Severe Weather Threat in Dixie Alley/OV Feb 27 - Mar 1

[Hoosier]

Think we would be able to vaporize this snow by that time? I'm sure you will have a much better go at it than us though.

I imagine much of it will be gone by Sunday night. As csnavy said, the hail threat is very much in play as the NAM is really hinting at some respectable MUCAPE Sunday night.

I would imagine that the SPC risk area would expand north to cover the hail threat if this holds up. More questionable is how much surface based instability will be realized this far north.

[Thundersnow12]

18z NAM coming in a bit weaker with the sfc low and slower and now keeping the dryline west of I-35 in OK at 0z. The capping issues are a concern for me and think your best bet might be further north near the triple point.

[Kevin Askew]

SPECIAL WEATHER STATEMENT

NSPECIAL WEATHER STATEMENT

NATIONAL WEATHER SERVICE PADUCAH KY

209 PM CST FRI FEB 25 2011

...SEVERE WEATHER OUTLOOK FOR SUNDAY EVENING THROUGH MONDAY MORNING...

THE MODELS CONTINUE TO INDICATE A SEVERE WEATHER OUTBREAK IS POSSIBLE

ACROSS SOUTHEAST MISSOURI...SOUTHERN ILLINOIS...SOUTHWEST INDIANA AND

WESTERN KENTUCKY...MAINLY OVERNIGHT SUNDAY INTO THE EARLY MORNING

HOURS MONDAY.

STRONG LOW PRESSURE AND A VIGOROUS UPPER LEVEL SYSTEM ARE FORECAST

TO TRACK NORTHEAST FROM THE CENTRAL PLAINS SUNDAY EVENING TO THE

OHIO VALLEY REGION BY MIDDAY MONDAY. THE MODELS INDICATE STRONG WIND

FIELDS AND UNSTABLE ATMOSPHERIC CONDITIONS COULD LEAD TO STRONG TO

SEVERE CONVECTION ACROSS THE FOUR STATE AREA...ESPECIALLY OVERNIGHT

SUNDAY INTO THE EARLY MORNING HOURS MONDAY.

THE MODELS CONTINUE ADJUST THEIR STORM TRACK AND OVERALL TIMING

SLIGHTLY...BUT THERE HAS BEEN A DECENT DEGREE OF CONSISTENCY THAT

HAS INCREASED OUR CONFIDENCE THAT THERE IS AT LEAST A CHANCE OF A

SEVERE WEATHER OUTBREAK. SHOULD ALL THE FORECAST PARAMETERS COME

TOGETHER...LARGE HAIL...DAMAGING WINDS AND PERHAPS TORNADOES WILL

ALL BE POSSIBLE.

OUR CONCERN LEVEL IS ELEVATED TOO...BY THE FACT THAT THE EVENT IS

FORECAST TO OCCUR LATE IN THE WEEKEND...AND AT A TIME OF DAY NOT

TYPICALLY THOUGHT OF AS ONE WHEN WE WOULD HAVE SEVERE WEATHER. LATE

NIGHT AND EARLY MORNING EVENTS ARE PARTICULARLY DANGEROUS.

THE EVENT IS A LITTLE OVER TWO DAYS AWAY...SO ADJUSTMENTS TO THE

THREAT LEVEL MAY BE MADE. HOWEVER...NOW IS THE TIME TO THINK

ABOUT AND REVIEW YOUR TORNADO EMERGENCY PLAN OF ACTION. IT IS

STILL A BIT TOO SOON TO SAY WITH HIGH CONFIDENCE THERE WILL BE AN

OUTBREAK...BUT THE MODELS INDICATE THERE IS AT LEAST THE CHANCE.

$$

NOLES

ATIONAL WEATHER SERVICE PADUCAH KY

209 PM CST FRI FEB 25 2011

[thewxmann]

Timing is off with this system. I think the CAP will be too much to overcome on Sunday. Many models also hint at low clouds covering the warm sector much of the day.

