December 12-14, 2022 | Significant Tornado Outbreak

[ClicheVortex2014]

A trough will develop over the west later this week, soon to become a rather large trough. As of right now, GFS and Euro stall out a front from a previous system north of the Gulf coast, which is favorable for getting anomalous moisture in the warm sector. Right now it looks like a severe threat may materialize Monday and/or Tuesday next week for Texas and perhaps Dixie Alley.

Edited December 14, 2022 by ClicheVortex2014

[ClicheVortex2014]

Big difference in wind profile compared to the last event, but still a noteworthy setup.

 

An example of a sounding in east Texas. Wind profile looks more typical of May or so.

Edited December 6, 2022 by ClicheVortex2014

[Iceresistance]

SPC has a slight risk for D7 for Texas, Oklahoma, Louisiana, Arkansas, and Missouri. 

Edited December 6, 2022 by Iceresistance

[Ingyball]

There's some real potential with this trough, however I think the GEFS is too progressive with how it kicks out. This pattern favors slow and more amplified so I wouldn't be surprised to see west trends over time. 

[ElectricStorm]

12/12 has my attention 🤔

It'll be interesting to see how this plays out, wondering if we'll see a west shift. 

[snowlover2]

8 hours ago, Iceresistance said:

SPC has a slight risk for D7 for Texas, Oklahoma, Louisiana, Arkansas, and Missouri. 

Quote

 Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0359 AM CST Tue Dec 06 2022

   Valid 091200Z - 141200Z

   ...DISCUSSION...
   Medium-range models over the past two runs have converged with
   respect to depiction of the large-scale features -- both surface and
   aloft -- through all but the very end of the period (Day 8/Tuesday
   Dec. 13).  

   At this time, severe-weather risk appears low through Day 6, as a
   relatively low-amplitude pattern early in the period gradually
   amplifies, as large-scale troughing slowly evolves over the West.  

   It appears at this time that the result of Gulf of Alaska short-wave
   troughing digging southward in broadly cyclonic western NOAM flow on
   Day 5/Saturday, will be deepening of the longer-wave trough, and
   eventual eastern advance of the trough across the Intermountain West
   Day 6/Sunday.  During this time, downstream convective potential
   appears likely to remain subdued in weakly anticyclonic flow east of
   the Rockies.

   Day 7, models suggest that the trough begins emerging into the
   Plains.  As this occurs, surface cyclogenesis is expected to begin
   over the central/southern High Plains vicinity, and then move across
   roughly the Kansas vicinity during the evening.  As this low
   advances, strengthening southerly low-level flow would advect
   seasonably high theta-e air northward into the evolving warm sector,
   suggesting ample destabilization to support storm development as a
   cold front sweeps across the southern Plains.  Meanwhile, with the
   low-level southerlies topped by strong southwesterly flow
   accompanying the upper system, shear profiles consistent with
   supercell storms are indicated.

   Given this potential for severe weather indicated by both the GFS
   and ECMWF, and with at least reasonable support for such evolution
   evident within both ECMWF and GEFS ensembles, a 15% risk area is
   being introduced for Day 7 -- centered over the Arklatex region.

   Some risk could continue into Day 8, across the Tennessee and
   Mid/Lower Mississippi Valleys, but this remains a bit more uncertain
   at this time.

   ..Goss.. 12/06/2022

 

 

[ClicheVortex2014]

The warm sector on GFS is a ridiculous outlier compared to Euro and Canadian. Massive warm sector on GFS.

[Neoncyclone]

Phewwww

 

[ClicheVortex2014]

4 hours ago, ClicheVortex2014 said:

The warm sector on GFS is a ridiculous outlier compared to Euro and Canadian. Massive warm sector on GFS.

Had to wait to get home to post this but I found where GFS strays from the others.

Hour 96... cold front from previous system is transitioning from stationary front to warm front. No dramatic differences. Maybe a little more disagreement than there should be at this range. Looking away from the greens, you can see which one is going to have the larger warm sector if you pay attention.

 

Hour 132. Here's where GFS really goes off in another direction. GDPS and Euro have a reinforcing push of cold air while GFS has the opposite. This is why GFS has a severe event for most of the southern half of the Plains... a huge area for this time of year. That's a big red flag.

Side note... as Ingyball was saying, GFS is starting to trend slower with the trough. GFS has a dryline just outside of my CWA before everything pushes east.

Edited December 7, 2022 by ClicheVortex2014

[Sentinel]

1 hour ago, ClicheVortex2014 said:

Had to wait to get home to post this but I found where GFS strays from the others.

