Severe WX March 26th-27th, 2023

[JBishopwx]

Not sure if i need to post this here or in the Severe Weather 2023 chat but there is a slight risk for Sunday.

 

[Taylor Campbell]

Thread to discuss tomorrow's severe weather threat.

 

[KevinH]

Thanks. The title of the other thread (March 23-26) might need to be modified.

 

[Taylor Campbell]

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1123 AM CDT Sat Mar 25 2023

...Alabama...
The residual outflow boundary draped across the Southeast from prior
convection over the past 24 hours is expected to gradually lift to
the north through the day, eventually becoming draped from southeast
LA into southern MS and central AL by late tonight. A weak mid-level
perturbation is expected to move into the southern Plains/lower MS
River Valley during the 00-12 UTC period, which will help strengthen
southerly 850 mb flow and bolster isentropic ascent over the
boundary. Despite some nocturnal cooling, profiles are expected to
be weakly capped with MLCAPE values near 1000-2000 J/kg during the
overnight period. Elongated hodographs featuring around 50 knots of
effective shear should support organized cells, including splitting
supercells, that will pose a severe wind/hail risk (though storm
motions along the boundary may limit individual cell longevity and
promote upscale growth into clusters). Timing of this convection
remains uncertain with recent CAMs showing spread in the onset of
convective initiation, but the probability of CI prior to 12 UTC has
increased sufficiently to introduce higher risk probabilities.

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1246 AM CDT Sat Mar 25 2023

Valid 261200Z - 271200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EXTREME EAST
TEXAS INTO CENTRAL LOUISIANA...CENTRAL/SOUTHERN MS/AL...CENTRAL GA
AND A SMALL PART OF SOUTH CAROLINA...

...SUMMARY...
Severe thunderstorms are possible from far east Texas and central
Louisiana into southern and central Mississippi, Alabama, and
Georgia on Sunday. Large hail, damaging gusts and a couple tornadoes
appear possible.

...Lower MS Valley/Southeast Vicinity...

A challenging forecast scenario exists for Sunday across portions of
the South. While some model variability still exists, consistency is
better than 24 hours ago and an increase in severe probabilities
appears warranted.

A broad upper trough will envelop much of the CONUS, with a swath of
fast deep-layer southwesterly flow stretching from the southern
Plains through the southern/central states and the Eastern Seaboard.
Large-scale ascent will remain somewhat nebulous with little
opportunity for height falls. However, most guidance shows a series
of weak shortwave impulses migrating through larger-scale flow from
TX toward the Carolinas. A compact upper shortwave trough over the
southern Plains will migrate toward Mid-MS Valley overnight.

A stalled surface front is expected to extend from coastal NC into
central GA Sunday morning. The location of the western portion of
this boundary is uncertain, with guidance varying from southern
AL/MS/LA to northern AL/MS/LA. Nevertheless, southerly low-level
flow and warm advection should allow the boundary to drift northward
during the day, spreading mid-60s F dewpoints across the region.
Additionally, a plume of steep midlevel lapse rates is forecast to
overspread the region. Where pockets of stronger heating occur,
MLCAPE values around 1000-1500 J/kg are expected.

Some convection will likely be ongoing Sunday morning across GA into
the Carolinas as an initial shortwave impulse shifts east/northeast
over the area. Strong gusts will be possible with bowing segments.
Additional thunderstorms are expected to develop further west in the
vicinity of the northward retreating warm front during the
afternoon/evening. Low-level winds will be rather light, though
quickly increase with height above 850 mb. Furthermore, a low-level
jet is forecast to increase to around 35-45 kt during the evening.
Vertical wind profiles will be largely unidirectional, and may
support training convection/heavy rain, tempering the overall severe
threat. However, some guidance shows enough speed/directional shear
in the low level to foster enlarged and favorably curved hodographs
in the vicinity of the warm front. Effective shear magnitudes
greater than 40 kt also will promote organized convection. All
severe hazards appear possible with more intense, sustained storms.
However, weak low-level shear and largely boundary-parallel shear
vectors may lead to more transient supercell structures. While
uncertainty still remains, the overall parameter space supports a
Slight risk.