Unfortunately, it does look like the threat ramps up significantly after dark for areas further east, and that will be the best chance for tornadic activity.

[Kevin Askew]

Latest SREF runs looking very ominous for Our area Sunday night and overnight........

[Thundersnow12]

Increased from the 9z run for the threat up this way.

[CUmet]

Timing is off with this system. I think the CAP will be too much to overcome on Sunday. Many models also hint at low clouds covering the warm sector much of the day.

Unfortunately, it does look like the threat ramps up significantly after dark for areas further east, and that will be the best chance for tornadic activity.

The capping very well could become an issue if the trough arrives slower than currently progged. Even now it looks enough to prevent early initiation (before 22z). However, the NAM and GFS are almost certainly grossly underestimating the surface temps in the warm sector. They always do this, every single freaking time. Every once in a while that super-thick low-cloud deck actually does verify, but it's usually in the cases where you get lots of morning convection, which won't happen this time (note the strong elevated mixed layer and no morning QPF on any of the models). In contrast, the ECMWF has surface temps about 5-9 degrees F higher than the NAM/GFS, and it verified much better with yesterday's event.

[Macintosh]

Latest SREF runs looking very ominous for Our area Sunday night and overnight........

Yeah, if this comes rolling through at 2am it really is dangerous, especially on a Sunday night when everyone really is asleep.

[Macintosh]

NWS Paducah has a great conference call they do for severe events. Here's the link to the page. The Feb 24 event is currently up, but they mention the next event in the presentation. Look for further updates tomorrow.

http://www.crh.noaa.gov/pah/?n=briefs

[JoMo]

Tulsa's AFD about the cooler and cloudier possibility.

GIVEN THE TIME OF
YEAR...I.E. THE TAIL END OF THE COOL SEASON...THERE HAVE BEEN
SITUATIONS WHEN THE AMOUNT OF MOISTURE ADVECTION IS TOO GREAT IN
THE WARM SECTOR FOR THE AIR MASS TO HANDLE...AND THUS THE WARM
SECTOR STAYS CLOUDY AND COOLER. THE MODELS ARE HINTING THAT THIS
MAY BE CASE...AND THIS WILL LIMIT POTENTIAL INSTABILITY.

[David Reimer]

Tulsa HWO

EXTENDED DISCUSSION... A MAJOR STORM SYSTEM WILL APPROACH THE AREA FROM THE WEST LATE IN THE WEEKEND. AHEAD OF THIS SYSTEM... ISOLATED THUNDERSTORMS MAY DEVELOP SATURDAY NIGHT IN PARTS OF SOUTHEAST OKLAHOMA AND NORTHWEST ARKANSAS. THE MAIN EFFECTS FROM THIS STORM SYSTEM WILL BE FELT LATE SUNDAY AND SUNDAY EVENING AS SURFACE LOW PRESSURE MOVES FROM SOUTHEAST COLORADO INTO NORTHWEST OKLAHOMA BEFORE EJECTING NORTHEAST INTO ILLINOIS BY MONDAY MORNING. SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG A DRYLINE TO OUR WEST NEAR INTERSTATE 35 LATE SUNDAY AFTERNOON AND MOVE RAPIDLY EAST INTO EASTERN OKLAHOMA AND NORTHWEST ARKANSAS BY SUNDAY EVENING. A COLD FRONT TRAILING FROM THE LOW WILL OVERTAKE THE DRYLINE SUNDAY EVENING... WITH THE POSSIBILITY OF A SQUALL LINE DEVELOPING ALONG THE COLD FRONT AS IT SWEEPS RAPIDLY EAST ACROSS THE AREA LATE SUNDAY EVENING.

SEVERE WEATHER POTENTIAL LOOKS HIGH LATE SUNDAY AND SUNDAY EVENING WITH TORNADOES...LARGE HAIL AND DAMAGING WINDS ALL POSSIBLE.

