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

[OKpowdah]

You don't want temps that high.  Though you have pretty solid moisture near the sfc, it's pretty shallow, and any breaks in the clouds would support mixing of dry air to the sfc, eliminating any CAPE and making LCLs skyrocket.  You guys are just gonna need whatever lead impulse impacts the warm sector tonight to be enough to help sustain DMC.  If it is strong enough, then I don't see why a tornado or two won't happen as long as the drier air doesn't mix down.

 

Agreed. Sorry, I was just refering to temps. As anyone in the New England forum will tell you, I have a fetish for high wind events (that are truly mediocre) and anomalous temperatures

[scoresman]

Betting we will see a slight risk for Oklahoma for today....

[Buckeye05]

Betting we will see a slight risk for Oklahoma for today....

Maybe not. Tornadotony makes a good point. The clouds appear to be breaking up on satellite as we speak.

[JoMo]

Betting we will see a slight risk for Oklahoma for today....

 

Depends. The storms may fire around midnight or so if they do get going with the LLJ. Tulsa's new HWO at 1 PM mentions them:

 

 

THIS EVENING AND OVERNIGHT...SCATTERED THUNDERSTORMS MAY DEVELOPOVER PARTS OF NORTHEAST OKLAHOMA IN RESPONSE TO A STRENGTHENINGLOW LEVEL JET. MODERATE INSTABILITY AND STRONG WIND FIELDS WILLSUPPORT SEVERE POTENTIAL...INCLUDING A LOW RISK OF TORNADOES...IFSTORMS ARE ABLE TO DEVELOP. STORMS WILL BE MOST LIKELY AFTERMIDNIGHT ALONG AND NORTH OF THE INTERSTATE 44 CORRIDOR...BUTCANNOT BE RULED OUT BEFORE THEN.

[OKpowdah]

Maybe not. Tornadotony makes a good point. The clouds appear to be breaking up on satellite as we speak.

 

1) not really close to breaking up much. Not sure what you're looking at.

2) a little bit of sun would not be bad. I still argue that some breaks will go a long way. It's if we cleared out completely and started really mixing out the BL that there would be an issue.

[SquatchinNY]

What time are we looking at for tomorrow's initialization?

[RandomBlue]

1) not really close to breaking up much. Not sure what you're looking at.

2) a little bit of sun would not be bad. I still argue that some breaks will go a long way. It's if we cleared out completely and started really mixing out the BL that there would be an issue.

 

Sunny/partly sunny now here in NW Arkansas (Rogers/Bentonville) and we're up to 72 now, over the predicted high of 70.

[Disc]

What time are we looking at for tomorrow's initialization?

Read SPC's D2 forecast discussion.

[LocoAko]

D1 slight risk now issued for OK in the 20:00UTC outlook. 

[SquatchinNY]

Slight Risk now up for today.

[Chinook]

Has anybody seen a day-2 moderate in January before?

[brettjrob]

The 18z NAM is honing in on E KS into W MO between 06-09z with a robust QPF signal, and no significant inhibition for surface-based parcels. There's definitely precdent for nocturnal mischief in that area, too. Wouldn't be completely shocked to see a red box issued this evening should initiation become more certain.

 

Farther SW through OK and N TX, I'm skeptical of initiation before the "main round" along the cold front after sunrise, which should be more linear in nature. Should anything develop this evening, though, tornado potential would obviously be non-negligible.

 

Definitely one of those situations where mixing may be strong enough to keep a tornado threat in play well into the night, which isn't all that common in the Plains.

 

[chase_stormz]

The 18z NAM is honing in on E KS into W MO between 06-09z with a robust QPF signal, and no significant inhibition for surface-based parcels. There's definitely precdent for nocturnal mischief in that area, too. Wouldn't be completely shocked to see a red box issued this evening should initiation become more certain.

 

Farther SW through OK and N TX, I'm skeptical of initiation before the "main round" along the cold front after sunrise, which should be more linear in nature. Should anything develop this evening, though, tornado potential would obviously be non-negligible.

