January 28-30 Severe threat. S Plains to TN valley to SE

[MichelleH]

The 12Z NAM has already shifted a bit closer to the GFS in that it shows somewhat greater phasing with the trough a day before the (likely) outbreak. There are already hints by 00Z on 01/30 that the NAM attempts to develop the secondary surface low which is well-established on the GFS ensembles and even the recent ECMWF. This trend was not apparent so early on previous NAM runs, so most likely it is depicting a somewhat deeper evolution of the low with greater backing of the low-level wind field this run. Of course, I expect the trend in the NAM to be gradual so that it will not have a complete grasp of the synoptics and thermodynamics until about a day before the actual event. At that range, the NAM should be much more useful with which to make an informed judgment re: convective mode, but at this point all the trends are moving toward more discrete and semi-discrete activity with a significant outbreak very likely.

Edit: The 12Z NAM now strongly backs the low-level winds by 00Z 01/30 relative to the 00Z run...which showed veering winds over the MS Valley in the same time frame--a rather significant and certainly drastic shift. Most amazingly, it brings near-60°F dew points a bit farther north than on the 00Z run...this time extending a bit north of KIKK and closer to KFWA. This means that a substantial severe threat would shift a good 40-60 mi farther north than on the 00Z run and even start to bring the Chicago outskirts into play with backed winds now near the lakefront. It also brings 60°F+ dew points as far north as beyond PAH early on 01/30 and actually suggests a nocturnal outbreak overnight 01/29-01/30 over E AR, N MS, NW AL, a fair chunk of W TN, and SW KY. This would put the Memphis area almost in the center, much as on 02/05/2008. Moreover, the NAM keeps backed winds from 00Z 01/30 throughout almost the entire day with very little mixing of the dew points due to the 850-mb vector relative to the front. For this time of year, this is as impressive as I have ever seen in all except a few, top-end winter outbreaks like Super Tuesday or 01/24/1999. The NAM suggests the significant TOR threat would extend as far east as NE AL, NW GA, E-C TN, and S-C KY early morning 01/30 (with 80+ kt 850-mb SSW jet!) and then into the Carolinas by afternoon-overnight with 60°F+ dew points as far north as DCA. The run is absolutely scary with eye-popping soundings across such a wide area and much higher instability and 0-2-km SRH than on previous runs. If this were to verify, a potentially record-breaking winter outbreak on a par with Super Tuesday or even the Enigma outbreak would be a very real possibility, which I am now beginning to contemplate.

Do you think North Central Alabama has a significant tornado threat with this system? You mentioned NW AL and NE AL, so I was just wondering. Thanks!

[Ground Scouring]

Do you think North Central Alabama has a significant tornado threat with this system? You mentioned NW AL and NE AL, so I was just wondering. Thanks!

Basically and definitely, yes, as I divided north AL into NE and NW sections. They both meet in N-Central AL, so the answer is in the affirmative.

[gusfront]

JoMo or anyone else in the thread is this looking like a substantial tor threat or even a strong tor type threat for the sekan , neok and swmo areas especially the kjln ( joplin mo ) areas monday night and tuesday time frame..?????

[JoMo]

JoMo or anyone else in the thread is this looking like a substantial tor threat or even a strong tor type threat for the sekan , neok and swmo areas especially the kjln ( joplin mo ) areas monday night and tuesday time frame..?????

 

Looking at the 12z NAM/GFS, it looks like our best chance for storms will be Tues morning. Instability isn't all that great but shear is pretty abundant. GFS/NAM are veering our winds to the SW by early afternoon. At this point the worst looks to be east of us, however.. if the system slows down or strengthens faster, we may be in worse shape.

 

Springfield sure is hitting the "All Modes" of severe pretty hard eh?

[tornadotony]

Usually means S to SE winds at the surface. 

The process of backing refers to the counterclockwise turning of the wind, either spatially through a depth or temporally.  Winds can back, say from S to SE for example, on one surface or through a layer in time, often with the approach of a strengthening low pressure system.  Winds can also back with height at one given time, indicative of cold air advection, usually found behind a cold front.

[Ground Scouring]

Looking at the 12z NAM/GFS, it looks like our best chance for storms will be Tues morning. Instability isn't all that great but shear is pretty abundant. GFS/NAM are veering our winds to the SW by early afternoon. At this point the worst looks to be east of us, however... if the system slows down or strengthens faster, we may be in worse shape.

