11/29/22 MDT Outlook Issued -- Regional outbreak possible.

[rnj79]

I am in Baton Rouge.

Was there any shifts/expansions in the risk area with the 7am update?

[Quincy]

28 minutes ago, rnj79 said:

I am in Baton Rouge.

Was there any shifts/expansions in the risk area with the 7am update?

The slight, enhanced and moderate risk areas were essentially unchanged. The marginal risk was expanded slightly farther west across East Texas. 

[nwohweather]

8 hours ago, CryHavoc said:

"a long tracked and intense tornado may occur'

Now saying this... "Multiple rounds of severe thunderstorms -- some capable of long-tracked tornadoes with EF3+ damage potential -- will be possible this afternoon into tonight over parts of the lower Mississippi Valley region and Mid-South."

Two things that really stick out to me is the lapse rates (pretty high for the mid South) and very high SRH. You're going to see some strong updrafts over there today with quick storm motions, just a perfect combo for long track tornadoes. 

[Radtechwxman]

14z hrrr is a potent run. Trio of long track supercells emerging out of ne LA into central MS with some intense, long helicity tracks.

[Quincy]

Several factors seem to point toward higher-end potential today across the region. Many have been discussed above. 

Lapse rates: 15z mesoanalysis shows mid-level lapse rates of 7-7.5 C/km across much of Louisiana and western Mississippi. A broad area of >8 C/km exists over East Texas. Typically these events “underperform” in terms of hail production in the Mississippi Valley, but you could see quite a bit of hail, especially across LA/AR/E TX.

Instability: Thanks in part to steep lapse rates aloft, instability profiles also appear to become uncharacteristically large for such a cool season event. Also, rich low-level moisture is rapidly being transported north and east. Note lower 70s dew points already in place from SE TX into S LA. This is supporting enlarged low-level CAPE, which is a key variable with respect to significant tornado events. 

Shear: Both deep layer and low-level shear will easily be supportive of severe/sig severe. Also note a more westerly component to the upper level flow than we tend to have in place. WSW/SW, as opposed to the SSW flow we often see when big troughs trigger moderate risk events in the region.

More thoughts on the upper level support… We see a broad trough impinging on the area. This is allowing the steeper lapse rate plume to overspread moist low levels. Too often we see a barreling trough with a messy QLCS mode. While convective evolution could still get messy, the shear vectors do favor discrete or at least semi discrete modes for several hours.

A few limiting factors: Despite a more westerly than southerly component to the upper level flow, deep shear vectors are still fairly parallel to the initiating warm conveyor belt (SW to NE). This could result in bands and clusters of supercells, full of mergers and other storm interactions. Still, backing of wind fields is creating sickle-shaped low-level hodographs, in addition to elongated deep layer hodographs. Finally, low-level lapse rates will probably remain fairly marginal for a while. This may cap the ceiling a bit, particularly early in the event. 

The threat should really ramp up late this afternoon and, unfortunately, continue into the evening hours with eastward extent across Mississippi.

Hopefully awareness is there and impact to life and property is minimized. 

[ICEHOCEY77]

Latest SPC update: 

Consideration was made to introduce a
   small HIGH risk, but still too much uncertainty in the exact
   corridor of highest risk since moisture is not yet in place and
   there is no surface boundary to focus on.

[Radtechwxman]

Pretty much sounds like they will go high at some point. Parameters def support it. Storm mode is my main concern but like Quincy said, the hodos will support at least semi-discrete supercells even if shear vectors aren't completely perpendicular to initiating waa regime. 

[stormdragonwx]

Yeah saw that coming.

[nwohweather]

26 minutes ago, ICEHOCEY77 said:

Latest SPC update: 

Consideration was made to introduce a
   small HIGH risk, but still too much uncertainty in the exact
   corridor of highest risk since moisture is not yet in place and
   there is no surface boundary to focus on.

First one in 20 months if it happens

[DanLarsen34]

This is worth noting.