 

To be honest, I'm starting to think SPC is going to need to shift or expand the MOD risk nw to include most of AR and sc MO based on the recent trend that the 12z and 18z Nam has picked up on with secondary low development.

[andyhb]

Has anybody seen a day-2 moderate in January before?

 

Personally, I haven't.

[patrick7032]

D1 slight risk now issued for OK in the 20:00UTC outlook. 

I give up on trying to figure out SPC. I agree with their risk area...but it should extend southwest. I just looked at 850-500mb...700-500mb...and 850-700mb lapse rates...and effective shear. THEY'RE THE SAME...in areas from Sweetwater, TX northeast into the risk area...with similar instability. Any ideas?

[SquatchinNY]

I wish it wasn't so late, I can't stay up till 08z!

[brettjrob]

Personally, I haven't.

 

They must be lurking here, cause they just posted a list on FB of all such cases:

 

 

1999-01-21 (Valid on Jan. 22nd. Forecaster: Thompson): 43 tornadoes (2 F3), 1 fatal, 20 injuries; AL, AR, IL, KY, LA, MS, TN, TX (EST. $76M DAMAGES)

2000-01-02 (Valid on Jan. 3rd. Forecaster: Hart): 11 tornadoes (3 F3), 0 fatal, 21 injuries; AR, IN, KY, MS (EST. $72M DAMAGES)

2006-01-01 (Valid on Jan. 2nd. Forecaster: Kerr and continued by Carbin): 18 tornadoes (1 EF3), 0 fatal, 5 injuries; GA, FL, IL, KY, MO (EST. $7M DAMAGES)

2006-01-12 (Valid on Jan. 13th. Forecaster: Kerr): 19 tornadoes (no EF2+, 6 EF1), 1 fatal, 34 injuries, AL, FL, GA, LA, NC, SC, VA (EST. $7M DAMAGES)

[OKpowdah]

I give up on trying to figure out SPC. I agree with their risk area...but it should extend southwest. I just looked at 850-500mb...700-500mb...and 850-700mb lapse rates...and effective shear. THEY'RE THE SAME...in areas from Sweetwater, TX northeast into the risk area...with similar instability. Any ideas?

 

 

SW OK into northern TX is in good shape this afternoon, but the forcing for CI is later, and further northeast

[chase_stormz]

Nice write up from Jackson, MS AFD this afternoon.

 

 

 

...CONFIDENCE INCREASING FOR SIGNIFICANT SEVERE WEATHER EVENTTUESDAY NIGHT INTO EARLY WEDNESDAY...

 

 

 