The GFS, the ECMWF, and the NAM have been trending slower with the low for some model cycles. Still, I think that Joplin will be NW of the greatest instability but would likely be in the zone for isolated tornadoes, possibly even a strong one, given the wind fields.

By the way, the 12Z ECMWF now shows a noticeably-deeper secondary low, closer to 993 rather than 995 mb.

[andyhb]

For this time of year, this is as impressive as I have ever seen in all except a few, top-end winter outbreaks like Super Tuesday or 01/24/1999.

 

You mean 1/21/99?

 

That was the big outbreak in Arkansas.

[brettjrob]

The process of backing refers to the counterclockwise turning of the wind, either spatially through a depth or temporally.  Winds can back, say from S to SE for example, on one surface or through a layer in time, often with the approach of a strengthening low pressure system.  Winds can also back with height at one given time, indicative of cold air advection, usually found behind a cold front.

 

This.

 

However, colloquially, I think many severe weenies typically just mean "anything more easterly than due S" when they say "the surface winds are backed." I'm guilty of this a lot. Technically, it should always be used in a relative sense, though.

[Ground Scouring]

You mean 1/21/99?

That was the big outbreak in Arkansas.

Yes, you are right; I just fixed it. I meant 1/21/1999, though I now think that 02/19/1884 might be a better analog than either that or Super Tuesday should model trends continue. Check the ESRL reanalysis; the evolution of the 1/30 system is actually rather similar to that of 02/19/1884, though the current system starts with a slight negative tilt and goes neutral and then positive (the 1884 trough was positively tilted). The reanalyzed 1884 surface set-up looks eerily similar to what is likely to occur based upon the models.

[SquatchinNY]

How would a stronger low, say...990-995mb, enhance or decrease the tornado threat?

[andyhb]

How would a stronger low, say...990-995mb, enhance or decrease the tornado threat?

 

Well for one, it would encourage stronger pressure falls over the warm sector, which would, in turn, encourage stronger low level shear via isallobaric backing of the low level winds. This also inflates deep layer directional shear by increasing the veering with height, say from SSE at the surface to SW at 500 mb.

 

This is not to say that the shear profiles aren't already mightily impressive across the warm sector...

[tornadotony]

Top 3 12z GFS CIPS analogs:

1) 3/9/92

2) 3/1/07

3) Super Tuesday

 

All have violent tornadoes, 2 and 3 obviously multiple.

[andyhb]

That's very impressive to see that with all three of the top analogs.

[OKpowdah]

Moisture return across Oklahoma today was pretty impressive. And we did end up clearing out for a few hours before sunset to be able to reach 68 in Norman. That was my biggest concern, that the warm airmass would just override shallow cold air for the next two days. Tomorrow could be really interesting temperature-wise if we cloud cover busts

[Ozarkwx]

The afternoon AFDs from LZK, TSA and SGF downplay the tornado threat, although of course not completely.  At the very least though, the chances for a much needed areawiderainfall event look pretty good.SPRINGFIELDTHE SEVERE WEATHER OUTLOOK IS A BIT MURKIER TODAY. THE FORECASTUPPER LEVEL PATTERN IS INCREASINGLY SUPPORTING A HEAVY RAINSIGNAL. STOUT UPPER LEVEL JET AND STRONG LOW LEVEL JET WILL BEORIENTED IN A PARALLEL FASHION FROM SOUTHWEST TO NORTHEAST ACROSSTHE MIDDLE OF THE NATION. 12Z SUITE OF MODEL OUTPUT INDICATES VERYLITTLE IF ANY MLCIN EARLY TUESDAY. WITH SUCH STRONG LARGE SCALESUPPORT...IT IS POSSIBLE THAT CONVECTION DEVELOPS EARLY TUESDAYMORNING JUST TO THE WEST/SOUTHWEST OF THE REGION AND RAPIDLYEXPANDS INTO THE REGION FROM WEST TO EAST TUESDAY MORNING. WITHPRECIPITABLE WATER VALUES IN THE 1.25 TO 1.5 INCH RANGE (99THPERCENTILE)...THIS SYSTEM SHOULD RESULT IN EFFICIENT RAINPRODUCTION. A WIDESPREAD ONE INCH OR GREATER RAINFALL ISEXPECTED...PARTICULARLY FOR AREAS ALONG AND SOUTHEAST OF A LINEFROM JOPLIN TO THE LAKE OF THE OZARKS. IF THE FORECAST PANSOUT...THIS WILL BE MOST WELCOME.FREELY CONVECTING EARLY MAY POTENTIALLY STYMIE THE EXTENT OF THESEVERE RISK AND THIS WILL NEED TO BE MONITORED WITH FUTUREFORECASTS. MLCAPE FROM THE 12Z MODELS IS LESS THAN PREVIOUSMODEL ESTIMATES...WITH 200 TO 600 J/KG EXPECTED IN OUR NECK OF THEWOODS. SHEAR WILL BE SUBSTANTIAL...AS IS TYPICALLY THE CASE INWINTER. THE ORIENTATION OF LOW LEVEL AND DEEP LAYER VECTORSINDICATE A PREFERRED LINEAR MODE OF CONVECTION. WITH A HIGHSHEAR/LOW CAPE ENVIRONMENT EXPECTED...THE PRIMARY SEVERE WEATHERRISK WILL BE DAMAGING STRAIGHT LINE WINDS. CANNOT COMPLETELY RULEOUT AN ISOLATED/BRIEF TORNADO RISK...THOUGH 0-3KM SHEAR VECTORORIENTATION DOES NOT LOOK IDEAL AT THIS TIME.WITH THE COLD FRONT BASICALLY PARALLEL TO THE UPPER LEVEL FLOWMUCH OF TUESDAY...EXPECTATIONS ARE FOR A SLOW WEST TO EASTPROGRESSION OF THIS SYSTEM. AS A RESULT...HAVE INCREASED POPSTUESDAY NIGHT ACROSS THE EASTERN HALF OF THE AREA.

