Severe WX March 26th-27th, 2023

[MattPetrulli]

better LLJ placement, cleaner WS, later initiation, and northward trend with WF


wouldn't be shocked to eventually get a 10 or 10#

 

[andyhb]

"Beware the westerly flow events in the SE."

 

[MattPetrulli]

"Beware the westerly flow events in the SE."

4/19/20 with better storm mode but less shear and slightly less instability

 

[jiharris0220]

This could potentially catch a lot of people off guard.
These extreme SE events are notorious for their surprise tornado outbreaks.

 

[buckeye05]

4/19/20 with better storm mode but less shear and slightly less instability

Was gonna say the same. Definitely some similarities.

 

[Taylor Campbell]

638
ACUS11 KWNS 260341
SWOMCD
SPC MCD 260340
ALZ000-MSZ000-260615-

Mesoscale Discussion 0344
NWS Storm Prediction Center Norman OK
1040 PM CDT Sat Mar 25 2023

Areas affected...parts of southern into central Alabama

Concerning...Severe potential...Watch possible

Valid 260340Z - 260615Z

Probability of Watch Issuance...40 percent

SUMMARY...Rapid, sustained strong thunderstorm development
accompanied by increasing severe weather potential, mainly in the
form of hail which could become sizable, appears possible overnight.
This could commence as early as 1-3 AM CDT, and a severe weather
watch may be needed.

DISCUSSION...Low-level flow is backing from westerly/southwesterly
to more of a southerly component and modestly strengthening across
the north central Gulf coast vicinity. This is allowing for
boundary-layer moisture return across the coastal plain from
southeastern Louisiana through southern Alabama, where deepening
convection has been evident along the low-level confluence zone near
the leading edge of this regime since prior to sunset. This is
occurring beneath steep lapse rates associated with daytime
boundary-layer heating and deep mixing, which occurred to the south
of a stalling frontal zone across northern portions of the Gulf
Coast states into the Great Plains.

Destabilization associated with the moistening recently became
sufficient to support short-lived thunderstorm development west of
Montgomery, AL. However, large-scale forcing for ascent remains
weak and, based on model forecast soundings, ongoing mid-level warm
advection may maintain substantial inhibition tending to suppress
sustained thunderstorm initiation for at least several more hours.

With time though, as mid/upper 60s F dew points begin to underrun
the northern periphery of the more strongly capping warmer air
aloft, initially scattered sustained thunderstorm development
appears increasingly probable. Once this occurs, intensification
may be rapid with mixed-layer CAPE forecast to increase in excess of
2000 J/kg. In the presence of strong deep-layer shear, beneath 50+
kt west-southwesterly 500 mb flow, the environment may become
conducive to supercells capable of producing sizable hail. While
low-level hodographs probably will remain modest to weak, stronger
storms may pose at least some risk for producing a tornado, in
addition to locally strong surface gusts.

Given the subtle nature of the mid/upper support, within flow that
may only very gradually transition from broadly anticyclonic to
cyclonic overnight, the timing of the more sustained, increasing
storm development remains unclear. Various model output has
suggested that this could commence as early as 06-08Z, but seems to
be trending toward a bit later overnight.

..Kerr/Thompson.. 03/26/2023

 

[MattPetrulli]

Extremely well written MD

 

[ARCC]

"Beware the westerly flow events in the SE."

Yep. Tomorrow evening is looking really interesting.

 

[KevinH]

This could potentially catch a lot of people off guard.
These extreme SE events are notorious for their surprise tornado outbreaks.

Yep

 

[Penitentes]

SPC ups tornado probs for today (Sunday) to 10% hatched. Mentioning possibility of "strong tornadoes."

"A seemingly potent thermodynamic/kinematic setup is shown by some models from LA east into AL. The favorable timing of the mid-level disturbance and an intensification of the 850-mb flow will conditionally yield a potentially very favorable corridor for intense supercells. Isolated to scattered thunderstorms will likely develop during the afternoon into the evening. Large to very large hail is possible with the stronger updrafts and several tornadoes are also possible, including a risk for a couple of strong tornadoes."

 

[buckeye05]

Looks like SPC is picking up on the same concerns. 10% hatched tornado risk has been added, with a mention of strong tornadoes possible.

Edit: ninja’d

 

[JBishopwx]

 

[Taylor Campbell]

We currently have a severe thunderstorm warning and newly issued severe thunderstorm watch. Looks like a rocky start to the day.

 

[Equus]

Has the feel of something escalating at the last minute if we get any sustained supercells in this environment, getting intrigued; may have some surprises

We don't even need super backed surface flow with westerlies that low in the profile, we have had some nasty events in similar setups so will be very much worth watching

 

[ARCC]

Very impressive soundings in south/central AL on the 6z HRRR later this evening.

 

[Matt Grantham]

Low-level flow is very unimpressive through the afternoon but does increase some in the evening. Numerous storms stuck on a west/east boundary with a tendency to cluster, may keep the tornado threat down. It's a very conditional low confidence threat.

 

[ARCC]

Nothing like elevated supercells at 4:30 to wake the kids…..

 

[Clancy]

Wicked train of storms this morning across Alabama. Dropping some big hail.

 

[ARCC]

Glad that core is going south of me.

 

[MoonBaby]

Had an alarm set to check the weather. Went from nothing to hail storm chaos right beneath me.