EMERGENCY MANAGEMENT PLANNING STATEMENT... MONITOR THE LATEST FORECASTS AND DISCUSSIONS CONCERNING SEVERE WEATHER POTENTIAL LATE THIS WEEKEND.

[brettjrob]

The capping very well could become an issue if the trough arrives slower than currently progged. Even now it looks enough to prevent early initiation (before 22z). However, the NAM and GFS are almost certainly grossly underestimating the surface temps in the warm sector. They always do this, every single freaking time. Every once in a while that super-thick low-cloud deck actually does verify, but it's usually in the cases where you get lots of morning convection, which won't happen this time (note the strong elevated mixed layer and no morning QPF on any of the models). In contrast, the ECMWF has surface temps about 5-9 degrees F higher than the NAM/GFS, and it verified much better with yesterday's event.

Fully agree that the NAM/GFS are underdoing sfc temps, and therefore capping. However, in terms of tornado potential, I still see veering low-level flow as Sunday's downfall unless things change substantially in the direction of a stronger surface/H85 low.

The models are now coming into agreement that the triple point should be somewhere between DDC and ICT by late Sunday afternoon, with a dryline draped across W OK and NW TX. This is an area that cannot afford H85 winds that veer much more than SSW without horribly mixing out low-level moisture. Indeed, you can see on tonight's NAM the surface dew points dropping off over the course of the afternoon along and east of the dryline. Unlike areas farther E into the Ozarks, out here we simply never get away with H85 dew points below 0 C (as the NAM shows) and still see significant tornado activity.

Overall, I'm thinking either a cap bust or messy nontornadic supercells that might look deceivingly impressive on radar but fall victim to high LCL's. But, of course, things can still change. Also, it might be a different story farther E overnight if storms can sustain themselves and remain surface-based that long.

[David Reimer]

The 0Z NAM is extremely concerning. If its solution were to play out, discrete supercells capable of producing substantial tornadoes would be possible in Oklahoma most of Sunday Night after 9 PM with that thread spreading east as the night goes on.

[Thundersnow12]

The 0Z NAM is extremely concerning. If its solution were to play out, discrete supercells capable of producing substantial tornadoes would be possible in Oklahoma most of Sunday Night after 9 PM with that thread spreading east as the night goes on.

popping a discrete cell just east of the DL at 6z beneath a 50kt LLJ...still have to go and look at this run more in depth but that caught my eye.

[JoMo]

it's going to "line out" rather quickly.

[brettjrob]

The 0Z NAM is extremely concerning. If its solution were to play out, discrete supercells capable of producing substantial tornadoes would be possible in Oklahoma most of Sunday Night after 9 PM with that thread spreading east as the night goes on.

popping a discrete cell just east of the DL at 6z beneath a 50kt LLJ...still have to go and look at this run more in depth but that caught my eye.

I admit I didn't wait for the run to get out to 06z before making that last post... this does look quite interesting for a nocturnal threat across E OK. The CINH actually erodes significantly after dark, which I didn't really see coming, lol.

Hodos look a little funky with some veer-back-veer action going on in the H85-H5 layer, but something to keep an eye on.

[David Reimer]

Fully agree that the NAM/GFS are underdoing sfc temps, and therefore capping. However, in terms of tornado potential, I still see veering low-level flow as Sunday's downfall unless things change substantially in the direction of a stronger surface/H85 low.

The models are now coming into agreement that the triple point should be somewhere between DDC and ICT by late Sunday afternoon, with a dryline draped across W OK and NW TX. This is an area that cannot afford H85 winds that veer much more than SSW without horribly mixing out low-level moisture. Indeed, you can see on tonight's NAM the surface dew points dropping off over the course of the afternoon along and east of the dryline. Unlike areas farther E into the Ozarks, out here we simply never get away with H85 dew points below 0 C (as the NAM shows) and still see significant tornado activity.