 

TULSA

 

DATA STILL INDICATES THE POTENTIAL FOR THUNDERSTORMS TUESDAYACROSS EASTERN OK AND THEN EVENTUALLY WESTERN AR. THE ECMWFCONTINUES TO BE FARTHER WEST WITH THE INITIAL DEVELOPMENT...ANDTHIS POSSIBILITY LOOKS POSSIBLE...SO I HAVE PULLED THE HIGHER POPSBACK TO THE WEST SOME. THERE IS A LIMITED RISK OF SEVERE WEATHERMAINLY DUE TO THE PARALLEL FLOW TO THE FRONT...AND THE LACK OF AWELL DEFINED SURFACE LOW ALONG THIS PORTION OF THE FRONT. FLOWWILL BE VEERED OUT IN THE LOW LEVELS AHEAD OF THE FRONT...AND THISWILL NOT HELP STORMS TO BECOME ORGANIZED. GIVEN THE PARALLEL FLOWTO THE FRONT...A SQUALL LINE IS LIKELY TO FORM...WITH DAMAGINGWINDS POSSIBLE.

 

LITTLE ROCK

 

THERE IS ALSO A THREAT OF SEVERE STORMS WITH THE TUE SYSTEM. SHEAR

 

VALUES...BOTH 0-6 BULK AND 0-1KM/0-3KM HELICITY...WILL BE MORE THANSUPPORTIVE OF STRONG AND SEVERE THUNDERSTORMS WITH ROTATINGUPDRAFTS. LOW LEVEL MOISTURE WILL ALSO BE PLENTIFUL...FURTHER ADDINGTO THE POSSIBILITIES OF SEVERE WEATHER. HOWEVER...SFC AND ELEVATEDINSTABILITY VALUES STILL REMAIN ON THE LOW SIDE. THE 12Z GUIDANCESTILL SHOWS 300-800 J/KG CAPE VALUES. THE BIGGEST THREAT IS LIKELYTO BE STRONG WINDS GIVEN THE SHEAR PROFILES AND LACK OF STRONG CAPEIN THE HAIL GROWTH REGION. OVERALL LACK OF INSTABILITY MEANS THATISOLATED UPDRAFTS MAY BE SHEARED APART. HOWEVER...SHOULD UPDRAFTMAINTENANCE BE REALIZED...THE TORNADIC THREAT WILL CERTAINLY EXISTGIVEN SUCH SHEAR PROFILES. AGAIN THOUGH...THE BIGGEST THREATS OFSEVERE WEATHER WILL BE THE POTENTIAL FOR FLASH FLOODING ALONG WITHSOME HIGH WINDS RESULTING FROM DEVELOPING LINEAR THUNDERSTORMCOMPLEX TUE EVENING.

