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Severe WX Severe Weather Threat 3/14-3/16

After lurking all week, I might as well jump in and ask. Tuscaloosa is under the bulls-eye, correct?

I've been a member here since long before 4/27/11. I just went back to the archived thread to see my posts from that day. My last one was about an hour before it passed within a mile of my house in Tuscaloosa. Someone mentioned recently about PTSD. For me, it's not the actual tornado that brought on years of awful memories. It was the days after. My house survived. Our church did not, but a team from Texas had a food truck and disaster assistance supplies ready to go early the 28th on the "slab" of our blown-away building. When the first truck and trailer needed able bodies to go into Alberta area, I jumped on. The days of assisting from trailers were humbling and horrifying. I'll never forget the spray-painted X's on houses, imploded houses with basements, center bathrooms left standing, "loot and I'll shoot" signs, radio voices that became lifelines, crying at the number of American Flags that sprouted over the rubble, curfews, and the level of desperation people suddenly experienced. Yet, across the bridge in Northport, it was business-as-usual. Very surreal.

I'm not ready for that again. But I'm sticking here for the duration. I don't understand a lot of the scientific stuff and I REALLY appreciate those who put things in laymen's terms. I can read a color map and see that my area of West AL is not looking good. So thank you all for your patience with the new people and the long-ago members like me who are back for more. Especially those who are not from AL but are sharing info for us in AL. It's a very welcome change from where I hang out for winter weather.
 
KevinH said:
@Fred Gossage and another MET have already spoken about this season so the feeling you have is warranted.
Click to expand...
To me, a primarily tropical cyclone tracker, just see all of the data we have is enough for me. But yeah.

We are now less than 24 hours out from the starting time of this event (tomorrow)
 
2,025 for 2025!

I can't believe I'm going to possibly get Severe T-storms in MARCH! That's usually a July thing.
 
UncleJuJu98 said:
15z rap is in range for Saturday afternoon. And it's bad like the nam and globals
Click to expand...

Grand Poo Bah said:
Extremely interesting you'd point this out because almost all the times the HRRR has gone off the charts with STP, it has coincided with "busts". I vividly remember being shocked when it got all the way up to 42 on May 6th 2024, and as we watched the event play out live, massive non tornadic supercells floated over the main area of concern and did nothing. I remember it almost felt eerie and I had a profound curiosity about what was holding them back. It wasn't until several hours later that tornadoes finally started dropping and Barnsdale was hit. That was the start of a 5 day outbreak that produced 185 tornadoes.

Same thing happened this year with the underperforming March 3rd system that had an HRRR STP of 15.
Click to expand...


High STP is a usually a necessary but not sufficient condition for tornado outbreaks.
In other words, you typically need to see a high STP being modeled for tornado outbreaks to occur, but it doesn't necessarily mean one will occur.

NAM seems to be the biggest offender as it often models high-capped environments with a high STP. HRRR tends to be more realistic and doesn't model the high capped areas with high STP as aggressively. I don't know if this is due to an underlying model architecture for producing higher STP values or if the HRRR is generally just less aggressive as a model.
 
D3 maintains mostly maintains MOD risk areas, MOD nudged futher north:
1741894593694.png
1741894579159.png

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
 
Not a fan, but good disco from Grams.
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
Click to expand...
 
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