Overall, I'm thinking either a cap bust or messy nontornadic supercells that might look deceivingly impressive on radar but fall victim to high LCL's. But, of course, things can still change. Also, it might be a different story farther E overnight if storms can sustain themselves and remain surface-based that long.

I do see what you mean with the NAM showing some mixing out at 850 MB, but assuming most of the convection will occur just after dark and combined with the decent ground moisture we have in place, I don't know how much of an issue we will have with surface based storms. The hodographs by 9 PM look good along and ahead of the dryline with the development of the nocturnal LLJ. The NAM keeps the dewpoints around 60F which may create somewhat higher LCL's if we get to about 80F, but the moment the sun sets (assuming convection fires before dark) the LCLs will quickly lower. While your solution may be correct, I'm betting SPC beefs up the wording with the upcoming outlook. At least we have storms coming back to Oklahoma again

EDIT: Figures you'd respond to my post about 30 seconds before I posted this.

[wxsmwhrms]

The capping very well could become an issue if the trough arrives slower than currently progged. Even now it looks enough to prevent early initiation (before 22z). However, the NAM and GFS are almost certainly grossly underestimating the surface temps in the warm sector. They always do this, every single freaking time. Every once in a while that super-thick low-cloud deck actually does verify, but it's usually in the cases where you get lots of morning convection, which won't happen this time (note the strong elevated mixed layer and no morning QPF on any of the models). In contrast, the ECMWF has surface temps about 5-9 degrees F higher than the NAM/GFS, and it verified much better with yesterday's event.

Given that I forecast in the "Dixe Alley" area we get a lot of overnight events, and they also do this at night in these types of situations as you say EVERY FREAKING TIME. You look at the instability in the warm sector overnight Sunday night and it's only like 500 J/kg over the mid-South and almost nothing farther S. But that's because it shows the low levels unmixed and saturated in spite of like 15-20 kt of surface flow and a 60-70 kt LLJ. The GFS and NAM always underdo the instability in these types of events, although the NAM will catch up many time as you get within 24-36 hours. Last night was a prime example, temperatures stayed in the lower 70s ahead of that squall line while the GFS/NAM had been showing them in the mid 60s.

BTW, am guessing the NAM is probably 6-12 hours too slow on this system, at least based on the ECMWF which was the slowest of the other main models at 12Z.

[brettjrob]

BTW, am guessing the NAM is probably 6-12 hours too slow on this system, at least based on the ECMWF which was the slowest of the other main models at 12Z.

Assuming this means you have full access... what was the approximate dryline position at 00z Mon?

[tornadotony]

Given that I forecast in the "Dixe Alley" area we get a lot of overnight events, and they also do this at night in these types of situations as you say EVERY FREAKING TIME. You look at the instability in the warm sector overnight Sunday night and it's only like 500 J/kg over the mid-South and almost nothing farther S. But that's because it shows the low levels unmixed and saturated in spite of like 15-20 kt of surface flow and a 60-70 kt LLJ. The GFS and NAM always underdo the instability in these types of events, although the NAM will catch up many time as you get within 24-36 hours. Last night was a prime example, temperatures stayed in the lower 70s ahead of that squall line while the GFS/NAM had been showing them in the mid 60s.

BTW, am guessing the NAM is probably 6-12 hours too slow on this system, at least based on the ECMWF which was the slowest of the other main models at 12Z.

Classic NAM phase shift problem.

[wxsmwhrms]

Assuming this means you have full access... what was the approximate dryline position at 00z Mon?

Sorry, I was looking at it at work and focused more farther east, so I am hesitant to give you the exact position but I believe it was a little E of I-35. And just to clarify, I meant later in the forecast period when the phase shift errors TT mentions have obviously grown - so the error wouldn't be quite that dramatic Sunday evening. Still, it looks slow, which at TT said is not unusual.

