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Possible Severe Weather April 22nd-23rd

Charleston WFO had some strong wording as well in their discussion. Unlikely rain cooled wedging will save the region this go around with SigTor parameters around 8 to 10?

Thursday and Thursday night: The main concern across the short term
is the severe weather potential Thursday afternoon/night. There is
good model consensus that a deepening area of low pressure will move
eastward toward the Ohio Valley during the day and drive a strong
cold front across the Deep South. The near storm environment has the
potential to be quite impressive with strengthening deep layer shear
and diurnal heating leading to increasing surface based instability.
Also of note, mid-level lapse rates steepen significantly through
the afternoon and evening. A perusal of model soundings shows nicely
veered wind profiles with SRH values surging to in excess of 300
m2/s2, and Significant Tornado Parameter values upwards of 8-10.
Suffice to say, a potentially impressive environment capable of
producing numerous supercells with damaging wind gusts, large hail,
and a few strong tornadoes. Timing remains the most difficult aspect
to nail down given model spread. The GFS seems to be the fastest,
bringing the severe threat through in the early to mid afternoon
hours. The NAM appears to be the slowest and perhaps most dire, with
stronger severe parameters and a timing that favors the late
afternoon and evening hours. So we will continue to highlight the
severe potential and the timing uncertainty. We also expect another
round of widespread significant rainfall, so at least minor flooding
could become an issue given intense rainfall rates and wet
antecedent conditions. Conditions should start to improve by late
in the overnight as the front moves offshore.
 
There it is, broken line of supercells embedded in a QLCS in AL/GA/SC/NC coinciding with high parameters 3052D123-3068-4E2D-8F7C-7D21B2F28CC2.pngB934D52E-3BE0-494E-8A77-B5F4E5EC82B1.png
Sounding near CLT 8D70B0A3-FEEB-43E8-8D66-76C7F44AA850.pngsounding near ATL9E4CFA22-F10C-4A4F-BCFC-D4A5CCB7066B.png
These hodograph shapes are what concern me, I’ve seen Cameron nixon mention of it but a little bit of backing around 3km has actually been noted with violent tornado events
Although that is a lot of backing, so idk
 
Nam shows it more toward Thursday AM here. Looking rougher as it goes east. Doesn't seem to loose any push. Just keeps walking east.

1587501061161.png
 
BufordWX said:
This is the HRRRv4 18z at hour 48 so take it FWIW, but it shows an awful lot of action on the gulf coast. That is something that could help those to the north.View attachment 40024
Click to expand...
Yep, coast stealing the energy for sure, happens 95% of the time. Brad Nitz was talking about this a few minutes ago. I would lean this way as of now since it always happens.
 
Myfrotho704_ said:
There it is, broken line of supercells embedded in a QLCS in AL/GA/SC/NC coinciding with high parameters View attachment 40028View attachment 40029
Sounding near CLT View attachment 40032sounding near ATLView attachment 40031
These hodograph shapes are what concern me, I’ve seen Cameron nixon mention of it but a little bit of backing around 3km has actually been noted with violent tornado events
Although that is a lot of backing, so idk
Click to expand...

Would there be a reason to trust this over the higher-resolution 3k nam, which seems like it's being much nicer to upstate SC and NC?
 
So local weather stations in ATL are saying more of an early morning event but im reading from spc more of an afternoon event?
 
mbway091 said:
Would there be a reason to trust this over the higher-resolution 3k nam, which seems like it's being much nicer to upstate SC and NC?
Click to expand...
It is the Lr hi res NAM but is does look like the HRRRV4, but it took a jump north with the pseudo warm front
 
Area Forecast Discussion
National Weather Service Peachtree City GA
340 PM EDT Tue Apr 21 2020


...Afternoon Area Forecast Discussion...


.SHORT TERM /Tonight through Wednesday Night/...

Remnants of a weak frontal boundary/trough continue to move south
across the CWA this afternoon. No precip is associated with this
boundary, just some clouds. Dry conditions will persist through
tomorrow afternoon. Moisture will begin to return late tomorrow
ahead of the next weather-maker. The best chances for precip will be
along and north of the warm front late Wednesday night/very early
Thursday. Some locally heavy rainfall will be possible towards
12Z.

NListemaa


.LONG TERM /Thursday through Tuesday/...

An Enhanced Risk is in effect for the Day 3 Severe Thunderstorm
Outlook valid for Thursday as a rapidly intensifying low-pressure
system sweeps... once again... across the Southeast. Deja vu,
much? Currently there a quiet a few unknowns to the system that
are still coming together. The first of which is timing. Several
synoptic scale models are beginning to come together with the
timing of the upper-level shortwave, which at its extreme, are out
of phase by about 12 hours with the GFS being the fastest and the
Canadian being the slowest. The timing of this wave will answer a
lot of questions with the overall organization of the storm
system. For instance, if we`re expecting one stronger wave in the
afternoon or two waves of severe weather in the morning/early
afternoon and again in the evening. However, solutions are
leaning towards two waves versus just one. The second major
unknown will be the placement of the baroclinic boundaries, in
particular a warm front which will be the catalyst for tornadic
supercells through the morning and early afternoon through the
forecast area. Where this boundary sets up and is able and advect
to will determine the coverage of possible tornados in the area
and the extend of potential strong wind gusts. These variables
will help shape the initiation and evolution of severe
thunderstorms throughout the day.

So what DO we know? Severe parameters for discrete supercellular
convection will be in place and abundant sometime through the day
and evening on Thursday. Instability will be higher than in
several of our past severe weather days this year. MUCAPE values
at projected to be up to 2000-3000 J/kg, with similar SBCAPE
values in the warm sector. Low level shear will also be abundant
with 0-6km Bulk shear between 50-70 knts and low-level 0-1 km
storm relative helicity values well over 300m2/s2. the combination
of these values with minimal if any CIN is projecting EHI and
SigTor values over 4 for several areas of central Georgia.
Furthermore, modeled hodographs look very favorable for rotating
tornadic supercells with nearly all the horizontal vorticity being
streamwise versus crosswise making storms efficient in turning
environmental shear into rotating storms. With all this combined
threats for large hail, damaging wind gust, and tornadoes all
look possible, with a few tornadoes having the potential to be
long- track, strong tornadoes. Furthermore, with several rounds of
heavy rain possible with the storms and central Georgia being
saturated from previous rains, flash flooding will also be a
concern with an areal average of 1.5 to 2.5 inches forecast and
higher local values likely where stronger storms develop for
prolonged periods of time.
 
Myfrotho704_ said:
It is the Lr hi res NAM but is does look like the HRRRV4, but it took a jump north with the pseudo warm front
Click to expand...

Unless I read it wrong at no point does the 3knam even give me a severe sounding whereas the 12k gives me a tornado sounding as the broken line moves through in the dark in the night yay.
 
Would favor a MCS rn along the gulf coast kinda reducing the threat up north, similar to that moderate risk bust around the OH valley back earlier this year, NWP love to underestimate the extent of stratiform precip and the hrrrv4 seems to catch on to it
 
Shaggy said:
Unless I read it wrong at no point does the 3knam even give me a severe sounding whereas the 12k gives me a tornado sounding as the broken line moves through in the dark in the night yay.
Click to expand...
It’s amazing how poorly NWP have done with these next 2 threats
 
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