[Ground Scouring]

It looks as if the NWS discussions are placing much emphasis on the dampening of instability early morning 01/29 due to increased QPF output on the most recent 18Z NAM and WRF vs. 18Z runs yesterday (the same trend is also evident on the 12Z GFS today vs. 12Z yesterday). That would, in their view, reduce instability while subsidence ahead of the organizing QLCS along the cold front would delay further initiation in the warm sector until very late in the afternoon--when the QLCS would be too close and a strongly-forced squall line would evolve. But I believe that the models are still overdoing the convective initiation and will swing back as models have been underestimating the dry punch emanating from the Sonoran region this year.

Maybe the fact that CUmet has stopped posting indicates uncertainty here. Have several other people written off the outbreak? (I have not, but I am wondering given the lack of activity here.)

[Stebo]

It looks as if the NWS discussions are placing much emphasis on the dampening of instability early morning 01/29 due to increased QPF output on the most recent 18Z NAM and WRF vs. 18Z runs yesterday (the same trend is also evident on the 12Z GFS today vs. 12Z yesterday). That would, in their view, reduce instability while subsidence ahead of the organizing QLCS along the cold front would delay further initiation in the warm sector until very late in the afternoon--when the QLCS would be too close and a strongly-forced squall line would evolve. But I believe that the models are still overdoing the convective initiation and will swing back as models have been underestimating the dry punch emanating from the Sonoran region this year.

Maybe the fact that CUmet has stopped posting indicates uncertainty here. Have several other people written off the outbreak? (I have not, but I am wondering given the lack of activity here.)

 

No? The models haven't changed at all today, not much to discuss when things have remained the same.

[Ground Scouring]

No? The models haven't changed at all today, not much to discuss when things have remained the same.

True, but we are getting down to nowcasting re: the shortwave impulse that will be coming through the northern Plains late tomorrow evening and overnight. NWS offices go with SPC re: early convective feedback, while other indicators and past model performance suggest otherwise. I am sticking with my guns re: a major outbreak but also want to be attuned to the latest trends. Avoiding a bust is a serious matter here, and I do not make major forecasts lightly. This event has me more concerned about than I was for any previous winter event save Super Tuesday, and I think the potential is there for this event to match or exceed that event, though the threshold is narrow and the potential for a lower-end (but still significant) event is narrow.

[Buckeye05]

It looks as if the NWS discussions are placing much emphasis on the dampening of instability early morning 01/29 due to increased QPF output on the most recent 18Z NAM and WRF vs. 18Z runs yesterday (the same trend is also evident on the 12Z GFS today vs. 12Z yesterday). That would, in their view, reduce instability while subsidence ahead of the organizing QLCS along the cold front would delay further initiation in the warm sector until very late in the afternoon--when the QLCS would be too close and a strongly-forced squall line would evolve. But I believe that the models are still overdoing the convective initiation and will swing back as models have been underestimating the dry punch emanating from the Sonoran region this year.

Maybe the fact that CUmet has stopped posting indicates uncertainty here. Have several other people written off the outbreak? (I have not, but I am wondering given the lack of activity here.)

The potential for a significant severe event is definitely there, but people mentioning things like Enigma 1884 is overdoing it.

[OKpowdah]

That's +37F in Jay, OK!! Really impressive

 

[Stebo]

That's +37F in Jay, OK!! Really impressive

 

current.TDEW_24H.grad (2).png

 

Crazy WAA going on, all these models showing mid 60s for Tuesday are going to bust.

[Ground Scouring]

The potential for a significant severe event is definitely there, but people's mentioning things like Enigma 1884 is overdoing it.