[brettjrob]

Sorry, I was looking at it at work and focused more farther east, so I am hesitant to give you the exact position but I believe it was a little E of I-35. And just to clarify, I meant later in the forecast period when the phase shift errors TT mentions have obviously grown - so the error wouldn't be quite that dramatic Sunday evening. Still, it looks slow, which at TT said is not unusual.

Not a problem -- thanks for the estimate.

I do see what you mean going into Monday morning. The H5 trough axis is almost identical (over Needles) on both models at 12z Sun, but by 12z Mon there's a difference of about 200 miles. This will probably have some implications on Sunday, albeit not as large as Monday.

[CUmet]

Given that I forecast in the "Dixe Alley" area we get a lot of overnight events, and they also do this at night in these types of situations as you say EVERY FREAKING TIME. You look at the instability in the warm sector overnight Sunday night and it's only like 500 J/kg over the mid-South and almost nothing farther S. But that's because it shows the low levels unmixed and saturated in spite of like 15-20 kt of surface flow and a 60-70 kt LLJ. The GFS and NAM always underdo the instability in these types of events, although the NAM will catch up many time as you get within 24-36 hours. Last night was a prime example, temperatures stayed in the lower 70s ahead of that squall line while the GFS/NAM had been showing them in the mid 60s.

BTW, am guessing the NAM is probably 6-12 hours too slow on this system, at least based on the ECMWF which was the slowest of the other main models at 12Z.

Yeah the models hardly ever mix the boundary layer sufficiently enough, day or night. I agree with the skepticism of the NAM phase speed, as it has a pretty horrible slow bias.

Also, and I have no real way to substantiate this other than my own subjective experience, but over the years it always seems that the GFS veers the surface winds too quickly compared to verification, and also compared to the NAM. However, the positive tilt of this trough and the strung-out forcing gives this scenario some credibility.

The 12z ECMWF has the dryline just east of I-35 at 00z, and just west of the OK/AR border (near 95W) at 06z.

[David Reimer]

Yeah the models hardly ever mix the boundary layer sufficiently enough, day or night. I agree with the skepticism of the NAM phase speed, as it has a pretty horrible slow bias.

Also, and I have no real way to substantiate this other than my own subjective experience, but over the years it always seems that the GFS veers the surface winds too quickly compared to verification, and also compared to the NAM. However, the positive tilt of this trough and the strung-out forcing gives this scenario some credibility.

The 12z ECMWF has the dryline just east of I-35 at 00z, and just west of the OR/AR border (near 95W) at 06z.

I thought the chase terrain in Arkansas was bad

[wxsmwhrms]

Yeah the models hardly ever mix the boundary layer sufficiently enough, day or night. I agree with the skepticism of the NAM phase speed, as it has a pretty horrible slow bias.

Also, and I have no real way to substantiate this other than my own subjective experience, but over the years it always seems that the GFS veers the surface winds too quickly compared to verification, and also compared to the NAM. However, the positive tilt of this trough and the strung-out forcing gives this scenario some credibility.

The 12z ECMWF has the dryline just east of I-35 at 00z, and just west of the OK/AR border (near 95W) at 06z.

Part of it may be that the GFS just does not seem to lower pressures enough along cold fronts/dryline as it would seem holding on to lower pressures would keep the flow backed more. Now that we have the ECMWF in much better spatial and temporal resolution, find myself utilizing it more and more for that type of thing. NAM is better for it too, although you have to usually adjust its timing forward several hours. EC shows the surface low and associated pressure trough several mb lower with this system than the GFS. Did the same thing with yesterday's event, and was correct.

As far as the speed, at 18Z Monday the GFS has the upper system over IN and the NAM has it over SW MO. Little bit of difference, and from what I can see on the coarse web stuff, would think the ECMWF is between the two.

[Hoosier]

Thinking we will get our first slight risk (well I think it would be the first) of the season here. Models remain relatively consistent in showing decent elevated instability for a hail threat late Sunday into Monday. As has been mentioned, model surface temps in the warm sector are probably underdone and that will need to be watched. Given questions about the thermodynamic environment this far north, I'm not sure about other possible severe threats but suppose a conditional wind/isolated tornado threat could develop if storms are near surface based.