CONFIDENCE CONTINUES TO INCREASE THIS AFTERNOON THAT SEVERE WEATHERWILL AFFECT MUCH OF THE FORECAST AREA FROM TUESDAY NIGHT INTOWEDNESDAY MORNING.  STILL AND AS EXPECTED... DESPITE SOME SUBTLEDISCREPANCIES IN TIMING AND CERTAIN PARAMETER SPECIFICS...MODELSOVERALL REMAIN IN GOOD AGREEMENT OF THIS SEVERE POTENTIAL EXISTING.TIMING CURRENTLY REMAINS THE TOUGHEST THING TO NAIL DOWN WITH THISSYSTEM.  THE GFS REMAINS THE FASTEST OUTLIER WITH THE NAM THESLOWEST...AND NOW THE ECMWF AND UKMET IN THE MIDDLE AS THEY`VE SPEDUP JUST A BIT THIS AFTERNOON.  THE SLOWER MODEL CONSENSUS STILLLOOKS TO BE THE WAY TO GO...THUS WILL STICK WITH THAT ROUTE FOR THETIME BEING.THE COMBINATION OF PLENTY OF WIND SHEAR (50-75 KNOTS 0-6KM...40-50KNOTS 0-1KM...AND 400-600M^2/S^2 SRH)...ADEQUATE INSTABILITY FORTHIS TIME OF YEAR (500-1000J/KG ML/MU CAPE)...AND STRONG FORCINGAHEAD OF A STRONG COLD FRONT AND UPPER LEVEL SYSTEM WILL SET THESTAGE FOR THIS LATE-JANUARY SEVERE RISK.  THE ENTIRE FORECAST AREAWILL SEE THIS RISK FOR SEVERE STORMS THAT`LL BE CAPABLE OF PRODUCINGDAMAGING WINDS UP TO 80 MPH AS WELL AS TORNADOES...SOME OF WHICHCOULD BE STRONG.  SOME DISCREET STORMS COULD DEVELOP OVER...OR MOVEINTO...THE WESTERN HALF OF THE CWA BEFORE MIDNIGHT TUESDAY NIGHT.IT`S HERE...THAT A MODERATE RISK FOR SEVERE STORMS CURRENTLY RESIDESFOR MY AREA TUESDAY NIGHT INTO WEDNESDAY MORNING.  A SLIGHT RISK FORSEVERE STORMS EXISTS ACROSS THE REMAINDER OF THE CWA.AS FAR AS THE TIMEFRAME FOR THIS POTENTIAL...IT CONTINUES TO LOOKLIKE IT`LL AFFECT THE MAJORITY OF THE CWA DURING THE NIGHT TIMEHOURS...BUT COULD PERHAPS LINGER FOR AN HOUR OR TWO AFTER SUNRISEOVER EAST CENTRAL AND SOUTHEAST MISSISSIPPI WEDNESDAY MORNING.  ALINE OF SEVERE STORMS IS EXPECTED TO ENTER MY WEST AND NORTHWESTCOUNTIES AND PARISHES BETWEEN 8PM-MIDNIGHT...THEN PROGRESS EAST NEARTO ALONG THE NATCHEZ TRACE PARKWAY BETWEEN 1-4AM...THEN FURTHER EASTOVER EAST CENTRAL AND SOUTHEAST MISSISSIPPI BETWEEN 5-8AM.  AGAIN...AND AS STATED ABOVE...SOME DISCREET STORMS COULD DEVELOP OUT AHEADOF THIS SQUALL LINE OVER MAINLY THE WESTERN HALF OF THE CWA THURSDAYNIGHT.

[Buckeye05]

That is much stronger wording compared to the discussion from the other offices.

[chase_stormz]

That is much stronger wording compared to the discussion from the other offices.

 

 

Shreveport, LA too..

 