Hour 96... cold front from previous system is transitioning from stationary front to warm front. No dramatic differences. Maybe a little more disagreement than there should be at this range. Looking away from the greens, you can see which one is going to have the larger warm sector if you pay attention.

 

Hour 132. Here's where GFS really goes off in another direction. GDPS and Euro have a reinforcing push of cold air while GFS has the opposite. This is why GFS has a severe event for most of the southern half of the Plains... a huge area for this time of year. That's a big red flag.

Side note... as Ingyball was saying, GFS is starting to trend slower with the trough. GFS has a dryline just outside of my CWA before everything pushes east.

I feel as if I spy a JAX rule...

[StormfanaticInd]

I think the models are way too warm with this storm. That blocking will be heard from

[Iceresistance]

SPC now has a broad Slight Risk for Tueaday, 12/13. 

 

The Slight risk for Monday, 12/12, is even further west. 

[Iceresistance]

 

[ClicheVortex2014]

23 hours ago, ClicheVortex2014 said:

Had to wait to get home to post this but I found where GFS strays from the others.

Hour 96... cold front from previous system is transitioning from stationary front to warm front. No dramatic differences. Maybe a little more disagreement than there should be at this range. Looking away from the greens, you can see which one is going to have the larger warm sector if you pay attention.

 

Hour 132. Here's where GFS really goes off in another direction. GDPS and Euro have a reinforcing push of cold air while GFS has the opposite. This is why GFS has a severe event for most of the southern half of the Plains... a huge area for this time of year. That's a big red flag.

Side note... as Ingyball was saying, GFS is starting to trend slower with the trough. GFS has a dryline just outside of my CWA before everything pushes east.

Unfortunately, it looks like Euro and GDPS caved to GFS. Cold front doesn’t even make it as far south as Mobile, AL before stalling out and eventually moving north. 
 

Pooling moisture south of a stationary front that’s this far north in the cool season is usually bad news. Add a strong, dynamic system on top and it’s even worse. 
 

Thankfully GFS’s warm sector isn’t nearly as big as yesterday. It still spans from eastern Texas into all of Louisiana and Arkansas before shrinking into western Tennessee and Mississippi. Still a sizable warm sector for December.

[Chinook]

wow, Day 6 and Day 7 have a 15% outlook. I wasn't looking at the models too closely, but yes, obviously a large amplitude trough coming up.

[ClicheVortex2014]

On 12/5/2022 at 10:35 PM, ClicheVortex2014 said:

Big difference in wind profile compared to the last event, but still a noteworthy setup.

 

An example of a sounding in east Texas. Wind profile looks more typical of May or so.

Hodographs are looking longer

[Iceresistance]

@CentralLA_Wx D6 Enhanced for your area on the SPC. 

[Iceresistance]

D5

D6

[Neoncyclone]

Phew, I do recall saying that I thought this years second season would overperform, but wow another potentially significant severe event in December.

[Iceresistance]

What is with the 12z GFS having the severe storm potential in Western Oklahoma for Monday (12/12)?

[ElectricStorm]

Wow, a Day 6 enhanced is about as far out as you'll see an enhanced, definitely not a good sign. 

What concerns me for Monday is the fact it could be a significant nocturnal event, which are obviously dangerous. This kind of feels like the lead up to 10/10/21 where the threat area started further east but shifted west as we got closer. I don't see this being a moderate risk day like 10/10 was but I think it still has potential, even though most people will probably be focusing more on Tues.

[ClicheVortex2014]

Parameters aren't high-end yet, but the pieces are there.

Don't think we'll have to worry about low-level lapse rates with this event. Not much directional shear in the 0-1.5km layer though. 

Strong deep-layer shear means there's a good likelihood for long-lived supercells if storm mode allows. This is in east Texas.

[ClicheVortex2014]

Assuming the day 6 enhanced moves into day 5, the last 5 day 5 enhanced risks have happened in the cool season.

The day 5 enhanced we saw in November was the first one issued in November since they began issuing enhanced in days 4-8. Again, assuming we see a day 5 enhanced in the next update, we'll see the first day 5 enhanced ever issued in December. 

 

Since we have a day 6 enhanced...

 

Edited December 9, 2022 by ClicheVortex2014

[ClicheVortex2014]

GFS is slowly ramping up the parameters associated with STP

E TX

[ClicheVortex2014]

That Texas panhandle dryslot, man