Severe WX Severe Weather Threat Jan 12th, 2023

[UncleJuJu98]

For example March 25ths sounding vs Thursdays... Almost a spitting image.

 

[ashtonlemleywx]

Gary Lezak's LRC does long range forecasting based on cyclical patterns. He sells his model to subscribers on his substack blog.

It's basically a glorified modern farmer's almanac that is based on recent weather data and events.

 

[UncleJuJu98]

For example March 25ths sounding vs Thursdays... Almost a spitting image. View attachment 16591View attachment 16592

I fear we are going to be looking at a rather significant event upcoming Thursday. Just based of similar guidance from March 25th. I'll continue to look but it's glaring the potential for Thursday.

 

[UncleJuJu98]

Can't find many major differences really, your prototypical setup, nothing more to say , let's see how the minor details effect this event.

 

[ashtonlemleywx]

Something that I always pay close attention to with these winter setups is early morning convection and cloud cover. Seen so many of these setups get killed by not having enough dry air aloft and not enough clearing. Since the days are shorter than in the Spring, you have a much shorter window for diurnal heating and development of an elevated mixed layer. The timing literally has to be perfect.

 

[tennessee storm chaser]

Something that I always pay close attention to with these winter setups is early morning convection and cloud cover. Seen so many of these setups get killed by not having enough dry air aloft and not enough clearing. Since the days are shorter than in the Spring, you have a much shorter window for diurnal heating and development of an elevated mixed layer. The timing literally has to be perfect.

Most of winter time severe events are nocturnal anyways …

 

[KevinH]

I fear we are going to be looking at a rather significant event upcoming Thursday. Just based of similar guidance from March 25th. I'll continue to look but it's glaring the potential for Thursday.

I just realized this day was the EF4 Newnan, GA tornado

 

[UncleJuJu98]

Something that I always pay close attention to with these winter setups is early morning convection and cloud cover. Seen so many of these setups get killed by not having enough dry air aloft and not enough clearing. Since the days are shorter than in the Spring, you have a much shorter window for diurnal heating and development of an elevated mixed layer. The timing literally has to be perfect.

I think the dry air aloft forecasted is perfect for this winter time event like this, too much and it'll cause storms to not mature properly.

If you have a lot of dry air you'll need a lot of instability and steep lapse rates. The amount of dry air and cap we have in place Thursday is perfect for concise discreet convection along with the westerlies, directional sheer is on point.

It's all gotta mesh well or one thing will overpower the other.

 

[ashtonlemleywx]

Went ahead and drew a risk area for Jan 12th.

 

[KevinH]

View attachment 16594
Went ahead and drew a risk area for Jan 12th.

SAME areas… Not surprised

 

[UncleJuJu98]

Lol the 00z GFS is... odd, gunna post some stuff one second.

 

[UncleJuJu98]

Lol 00z GFS went all linear lol it broadened the low pressure system 850mb to the surface. Made winds almost completely southwesterly from the surface to 850mb.

00z GFS might be on some drugs. I'll toss lol

 

[UncleJuJu98]

Can't remember if it's the 00z GFS that usually is wonky. I've been told some model runs are not too reliable lol

 

[Clancy]

D 4-8 mentions severe threat around the 12th, but confidence too low to introduce area for now.

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 AM CST Sat Jan 07 2023

Valid 101200Z - 151200Z

...DISCUSSION...
An upper trough should progress quickly eastward across the
Southwest and southern Plains/Rockies from Day 4/Tuesday into Day
5/Wednesday, eventually evolving into a closed upper low by
Wednesday night. Low-level moisture will attempt to return northward
over parts of the southern Plains into the lower MS Valley and
Southeast ahead of this feature. However, prior frontal passages and
surface ridging over the central Gulf Coast region will likely slow
the inland advance of substantial low-level moisture, and act to
hinder destabilization.

Still, strong forcing for ascent should support convective
development Wednesday night into Day 6/Thursday from portions of
central/east TX/OK into the lower MS Valley and Mid-South as the
upper trough/low continues eastward. With ample deep-layer shear
forecast, some of these thunderstorms could be strong to severe. The
main limiting factor for a more substantial threat for organized
severe thunderstorms is weak forecast instability, which is
correlated to the incomplete low-level moisture return. Regardless,
trends in deterministic and ensemble guidance will be monitored for
possible future inclusion of a 15% delineation across parts of these
regions from late Wednesday through Day 7/Friday. But, at this point
the overall severe threat appears too isolated/marginal to introduce
any areas.

..Gleason.. 01/07/2023

 

[UncleJuJu98]

Timing has sped up on both euro and GFS, same general consensus on discreet convection but les veering of winds with height from the surface up, indicates lesser of a tornado threat , kindve suspicious of this I'm going to look at another event I think it was Easter 2020 with a broader low as the GFS and euro are starting to forecast and see what happens with that one

 

[UncleJuJu98]

You'd rather have the surface low in about Arkansas instead of it directly north of your location for better veering, if the system slows down and allows the shortwave to round the base more you'll be back on track with previous thinking of yesterday morning and afternoon. Just as easily could change back thankfully we have the Nam starting to come in range that'll help give more clarity to wether models are flip flopping or not.

 

[UncleJuJu98]

12z nam is running slower than the globals, also digs the trough a bit more.

06z euro vs 12z nam.

 

[Clancy]

This morning's AFDs from BMX, JAN and FFC indicate some broad model agreement but highlight significant uncertainty about wind profiles, moisture return and timing. Also, CIPS analog-based probabilities still showing a highlighted corridor for the 12th. Below are analogs for this time frame pulled from Central Alabama.

1. 19991115/0000

2. 20051220/0000

3. 20071216/0000

4. 20101220/0000

5. 19920211/0000

 

[UncleJuJu98]

12Z GFS Is back on board with it's volatile setup, delay the shortwave about 6 hours and you'll be peak heating.

 

[UncleJuJu98]

Still teetering on a bigger wind damaging wind setup than tornado, this events gunna come down to the mesoscale models.