Normally, I would agree, but not in this case. This case is highly unusual and we are closing in on the short-term lead-up to the event. The combined synoptics are as good as those for Super Tuesday, the moisture return (barring an underestimated QPF return/convection on the morning of 01/29) will be even better than on 02/05/2008, the instability will likely be close or equal to that of Super Tuesday (again, on the likelihood that the models are overdoing morning convection on 01/29, meaning greater instability in the warm sector), and the overall set-up is like a blend of 02/05/2008, 03/10/1992, and 02/19/1884. The historic potential is there if the morning convection--the one major fly in the ointment--does not materialize to the extent shown on the models. To me, that possibility is not only plausible but also likely. Also, I think the NWS offices are placing too much emphasis on the evolution of the surface low. Practically all of the CIP analogs plus the Enigma outbreak had a similarly elongated low, but the synoptics and thermodynamics aligned well and major events ensued, due primarily to the presence of a weakly-capped warm sector with a sufficient EML to keep a lid on early-morning convection, which in my view we will see again here. Calling the alarm at this stage is neither hyperbole nor hype when the overall set-up and model trends clearly box in the possibility that conditions, in overwhelming part, will be favorable for a high ceiling on an event barring one or two major flies in the proverbial ointment. Plus, current observations show that, just as before 02/05/2008, models are once again underestimating the WAA in advance of the initial shortwave impulse, which will only serve to draw that rich boundary layer even farther N than what is likely shown on even the most aggressive models at this time. If anything, the trend is pushing the limit toward a bigger and bigger ceiling, and given the dynamics at play, even the possibility of some initial convective activity becomes less likely to affect the general outcome. The difference essentially boils down to one between a significant outbreak by January standards--in the top-ten category, most likely--and a truly historic event like Super Tuesday or Enigma. The signs are growing and they are frightening, and even more so if everything aligns perfectly. And as I have mentioned in previous posts, I think that any significant outbreak that evolves would likely cover a very wide part of the South from the MS Valley all the way into the Carolinas, with two nocturnal outbreaks likely overnight 01/29-01/30 (in AL and TN) and again 01/30-01/31 (in GA and the Carolinas). The potential is there.

[OKpowdah]

Crazy WAA going on, all these models showing mid 60s for Tuesday are going to bust.

 

Problem is cloud cover. All this warm and moist advection could be enough to lock in clouds most of the day.

 

But if this evening was any indication, high temps could really soar if we can get some clearing

[tornadotony]

Problem is cloud cover. All this warm and moist advection could be enough to lock in clouds most of the day.

 

But if this evening was any indication, high temps could really soar if we can get some clearing

In the days leading up to 1/7/08, highs in the warm sector were busting 10-15 degrees even with solid cloud cover.  I don't buy sfc temps in these strong WAA events, clouds or no clouds.

[Ground Scouring]

For what it is worth, the 00Z radiosonde from DRT shows that the NAM is seriously underestimating both the dry punch and, to a lesser extent, the mid-level wet-bulb temperature. This makes for a stronger-than-forecasted EML tomorrow morning which should help bolster sunshine by early afternoon over N TX and OK, meaning even higher temperatures than what would have already occurred (meaning still very high) even with cloud cover.

Due to high LCL, warm mid-level temperatures, and weak LI, there might be some fairly large hail tomorrow with any discrete storms that form over OK in the late afternoon.

[Stebo]

In the days leading up to 1/7/08, highs in the warm sector were busting 10-15 degrees even with solid cloud cover.  I don't buy sfc temps in these strong WAA events, clouds or no clouds.

 

Agree with this completely. Hell even DTX is talking about hitting 60 on Tuesday, no model is showing that right now.

[brettjrob]

At the risk of flip-flopping several times, I'm becoming more skeptical now that instability will be sufficient for a major headline-making event. It's one thing for the GFS to show low CAPE primarily due to cool BL temps and cloud cover, but the ECMWF and NAM are very similar in their depictions of instability. Just about every model strongly suggests widespread initiation between 12-15z along the I-35 corridor. I agree with something that Tony said a few days ago: early initiation usually isn't a dealbreaker in Southeast events. But this event will (as currently modeled) be centered more over the Ozarks and Arklatex, and I believe widespread morning initiation will be quite detrimental to SigTor potential should it occur.

 

To put things into perspective, the SREF indicates no more than a 20% chance for SBCAPE exceeding 1000 J/kg over the entire warm sector Tuesday afternoon. We're within 48-60 hrs of game time, so that's difficult to ignore.

 

To be clear, I think instability is likely to verify higher than the ~250-600 J/kg SBCAPE painted by many models across AR. But in my view, it will have to be much higher -- widespread values of 1000-1500 J/kg -- in order for a significant outbreak of tornadic supercells to occur. Again, just based on subjective observation, I think the threshold is higher in the Ozarks than in Dixie.

 

I don't doubt the potential for several tornadoes, possibly a few significant, but I'm leaning more toward a messy/QLCS mode if initiation is focused during the morning hours. Of course, events like April 14 of last year remind us that even on strongly-forced days, convective parameterizations occasionally crap the bed completely inside of 24-48 hrs, so I'm not throwing in the towel. But from my memory, the instability progs for an event like Super Tuesday looked a good bit more impressive (at least on the NAM/ECMWF) at this range. I sure wish we could go back and look at those models for comparison, actually.

