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Severe WX Severe threat 3/30-3/31

Just to piggyback off of what @JPWX said, cloud cover and morning/pre event showers are something that has to be resolved with every outbreak. Even at this range, we probably won’t know until the day of how those will shake out.

I will say, cloud cover isn’t necessarily fatal to an outbreak. It can help break the CAP or increase instability, but there are a 1000 ways to skin a cat.
 
Here's my main issue especially with capping issues and the ongoing convection that SPC is hinting at in Day 2 discussion.

12z and 6z 3km NAM valid at 4am Sunday. The issue I have with this is if you do have capping issues, then why is the 3km NAM showing convection at 4am Sunday morning? Here's the 12z HRRR valid at 4am Sunday showing nothing except along Gulf Coast.
 

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Another thing, in looking at the general environment on Sunday in the Southeast, is the possibility for a few surprise storms during the afternoon. A pulse/multicellular mode is evident during the afternoon hours across Alabama and Georgia. While they won't be organized, with a broad regime of moderate instability in place, any storm that taps into elevated kinematics could end up producing some hail, downbursts and maybe even a spin-up. This is reflected in FFC's AFD for the period. So, not a huge risk, but something to keep in mind.
More widespread showers and thunderstorms develop across the CWA
as the stronger trough, currently out west, moves to our north
overnight Saturday. Greater southerly flow, moisture availability,
and diurnal heating will mean increased coverage in thunderstorms
as well. Mean CAPE values currently sit closer to 1000 J/Kg
Sunday afternoon. Strengthening low level winds may be able to
elongate hodographs far enough ahead of the incoming cold front to
get storms turning. Will need to keep a close eye on storms in
the warm sector, particularly in central GA. The main hazards
would be damaging winds and even an isolated tornado. Limited mid
and low level lapse rates suggest a more limited hail threat.
PWATs in the warm sector of over 1.5" also suggest the potential
for efficient rain makers and locally heavy rainfall.
Click to expand...
12Z-20250329_HRRRSE_prec_radar-24-36-30-100.gif
 
So I haven't forgotten about you all and my model run...my model actually caused my computer to crash after running straight for about 16 hours LOL (I think my computer just got too hot, I didn't have it ventilated well enough).

But before it crashed, I did snag some interesting Updraft Helicity images. These are not "swaths", they are instantaneous snapshots. Remember this is 1 km resolution, so each point is about 0.6 miles wide.

1743267329357.png

1743267353146.png

1743267372856.png

1743267399604.png

Definitely shows potential for some tornadoes in the Memphis area. It's perhaps "zoomed in" a bit too far, so I'll run a new model later today that is zoomed out more at a lower resolution.
 
S
wx_guy said:
So I haven't forgotten about you all and my model run...my model actually caused my computer to crash after running straight for about 16 hours LOL (I think my computer just got too hot, I didn't have it ventilated well enough).

But before it crashed, I did snag some interesting Updraft Helicity images. These are not "swaths", they are instantaneous snapshots. Remember this is 1 km resolution, so each point is about 0.6 miles wide.

View attachment 37642

View attachment 37643

View attachment 37644

View attachment 37645

Definitely shows potential for some tornadoes in the Memphis area. It's perhaps "zoomed in" a bit too far, so I'll run a new model later today that is zoomed out more at a lower resolution.
Click to expand...
Sorry for the crash and thanks
 
No upgrade yet for Sunday, but this did catch my eye:
Scattered, initially discrete supercells are expected to develop
from the confluence of the OH/MS rivers southwestward into the
Texarkana region Sunday afternoon along the cold front and dryline.
Strong flow associated with the intensifying cyclone will promote
elongated hodographs featuring nearly uni-directional wind profiles
and effective bulk shear values on the order of 50-60 knots. This
will promote splitting supercells with the potential for large to
very large (2+ inch) hail. A more appreciable supercellular tornado
threat may emerge through early evening across the lower OH
Valley/mid-MS Valley where stronger veering in the lowest 1-2 km is
anticipated amid weak pre-frontal isentropic ascent between 925-850
mb. While the tornado threat may be maximized through this corridor,
low confidence in storm mode (due to the potential for splitting
cells/destructive interactions) limits confidence in this potential
to warrant higher probabilities at this time.

However, upscale growth is anticipated through mid/late evening as
the secondary upper disturbance migrates into the Texarkana region.
Consolidation of multiple clusters into one or more organized linear
segments is expected as storms push east towards the MS Valley with
a gradual increase in the potential for damaging/severe winds.
Additionally, low-level shear will remain favorable for embedded
mesovorticies as the line pushes into western TN/northern
MS/northwest AL through the overnight hours.
 
No MDT and likely not deserved. I think we will see a few strong events, but it looks like this thing gets linear faster than the global models originally anticipated and the strong tornado and hail threat appear to have diminished substantially (outside of ARKLATEX/MO).

Is it just me or do almost all global models move too quickly and the regionals slow everything down? Seems like the last few events have moved further and further west or the right dynamics appeared too late to reach the peak intensities originally forecast? Just something I THINK I’ve noticed but I could be nieve.
 
JPWX said:
No upgrade yet for Sunday, but this did catch my eye:
Scattered, initially discrete supercells are expected to develop
from the confluence of the OH/MS rivers southwestward into the
Texarkana region Sunday afternoon along the cold front and dryline.
Strong flow associated with the intensifying cyclone will promote
elongated hodographs featuring nearly uni-directional wind profiles
and effective bulk shear values on the order of 50-60 knots. This
will promote splitting supercells with the potential for large to
very large (2+ inch) hail. A more appreciable supercellular tornado
threat may emerge through early evening across the lower OH
Valley/mid-MS Valley where stronger veering in the lowest 1-2 km is
anticipated amid weak pre-frontal isentropic ascent between 925-850
mb. While the tornado threat may be maximized through this corridor,
low confidence in storm mode (due to the potential for splitting
cells/destructive interactions) limits confidence in this potential
to warrant higher probabilities at this time.

However, upscale growth is anticipated through mid/late evening as
the secondary upper disturbance migrates into the Texarkana region.
Consolidation of multiple clusters into one or more organized linear
segments is expected as storms push east towards the MS Valley with
a gradual increase in the potential for damaging/severe winds.
Additionally, low-level shear will remain favorable for embedded
mesovorticies as the line pushes into western TN/northern
MS/northwest AL through the overnight hours.
Click to expand...
Splitting cells/destructive interactions..
 
I would argue the way SPC words what I posted above this still warrants a Moderate Risk especially West Tennessee, Arkansas, and North MS area.
 
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