[SmokeEater]

DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1254 AM CST SAT FEB 26 2011

VALID 271200Z - 281200Z

...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS SRN PLAINS...ARKLATEX

TO LOWER OH VALLEY REGION...

...SYNOPSIS...

UPPER-AIR PATTERN FCST TO REMAIN QUASI-ZONAL ACROSS MOST OF

CONUS...PRIMARY PERTURBATION BEING STG SHORTWAVE TROUGH AND EMBEDDED

LOW LOCATED OVER NRN CA AS OF 26/05Z. THIS FEATURE IS FCST TO DIG

SSEWD THEN TURN EWD ACROSS LOWER CO RIVER VALLEY AREA NEAR START OF

PERIOD. GIVEN SLIGHTLY LAGGED UPSTREAM PATTERN OF HEIGHT FALLS AND

RUN-TO-RUN TRENDS IN PROGS...WILL MAINTAIN EARLY-PERIOD FCST CLOSER

TO CONSISTENTLY SLOWER ECMWF POSITION...AS OPPOSED TO FASTER

OPERATIONAL SPECTRAL...WITH 500-MB CYCLONE POSITIONED OVER LAS-EED

AREA AT START OF PERIOD. THIS ALSO RESEMBLES ETA MEMBERS OF SREF.

TROUGH IS FCST TO ASSUME PRONOUNCED POSITIVE TILT EARLY IN PERIOD

AND DEVOLVE TO OPEN WAVE...MOVING EWD TO AXIS FROM CENTRAL HIGH

PLAINS TO S-CENTRAL/SWRN NM BY 28/00Z. TROUGH THEN SHOULD MOVE EWD

BY 28/12Z TO NEAR KS/MO BORDER...SERN OK...AND N-CENTRAL TX...BY

WHICH TIME ECMWF ACCELERATES SYSTEM INTO SREF MEAN POSITION.

AT SFC...LEE TROUGHING OVER CO LATE DAY-1 SHOULD CONSOLIDATE RAPIDLY

INTO STG SFC CYCLONE THERE BY ABOUT 27/18Z AS UPPER WAVE

APCHS...WITH WARM FRONT EWD ACROSS PORTIONS KS/MO. SFC LOW THEN

SHOULD PIVOT SEWD/EWD OVER SRN KS DURING AFTERNOON/EVENING. SFC LOW

PRESSURE THEN SHOULD BECOME ELONGATED SW-NE ALONG SFC FRONTAL ZONE

BY END OF PERIOD...WITH NEWER CENTER POSSIBLE OVER LOWER MI AND

ORIGINAL LOW OVER MO OR IL. COLD FRONT TRAILING SFC LOW WILL MOVE

EWD FROM CENTRAL/SRN ROCKIES ACROSS OK AND MOST OF TX BY 28/12Z.

DRYLINE SHOULD MOVE EWD ACROSS PORTIONS CENTRAL/N-CENTRAL TX AND

CENTRAL/ERN OK DURING AFTERNOON/EVENING...INTERSECTING FRONTAL ZONE

NEAR S-CENTRAL/SERN KS SFC LOW.

...SRN PLAINS...ARKLATEX TO LOWER OH VALLEY REGION...

MOST CONCENTRATED AND SIGNIFICANT SVR THREAT IS FCST DURING

EVENING/OVERNIGHT HOURS IN AND NEAR OZARKS...WITH MORE CONDITIONAL

SVR RISK BEGINNING AS EARLY AS MID-LATE AFTERNOON AND AS FAR W AS

CENTRAL/ERN PORTIONS OF KS/OK. BULK OF SVR EVENTS SHOULD BE

DAMAGING WIND...ALTHOUGH A FEW STG TORNADOES AND LARGE/DAMAGING HAIL

ALSO ARE POSSIBLE.