.DISCUSSION...COMPLEX WEATHER SCENARIO SETTING UP OVER THE NEXT 24-36 HOURS...ASA SEVERE WEATHER OUTBREAK APPEARS TO BE SHAPING UP ACROSS THEREGION TUESDAY AFTERNOON AND ESPECIALLY TUESDAY NIGHT. VERY WARMAND HUMID CONDITIONS CONTINUE TO EXPAND N ACROSS A LARGE WARMSECTOR AS FAR N AS ERN KS INTO MUCH OF MO. BREAKS IN THE OVC HASALLOWED FOR TEMPS TO WARM WELL INTO THE 70S TO NEAR 80DEGREES...WITH THE RESULTANT MIXING ALLOWING FOR GUSTY SRLY WINDSESPECIALLY OVER E TX. THESE WINDS SHOULD CONTINUE TO REMAIN GUSTYOVER THE WRN SECTIONS OF E TX TONIGHT...IN RESPONSE TO A TIGHTPRESSURE GRADIENT IN PLACE OVER THE SRN PLAINS AHEAD OF DEVELOPINGSFC LOW PRESSURE OVER SE CO. WILL CARRY THE LAKE WIND ADVISORY FORTHE WRN SECTIONS OF E TX THROUGH 12Z TUESDAY...DROPPINGNACOGDOCHES AND ANGELINA COUNTIES AFTER THEIR ORIGINAL 00ZEXPIRATION. THE PRESSURE GRADIENT WILL TIGHTEN EVEN FURTHERTUESDAY AS THIS SFC LOW SLIDES SE ALONG A COLD FRONT...EVENTUALLYEJECTING NE ALONG THE FRONTAL ZONE INTO SE KS/WRN MO TUESDAYEVENING. THUS...A LAKE WIND ADVISORY WILL BE REQUIRED AREAWIDETUESDAY.WATER VAPOR IMAGERY INDICATES A LONGWAVE TROUGH BEGINNING TO SLIDEESE ACROSS THE GREAT BASIN INTO NRN BAJA THIS AFTERNOON...WHICHWILL CROSS THE ROCKIES TUESDAY MORNING BEFORE EMERGING OUT OVERTHE PLAINS BY AFTERNOON. THERE IS QUITE A SPREAD AMONGST THEMODELS TODAY IN THE EWD EXPANSION/TIMING OF THE DRY LINE/PRE-FRONTAL TROUGH TUESDAY...WITH THE GFS/ECMWF FASTEST IN RACING THISBNDRY E INTO WRN AR/E TX BY 00Z WEDNESDAY. MEANWHILE...THE 12 AND18Z WRF ARE A BIT SLOWER...NOT BRINGING IN THE BNDRY THROUGH THESEAREAS SEVERAL HOURS LATER. HAVE USED A BLEND HERE WITH REGARDS TOTIMING...WITH THE PRE-FRONTAL TROUGH SERVING AS A CONFLUENCE ZONEMAINLY AFTER 18Z ONCE LARGE SCALE FORCING INCREASES AHEAD OF THETROUGH. UNIDIRECTIONAL WINDS JUST AHEAD OF THIS BNDRY MAY ALLOWFOR A BRIEF PERIOD OF HEAVY RAINFALL/TRAINING MAINLY NW OF THEI-30 CORRIDOR OF NE TX/SE OK/SW AR. HOWEVER...ONCE BETTER FORCINGARRIVES FROM THE W BY MID TO LATE AFTERNOON...A SQUALL LINE SHOULDDEVELOP ALONG AND FARTHER S ALONG THE SFC TROUGH FROM ERNOK/ECNTRL TX...AND ACCELERATE E ACROSS THE REGION TUESDAY EVENING.FORECAST SOUNDINGS INDICATE THE CAPPING IN PLACE TUESDAY MORNINGSHOULD WEAKEN BY EARLY TO MID AFTERNOON...ALTHOUGH EXTENSIVE CLOUDCOVER MAY LIMIT THE EXTENT OF SFC BASED HEATING. THE SHORT TERMPROGS ALL AGREE UPON 500-1000 J/KG OF MLCAPE AVAILABLE IN THE WARMSECTOR...ALTHOUGH VERY STRONG WIND SHEAR SHOULD EASILY COMPENSATEFOR THE LIMITED INSTABILITY SUCH THAT CONVECTION SHOULD DEVELOPONCE LARGE SCALE FORCING INCREASES. IN FACT...A 55-60+ KT SWRLYLLJ WILL ONLY INCREASE BY AFTERNOON ACROSS N LA/S AR...WITH STEEPLAPSE RATES AHEAD OF THE NEGATIVE TILT TROUGH ONLY ENHANCINGINSTABILITY ALOFT AS 0-3KM HELICITIES RISE TO 300-450 M2/S2. THEWRF DOES INDICATE THE POTENTIAL FOR DISCRETE CONVECTION DEVELOPINGTUESDAY AFTERNOON AHEAD OF THE SFC TROUGH OVER N LA/SCNTRLAR...BEFORE THE SQUALL LINE DEVELOPS/ACCELERATES E ACROSS THEREGION TUESDAY EVENING. THE PROGS ALSO INDICATE THAT THE LLJ WILLINTENSIFY FURTHER TO NEAR 70KTS TUESDAY NIGHT OVER CNTRL/NELA...WHICH WILL ONLY ENHANCE THE DAMAGING WIND THREAT ONCE THISLINE REACHES THESE AREAS. ISOLATED TORNADOES WILL BE POSSIBLE FROMANY DISCRETE CELLS AHEAD OF THE LINE...AS WELL AS EMBEDDED WITHINTHE LINE ITSELF TUESDAY NIGHT.

