December 10th-11th, 2021 Outbreak

[StormNine]

There is a Level 2 out of 5 risk for West/Middle TN for Friday/Friday evening.  Details about low-level shear and storm mode remain but the potential is there for an active severe weather day with all hazards on the table. 

[memphishogfan]

[StormNine]

More about the severe weather potential.
The overall setup is that of concern.  We have a sub-1000 mb low tracking across where Missouri/Iowa/Illinois meet, which is actually a classic track for severe weather events for our region.  That will provide us suitable wind energy and wind shear.  It also appears that we will have an airmass that is unstable enough.
This does lead to a solid chance for severe storms Friday through Friday Night.  With that being said there are a few things to be decided.
- Will there be enough of a lifting mechanism out ahead of the front to create supercells.  If so then the severe weather threat and especially tornado threat jumps up quite a bit.
- What will the storm mode be ahead of the front.  A solid line will lead to more of a damaging wind event whereas a broken line will have the potential for embedded supercells aka a better tornado threat. 
- Will there be any messy convection out ahead of the system?  Which could limit the severe threat at least somewhat.
Still, we need to watch Friday afternoon through the wee-morning hours of Saturday as the ceiling for this event is fairly high

[Eric]

Source?

[andyhb]

Confidence has increased in a more favorable corridor for organized severe thunderstorms Friday night into early Saturday morning from roughly the vicinity of the MS River in eastern AR and northern MS northward into parts of the lower OH Valley. Across this region, the best overlap of sufficient instability, strong low-level and deep-layer shear, and a potentially favorable supercell mode may overlap for several hours (generally around 03-09Z). Have therefore increased severe wind and tornado probabilities across this region and have introduced and Enhanced Risk. Various forecast soundings from the 00Z NAM across this region show around 1000-1500 J/kg of MLCAPE, and effective SRH in excess of 300 m2/s2. This suggests some potential for nocturnal strong tornadoes.

Pretty discussion here in the newest D2 from SPC, which includes a rather large 10% hatched region for tornadoes, and generally aligns with my thoughts. Unfortunately, the timing of this has shifted towards more of a post-00z idea, where instability will still be sufficient and shear will be plenty for tornadic supercells.

I-40 corridor from Memphis to Jackson is of particular concern for those on this forum.

[StormNine]

Source?

I cited myself on my Facebook page. I had to give myself a high-five.

[Nash_LSU]

I-40 corridor from Memphis to Jackson is of particular concern for those on this forum.

The Jacksonish area of the state is just a tornado magnet, isn't it? They seem to get more than their fair share of strong tornadoes. 

[gcbama]

seems like the classic i-65 westward threat...almost always nocturnal threat as well, so dangerous

[schneitzeit]

The Jacksonish area of the state is just a tornado magnet, isn't it? They seem to get more than their fair share of strong tornadoes.

Yes it is. Our friend here will tell you that firsthand.

[schneitzeit]

OK guys, I need your advice:

Should I drive back into Middle TN Friday evening? Looks like I should be ok as long as I don't try to get back in the middle of the night. I'm coming from the northeast so I'll be ahead of it.

[Eric]

OK guys, I need your advice:

Should I drive back into Middle TN Friday evening? Looks like I should be ok as long as I don't try to get back in the middle of the night. I'm coming from the northeast so I'll be ahead of it.

12z HRRR has ETA of 1-3a for Mid TN, depending on locale.  If you make it in by midnight, you should be fine.

[Eric]

I cited myself on my Facebook page. I had to give myself a high-five.

Just wasn't sure if that was a NWS disco or some other posted discussion.  No worries.

[schneitzeit]

12z HRRR has ETA of 1-3a for Mid TN, depending on locale.  If you make it in by midnight, you should be fine.

Thanks. I'll play it by ear.

[Jilly]

NOAA Radio station WXK61 162.400 Cookeville is off air

[Eric]

SPC shifted the ENH eastward a smidge.