.

[nwohweather]

14 minutes ago, DanLarsen34 said:

This is worth noting.

 

 

.

 

 

Jesus, essentially a 4/27/11 redux on that model, just a state to the left

[MUWX]

PDS watch coming per latest MD. Sure seems like they are going to go high risk next update. 

[stormdragonwx]

26 minutes ago, DanLarsen34 said:

This is worth noting.

 

 

.

Interesting. Makes me wonder if they might nudge the mod risk area further west if that 2nd wave of supercells at sunset in AR/LA verifies.

[olafminesaw]

Already a nasty looking warned cell in central Louisiana

[DanLarsen34]

.

[Quincy]

18z SHV (Shreveport) sounding sampled 8.4 C/km mid-level lapse rates. Not only high end, but exceeds the observed maximum for late November:

 

[Normandy]

Following this now.  Look forward to the updates and stay safe to those in the affected regions.

[kayman]

22 hours ago, METALSTORM said:

The SE forum is mostly comprised of people in the Carolinas. They'll closely follow a 384hr model predicting a trace of snow in the Piedmont but they have 0 interest in severe. Kind of the same with TN Valley. Just how they are. 

 

On 11/28/2022 at 2:50 PM, southmdwatcher said:

This event looks like there could be some significant tornadoes. On another note, severe outbreaks that crossover to multiple regional subforums, have had difficulties.  In the older forum, the Central/Western states took it upon themselves to have threads for any event west of the Appalachians. 

Hey I'm a frequent in the SE forum.  I'm a survivor of the 04/27/2011 super outbreak and follow severe weather closely. If Possible, I'll take it upon myself up create a thread for today's regional severe weather event is need be to update those in the forum. I'll even link it here for you all to cross post. (edited due to autocorrect errors) 

[buckeyefan1]

29 minutes ago, kayman said:

 

Hey I'm a frequent in the SE forum.  I'm a survivor of the 04/27/2011 super outbreak and follow severe weather closely. If it take it upon myself up create a thread for today's regional severe weather event is need be to update those in the forum. I'll event link it here for you all to cross post. 

The SE crew is interested in severe weather and appreciates when threads for risk areas are posted. I try to make sure they are pinned if needed as well. 

[stormdragonwx]

20z update is out. They didn't pull the trigger on the high risk. https://www.spc.noaa.gov/products/outlook/day1otlk.html

[nwohweather]

If the storm mode could clean up a bit today could get really dicey, they all have that look for sure but no clean inflow at this time. Watching the one south of Jackson closely

[Santa Clause]

Messy storm mode so far.

[eyewall]

Chasers are running out of daylight to get anything

[Santa Clause]

Sunset chase

[stormdragonwx]

6 minutes ago, eyewall said:

Chasers are running out of daylight to get anything

That was one of the reasons why I decided to hold off on going out. Fast storm motions, lots of trees, and limited daylight for when the storms would likely go tornadic was less than ideal to make the chase worthwhile. I have dodged a fast moving wedge at twilight out there and its not something I care to repeat.

[DanLarsen34]

Storm approaching Bassfield is starting to ramp up significantly.


.

[Calderon]

The supercell near Wisner, LA is going to be a problem for the Jackson area in time. It's got a lot of space outside of the thunderstorm over Waterproof, LA. 

[stormdragonwx]

Yazoo City and Eden, MS might be getting one momentarily. Nice couplet on the storm passing thru.

[Chinook]

49 minutes ago, DanLarsen34 said:

Storm approaching Bassfield is starting to ramp up significantly.


.

confirmed tornado as of about 6:05 or 6:10 eastern time, Bassfield

[Ed, snow and hurricane fan]

49 minutes ago, DanLarsen34 said:

Storm approaching Bassfield is starting to ramp up significantly.


.

Ryan Hall is showing a correlation coefficient near Bassfield and heading towards I-59 between Hattiesburg and Laurel