INITIAL/DIURNAL CONVECTIVE DEVELOPMENT...AND TSTM COVERAGE THROUGH

AROUND 28/00Z...REMAIN RATHER UNCERTAIN/CONDITIONAL...AS AREAS ALONG

AND E OF DRYLINE OVER SRN KS...NE TX AND OK SHOULD BE CAPPED FOR

MOST OF AFTERNOON BENEATH ELEVATED MIXED-LAYER AIR. ISOLATED SVR

TSTMS ARE POSSIBLE...WHICH COULD INCLUDE SUPERCELLS.

EXPECT MAJOR INCREASE IN CONVECTIVE COVERAGE DURING 28/00Z-28/06Z AS

LIFT STRENGTHENS ON ALL SCALES...AND STRONGER FORCING IMPINGES UPON

PROGRESSIVELY MORE MOIST LOW-LEVEL AIR MASS. KINEMATIC ENVIRONMENT

WILL BECOME MORE FAVORABLE WITH TIME DURING AFTERNOON/EVENING AS

STRENGTHENING FLOW AND ASCENT ALOFT SPREADS OVER PROGRESSIVELY

MOISTENING WARM SECTOR E OF DRYLINE. LEFT-EXIT REGION OF

INTENSIFYING...SOMEWHAT CYCLONICALLY CURVED...125-150 KT 250-MB JET

WILL BE SPREADING ACROSS MUCH OF OK...KS...OZARKS AND INTO LOWER OH

VALLEY REGION DURING LATTER HALF OF PERIOD. MEANWHILE...EXPECT

BROAD AREA OF 60-80 KT 500-MB WINDS TO SPREAD OVER SVR RISK AREAS

DURING EVENING AND OVERNIGHT...CONTRIBUTING TO FAVORABLE DEEP-LAYER

SHEAR...E.G. EFFECTIVE SHEAR MAGNITUDES 50-60 KT IN MANY FCST

SOUNDINGS. LOW-LEVEL HODOGRAPHS ALSO WILL ENLARGE CONSIDERABLY

AFTER 00Z FROM ERN OK THROUGH PORTIONS AR/MO/SRN IL/WRN KY/WRN

TN...WITH 0-1 KM SRH 250-400 J/KG UNDER 45-60 KT LLJ.

MEANWHILE...60S F SFC DEW POINTS SHOULD BECOME COMMON OVER MOIST

SECTOR AND S OF ABOUT I-70 OVERNIGHT...CONTRIBUTING TO SFC-BASED

PARCELS WITH MLCAPE IN 500-1500 J/KG RANGE.

THOUGH SUBSTANTIAL SVR OUTBREAK IS POSSIBLE...A FEW FACTORS PRECLUDE

MORE SPECIFIC CORRIDOR OF GREATER PROBABILITIES ATTM. IN ADDITION

TO TIMING/LOCATION OF INITIATION...EVOLUTION OF CONVECTIVE MODE

REMAINS HIGHLY UNCLEAR THIS FAR IN ADVANCE. ANY RELATIVELY DISCRETE

SUPERCELLS THAT CAN FORM IN SUCH FAST AMBIENT FLOW MAY TRAVEL LONG

DISTANCES WITH TORNADO POTENTIAL...WHILE DAMAGING QLCS DEVELOPMENT

WITH BOWS/LEWPS APPEARS LIKELY AT SOME POINT OVERNIGHT. SWD

BACKBUILDING OF OVERNIGHT CONVECTION ALSO IS LIKELY...AFFECTING

LOWER MS VALLEY REGION...THOUGH CAPPING WILL MAKE THIS RISK MORE

CONDITIONAL WITH SWD EXTENT TOWARD GULF.

..EDWARDS.. 02/26/2011

[Hoosier]

[Thundersnow12]

Day 2 written by one of the best..

any discrete storm after dark is going to be very dangerous.

[Stebo]

I am starting to wonder if the main show won't hold off until Monday.