[Ground Scouring]

Did not the WRF nail the convective evolution of 02/05/2008 better than did the main dynamical models GFS and ECMWF? I seem to recall that it did. Anyway, the slower movement of the NAM and WRF would favor sustained, discrete development as early as around 23Z 01/29, meaning that the cold pool will overspread the warm sector closer to the peak daytime heating (which will not matter in terms of the overall outbreak but would make a difference in terms of facilitating discrete storms ahead of the QLCS). Also, the WRF shows a broken series of confluence bands along and just ahead of the main QLCS bands which would indicate the potential for activity ahead of the front, as on 02/05/2008 in AR, as well as the likelihood of embedded supercell activity.

[brettjrob]

The AFD wording seems appropriate to me, in line with a substantial but not historic/extreme event. I also agree with the 45% hatched SWODY2, with an emphasis on wind damage and nocturnal QLCS tornadoes for much of the area. Based on current guidance, I'd probably go with an initial 10% hatched tornado risk on the midnight SWODY1 covering a large chunk of AR, N LA, W TN, NW MS and surrounding areas.

[chase_stormz]

Did not the WRF nail the convective evolution of 02/05/2008 better than did the main dynamical models GFS and ECMWF? I seem to recall that it did. Anyway, the slower movement of the NAM and WRF would favor sustained, discrete development as early as around 23Z 01/29, meaning that the cold pool will overspread the warm sector closer to the peak daytime heating (which will not matter in terms of the overall outbreak but would make a difference in terms of facilitating discrete storms ahead of the QLCS). Also, the WRF shows a broken series of confluence bands along and just ahead of the main QLCS bands which would indicate the potential for activity ahead of the front, as on 02/05/2008 in AR, as well as the likelihood of embedded supercell activity.

that's actually a very good point about the NAM

[Ground Scouring]

The AFD wording seems appropriate to me, in line with a substantial but not historic/extreme event. I also agree with the 45% hatched SWODY2, with an emphasis on wind damage and nocturnal QLCS tornadoes for much of the area. Based on current guidance, I'd probably go with an initial 10% hatched tornado risk on the midnight SWODY1 covering a large chunk of AR, N LA, W TN, NW MS and surrounding areas.

I know this question may seem inappropriate...but I had thought that you would trend a bit higher with the TOR risk than 10% given the model and thermodynamic trends. Am I missing something? Or do you envision larger probabilities for the second SWODY1 on 01/29? Maybe I have not been following other people's thoughts well enough, but I tend to lean closer to initial probabilities a bit higher than 10%. (The WRF actually generates discrete supercell thunderstorms in the first confluence band in W AR as early as 22Z tomorrow.)

[Ground Scouring]

To be put the point bluntly (and this is for my own learning), aside from concerns about early cloud cover and the precipitation shield from morning convection, is there anything that really precludes a higher-end event? Assuming that the trend toward an open warm sector holds, I really do not see anything of significance that would mitigate this possibility, for the lapse rates and low-level turning would be there along with the instability. Simply based upon raw parameters, the set-up to me does look very similar to that of Super Tuesday, though the aerial extent of similar instability is more limited and the moisture column shallower in this case. Of course I would not expect a big bunch of violent tornadoes, but I think that the local conditions would favor very prolific supercell activity that would be the equal of that on 02/05-02/06/2008, albeit in a narrower area. That would still translate to many significant tornadoes--I would guess about 10 EF2+ events--and likely one or two violent tornadoes. To me, that is still close enough to Super Tuesday-like levels to be ranked alongside that outbreak and a few others as being among the top ten cold-season outbreaks, though not at the very summit of the heap.