..Leitman.. 03/25/2023

 

[KevinH]

Adding the post from @Clancy from the other thread.

Post in thread 'March 23-26th, 2023'
https://talkweather.com/threads/march-23-26th-2023.2100/post-91176

 

[KevinH]

Next D2 update should be out ANY minute…

 

[Taylor Campbell]

CSU-MLP max tornado prob almost to 10% with the 12z run and Nadocast shows 10% in the same region. Maxwell radar being down may be a problem tomorrow.

 

[South AL Wx]

Enhanced risk issued for tomorrow due to a 30% hatched hail risk.

 

[Taylor Campbell]

The HRRR model shows very robust lightning activity with the thunderstorms.

 

[WesL]

Thanks. The title of the other thread (March 23-26) might need to be modified.

Done and done. This is a little different. I know in the past I had said let's keep them together if they are hours apart, but this is a full day, and there is a lot of analysis going on in the other thread. Thanks for the suggestions, everyone.
What we voted on was long duration (weeks+) events.

Noting to get out of shape on. Just talk about the weather and we will sort out the topics and move things around.

 

[Weatherphreak]

I'm heading to Bham tomorrow night for a concert. I'm interested to see how far north the severe threat gets? Looks like Alabaster south is where the threat ramps up on these maps.

 

[KevinH]

Done and done. This is a little different. I know in the past I had said let's keep them together if they are hours apart, but this is a full day, and there is a lot of analysis going on in the other thread. Thanks for the suggestions, everyone.
What we voted on was long duration (weeks+) events.

Noting to get out of shape on. Just talk about the weather and we will sort out the topics and move things around.

Alright. Analysis for more than one event/system (even if hours apart) in the same thread can cause confusion and make things difficult when looking through the list of threads.

That’s why I saying each system should have its own thread. If that SAME system ends up producing several days (like an outbreak/outbreak sequence), then a thread covering multiple days is more practical.

Thank you for updating the titles!

 

[KevinH]

@Clancy posted this in the other thread.

Would someone explain THIS and how that squares with the 5% TOR risk for tomorrow?

 

[Clancy]

Would someone explain THIS and how that squares with the 5% TOR risk for tomorrow?

Most of the CAMs depict a body of convection, probably a QLCS, moving through Central and Southern AL/GA during the morning into around the noon hour on Sunday, followed by a second round (not all the CAMs are on board with this part of the day) later that evening into the morning hours on Monday. A wedge is modelled to limit the northern extent of destabilization, though it looks like some storms in the later round may ride just south of that boundary. Not the same type of risk we saw yesterday but could certainly bring some nasty winds and some tornadoes.

 

[Clancy]

00Z HRRR has significantly expanded northward areal extent of instability tomorrow evening. Also keep an eye out for tonight's storms if you're in South/Central AL/GA, could pack some winds and probably a lot of lightning.

 

[CheeselandSkies]

I wouldn't sleep on some strong tornado potential with the storms tomorrow. Low-level curvature in the hodographs isn't nearly as large as it was yesterday, but with that amount of instability it should be enough.

 

[buckeye05]

Question. Is tomorrow’s potential event part of the same system that produced the 24th/25th tornadoes, or from a separate weather system? Trying to settle some confusion right now and I don’t know the answer for sure.

 

[OHWX97]

 

[MattPetrulli]

Question. Is tomorrow’s potential event part of the same system that produced the 24th/25th tornadoes, or from a separate weather system? Trying to settle some confusion right now and I don’t know the answer for sure.

Same system, just has a stationary front. I like this setup a decent bit

 

[buckeye05]

Getting big “sleeper tornado day” vibes from tomorrow’s setup.