI...ALABAMA AND THE FLORIDA PANHANDLE...

...SUMMARY...
A tornado outbreak is possible on Saturday across the central Gulf
Coast States and Deep South into the Tennessee Valley. Numerous
significant tornadoes, and some long-track tornadoes are expected on
Saturday afternoon and evening, centered on eastern Louisiana,
Mississippi, and Alabama. Widespread damaging wind swaths and
scattered large hail are likely.

...Tornado Outbreak Possible Across parts of the Southeast on
Saturday...
...Gulf Coast States/Tennessee Valley/Southern
Appalachians/Georgia...
At mid-levels on Saturday, a strong and fast-moving jet streak will
translate eastward across the southern U.S., as an associated trough
moves through the Great Plains. Ahead of the system, a moist and
unstable airmass will be in place across the lower to mid
Mississippi Valley. Warming surface temperatures in the morning will
contribute to the development of moderate instability across much of
the moist airmass. As large-scale ascent increases ahead of the
approaching jet streak, scattered thunderstorms are expected to
initiate near the western edge of the moist airmass during the late
morning, from eastern Louisiana into northwest Mississippi and
western Tennessee. These storms should become severe rather quickly
due large-scale forcing, moderate instability and strong deep-layer
shear. Supercells with large hail, wind damage and a tornado threat
are expected to develop and move east-northeastward during the
afternoon across the central Gulf Coast States and Tennessee Valley.

The exit region of the mid-level jet streak is forecast to move
across the lower Mississippi Valley and Tennessee during the mid to
late afternoon, which will be timed well with afternoon max heating.
Forecast soundings at 21Z across parts of southern and central
Mississippi have MLCAPE in the 2000 to 3500 J/kg range, with 0-6 km
shear of 70 to 80 knots. 700-500 mb lapse rates are forecast to be
near 8 C/km, with 0-3 km storm-relative helicity in the 400 to 500
m2/s2 range. This will be very favorable for intense severe storms,
with a threat for tornadoes, wind damage and large hail. Several
tornadic supercells are expected to develop within this cluster by
mid to late afternoon as the low-level jet intensifies. Multiple
long-track high-end tornadoes will be possible. The greatest tornado
threat is expected to shift into Alabama by early to mid evening,
with a significant tornado threat also impacting parts of middle
Tennessee. In addition, supercells are expected to grow upscale into
a developing MCS, with potential to produce significant severe wind
gusts above 70 knots and large hail. The severe threat is expected
to develop eastward into parts of Georgia and the southern
Appalachians by mid to late evening. A severe threat should continue
into the overnight.

...Ohio Valley/Lower Great Lakes...
A negatively-tilted mid-level trough will move into the western
Great Lakes on Saturday, as the southern part of the trough moves
into the mid to upper Mississippi Valley. Ahead of the system,
southwest mid-level flow will be in place over most of the Great
Lakes and Ohio Valley. At the start of the period, a corridor of
rich low-level moisture is forecast from western Kentucky northward
into Indiana. Surface dewpoints along this corridor will likely
range from the mid 50s to the lower 60s F. Early in the period, a
cluster of strong thunderstorms is forecast to move across the Ohio
valley. Some of the storms could have severe potential. Wind damage,
isolated large hail and a few tornadoes will be possible. In the
wake of this activity, outflow could negatively affect the airmass
over parts of the Ohio Valley. However, areas that are not affected
by outflow could re-destabilize, maintaining a severe threat. As the
exit region of a mid-level jet moves across the Ohio Valley and
lower Great Lakes during the late afternoon, supercells will be
possible due to the increasing large-scale ascent and strong
deep-layer shear. Any supercell could have potential for tornadoes,
wind damage and hail.

..Broyles.. 03/14/2025

Tornado-driven threat with, in my opinion, an upgrade to a high risk likely in subsequent updates.
Extremely strong wording being used as well.
Multiple long-track high-end tornadoes will be possible.
This one sticks out to me particularly. They never use the word high-end when describing tornado intensity.
 
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