[Ground Scouring]

Compared to earlier runs, the incoming 00Z NAM now shows much lower LI values over much of AR and N LA in the mid-afternoon on 01/29. The change is extremely dramatic and, when adjusted for likely underestimations of instability and EML, brings values of -4 or greater as far north as LKZ and KHKA over much of the MS Valley by the late afternoon. The previous runs were showing nothing like this in terms of coverage and indicates a shift by the NAM toward a more-unstable warm sector on the afternoon of 01/29. Given the rapidly-evolving mesoscale terrain, there are still a good 24 hours left for models to continue evolving toward a higher ceiling for this event. So instability would likely not be compromised and SBCAPE in AR would likely be AOB 1000 j/kg. (For the first time, the NAM now actually shows close to 800 j/kg over AR in the late afternoon and overnight hours of 01/29-01/30, though it is slow to load the atmosphere until about 03Z 01/30.)

[chase_stormz]

Compared to earlier runs, the incoming 00Z NAM now shows much lower LI values over much of AR and N LA in the mid-afternoon on 01/29. The change is extremely dramatic and, when adjusted for likely underestimations of instability and EML, brings values of -4 or greater as far north as LKZ and KHKA over much of the MS Valley by the late afternoon. The previous runs were showing nothing like this in terms of coverage and indicates a shift by the NAM toward a more-unstable warm sector on the afternoon of 01/29. Given the rapidly-evolving mesoscale terrain, there are still a good 24 hours left for models to continue evolving toward a higher ceiling for this event. So instability would likely not be compromised and SBCAPE in AR would likely be AOB 1000 j/kg. (For the first time, the NAM now actually shows close to 800 j/kg over AR in the late afternoon and overnight hours of 01/29-01/30, though it is slow to load the atmosphere until about 03Z 01/30.)

I noticed that by 06z that instability actually increases across eastern AR to 750 per the 00z NAM. Interesting. 

[tornadotony]

At the risk of flip-flopping several times, I'm becoming more skeptical now that instability will be sufficient for a major headline-making event. It's one thing for the GFS to show low CAPE primarily due to cool BL temps and cloud cover, but the ECMWF and NAM are very similar in their depictions of instability. Just about every model strongly suggests widespread initiation between 12-15z along the I-35 corridor. I agree with something that Tony said a few days ago: early initiation usually isn't a dealbreaker in Southeast events. But this event will (as currently modeled) be centered more over the Ozarks and Arklatex, and I believe widespread morning initiation will be quite detrimental to SigTor potential should it occur.

 

To put things into perspective, the SREF indicates no more than a 20% chance for SBCAPE exceeding 1000 J/kg over the entire warm sector Tuesday afternoon. We're within 48-60 hrs of game time, so that's difficult to ignore.

 

To be clear, I think instability is likely to verify higher than the ~250-600 J/kg SBCAPE painted by many models across AR. But in my view, it will have to be much higher -- widespread values of 1000-1500 J/kg -- in order for a significant outbreak of tornadic supercells to occur. Again, just based on subjective observation, I think the threshold is higher in the Ozarks than in Dixie.

 

I don't doubt the potential for several tornadoes, possibly a few significant, but I'm leaning more toward a messy/QLCS mode if initiation is focused during the morning hours. Of course, events like April 14 of last year remind us that even on strongly-forced days, convective parameterizations occasionally crap the bed completely inside of 24-48 hrs, so I'm not throwing in the towel. But from my memory, the instability progs for an event like Super Tuesday looked a good bit more impressive (at least on the NAM/ECMWF) at this range. I sure wish we could go back and look at those models for comparison, actually.

I don't know about this.  The thing with the NAM is that even with nearly saturated profiles, it has steep low-level lapse rates and good low-level CAPE.  Above that, the lapse rates suck, but I would tend to think large-scale ascent would take over.  For instance, even with a mostly saturated column, this NAM sounding for 09z near Oxford, MS shows a solid amount of low-level CAPE, with total CAPE of 500-750J/kg depict across a large portion of MS at this time.  If you go back to 06z, the NAM has 750-1000J/kg of CAPE over a large portion of ern AR, with strong destabilization between 00z and 06z, owing to cooler mid-level temps advecting over the warm sector.  I don't think this issue is settled, but I don't think it's a big issue, at least yet.  I would still expect significant wind and tornado threats with this run of the NAM.