[brettjrob]

I know this question may seem inappropriate...but I had thought that you would trend a bit higher with the TOR risk than 10% given the model and thermodynamic trends. Am I missing something? Or do you envision larger probabilities for the second SWODY1 on 01/29? Maybe I have not been following other people's thoughts well enough, but I tend to lean closer to initial probabilities a bit higher than 10%. (The WRF actually generates discrete supercell thunderstorms in the first confluence band in W AR as early as 22Z tomorrow.)

 

Simply put, I'm still not very impressed with the thermodynamics nor the potential for widespread, discrete development out ahead of the front tomorrow afternoon. Any positive thermodynamic trends in the guidance have been relatively minor, particularly for the period prior to sunset. If we don't have discrete supercells by mid-late evening, it seems improbable that a swarm of them will initiate late at night, when thermodynamics over the mid South admittedly become a bit more favorable.

 

IMO, if these concerns prove founded, the event ceiling will be substantially lower than anything resembling Super Tuesday. Of course, it doesn't take multiple long-track monster supercells to get quite a few tornado reports, nor to cause multiple fatalities (especially at night in the Southeast). That's why I still think this could well be a "substantial" event or moderate outbreak. Right now my window of expected magnitude centers on something like 12/31/10 or 1/7/08 from Tony's post last night, which were nothing to sneeze at.

[blackjack123]

To be put the point bluntly (and this is for my own learning), aside from concerns about early cloud cover and the precipitation shield from morning convection, is there anything that really precludes a higher-end event? Assuming that the trend toward an open warm sector holds, I really do not see anything of significance that would mitigate this possibility, for the lapse rates and low-level turning would be there along with the instability. Simply based upon raw parameters, the set-up to me does look very similar to that of Super Tuesday, though the aerial extent of similar instability is more limited and the moisture column shallower in this case. Of course I would not expect a big bunch of violent tornadoes, but I think that the local conditions would favor very prolific supercell activity that would be the equal of that on 02/05-02/06/2008, albeit in a narrower area. That would still translate to many significant tornadoes--I would guess about 10 EF2+ events--and likely one or two violent tornadoes. To me, that is still close enough to Super Tuesday-like levels to be ranked alongside that outbreak and a few others as being among the top ten cold-season outbreaks, though not at the very summit of the heap.

   I do tend to agree with you on this because some of things you guys have mentioned. My guess would be about what yours is. Like a half dozen or so EF2's, a few EF3's, and a couple EF4's or EF5's. It may end up being a pretty solid tornado outbreak IMHO. Probably at least a solid moderate risk(10-15% hatched) with at least one or two of the tornadoes being possibly violent(EF4 or EF5) and maybe as high as 40 tornadoes confirmed. This is just my opinion though. We will all see what happens. You do well when understanding the possible magnitude up this upcoming event.

[CUmet]

Simply put, I'm still not very impressed with the thermodynamics nor the potential for widespread, discrete development out ahead of the front tomorrow afternoon. Any positive thermodynamic trends in the guidance have been relatively minor, particularly for the period prior to sunset. If we don't have discrete supercells by mid-late evening, it seems improbable that a swarm of them will initiate late at night, when thermodynamics over the mid South admittedly become a bit more favorable.

 

IMO, if these concerns prove founded, the event ceiling will be substantially lower than anything resembling Super Tuesday. Of course, it doesn't take multiple long-track monster supercells to get quite a few tornado reports, nor to cause multiple fatalities (especially at night in the Southeast). That's why I still think this could well be a "substantial" event or moderate outbreak. Right now my window of expected magnitude centers on something like 12/31/10 or 1/7/08 from Tony's post last night, which were nothing to sneeze at.

 

My thoughts are similar to yours.  My main concerns are that the capping will hold across much of the warm sector ahead of the main line, and that the low-level moisture will mix out to some extent during the afternoon particularly closer to the MS river.  Thermodynamics do improve somewhat after dark, but it remains to be seen how linear the convection will be by then.  Still, given the crazy wind fields and the presence of quality moisture after dark, a decent tornado outbreak may well occur.

[brettjrob]

And I present... a sounding we'll probably be begging for even in April and May when there is convection. Torture.