18-20 March 2012 severe prospects

[andyhb]

...Keep in mind that's the GFS and its already showing over 1000 J/kg CAPE. LCL looks quite manageable as well. This should also become more impressive as the LLJ strengthens later in the evening.

[Buckeye05]

Winds still looking meridional. Looking like this might line out pretty quickly.

[tornadotony]

The NAM is failing, as suspected. From 21z to 00z Sunday evening, it has 4mb pressure falls over the eastern TX panhandle. Yet, it only has SSE sfc winds, which allows for increased mixing and higher LCL heights. Can't say I would favor that solution.

[andyhb]

The NAM is failing, as suspected. From 21z to 00z Sunday evening, it has 4mb pressure falls over the eastern TX panhandle. Yet, it only has SSE sfc winds, which allows for increased mixing and higher LCL heights. Can't say I would favor that solution.

That doesn't make sense at all, I mean 4 mb in 3 hours...there would have to be more of a LL wind response than that.

[andyhb]

00z GFS is definitely broader at the base of the trough at 48 hrs compared to the 12z at 60 hrs.

Nice hodographs showing up in the butter zone Tony highlighted and will likely grow larger as the LLJ intensifies...juxtaposed with >1000 J/kg CAPE (which I think is underdone) and manageable LCL heights.

Monday looks pretty similar to previous runs of the GFS.

[chase_stormz]

I really feel like Monday has the potential to be the bigger day as the trough speeds up. However, rain/clouds in the warm sector could really calm the potential there. I hate making these decisions when I have to make a 10 hour drive to chase. The tornado threat really will all depend on destabilization when it is all said and done.

[andyhb]

I really feel like Monday has the potential to be the bigger day as the trough speeds up. However, rain/clouds in the warm sector could really calm the potential there. I hate making these decisions when I have to make a 10 hour drive to chase. The tornado threat really will all depend on destabilization when it is all said and done.

One thing, previous convection may not be a lot of an issue further south, as storms will tend to move more north than east in this flow regime, and out of the warm sector.

[chase_stormz]

One thing, previous convection may not be a lot of an issue further south, as storms will tend to move more north than east in this flow regime, and out of the warm sector.

that's a good point. honestly, i feel like as of right now, we need to be in north texas. this system has so much potential. i'd hate to see it go to waste. also, i have heard that the ecm was showing some secondary low development on monday? is this still the case? i have yet to have had a chance to look.

[andyhb]

Day 2, still not mentioning tornadoes, something tells me they may have favored the NAM with this outlook, especially with the low level wind response, I highlighted the portion where this seems evident. Given the height falls on both of the models, I'm not so sure that if we get supercells, which the outlook suggests, that they wouldn't end up becoming tornadic at some point, particularly between 00z and 06z as LCL heights lower and the LLJ intensifies substantially:

DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1258 AM CDT SAT MAR 17 2012

VALID 181200Z - 191200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CENTRAL AND

SRN PLAINS...

..SYNOPSIS

WHILE LARGE-SCALE RIDGING ALOFT PREVAILS ACROSS THE ERN HALF OF THE

CONUS...A STRONG/EXPANSIVE TROUGH AFFECTING MOST OF WRN NOAM WILL

ADVANCE SLOWLY EWD ACROSS THE GREAT BASIN AND INTERMOUNTAIN WEST

THIS PERIOD. WHILE REMAINING OVER THE ROCKIES THROUGH THE

PERIOD...HEIGHT FALLS ASSOCIATED WITH THIS SYSTEM WILL BEGIN

OVERSPREADING THE PLAINS THIS PERIOD...SUPPORTING EVENTUAL

DEVELOPMENT OF STRONG/SEVERE CONVECTION E OF THE MOUNTAINS.

AT THE SURFACE...A CONSOLIDATING/STRENGTHENING LOW SHOULD MOVE NEWD

WITH TIME REACHING THE WRN ND VICINITY LATE. A TRAILING N-S COLD

FRONT IS EXPECTED TO MOVE INTO THE HIGH PLAINS DURING THE SECOND

HALF OF THE PERIOD...BUT A PRIMARY FOCUS OF THE MORE ROBUST

CONVECTIVE ACTIVITY WILL LIKELY BE A DRYLINE EXPECTED ACROSS THE

CENTRAL/SRN HIGH PLAINS DURING THE AFTERNOON.

..CENTRAL AND SRN PLAINS

SHOWERS AND THUNDERSTORMS -- LIKELY HIGH-BASED -- ARE FORECAST TO

DEVELOP DURING THE AFTERNOON ATOP A CAPPED BOUNDARY LAYER OVER THE

SRN PLAINS...AS A LEAD WAVE SHIFTS ACROSS THE REGION IN ADVANCE OF

THE LARGER-SCALE SYSTEM. ATTM...IT APPEARS THAT LITTLE IF ANY

SEVERE THREAT WILL ACCOMPANY THIS CONVECTION...AS IT SPREADS ACROSS

PARTS OF CENTRAL AND E TX/OK/KS AND INTO MO/AR THROUGH THE AFTERNOON

AND EVENING.

MEANWHILE...A MORE POTENT SEVERE WEATHER ENVIRONMENT SHOULD BE

EVOLVING ACROSS THE CENTRAL AND SRN HIGH PLAINS...AS HEATING AHEAD

OF A SURFACE DRYLINE RESULTS IN MODERATE DESTABILIZATION. AS HEIGHT

FALLS SPREAD SLOWLY EWD ATOP THE DRYLINE...INCREASING ASCENT --

FOCUSED ALONG THE SURFACE BOUNDARY -- SHOULD RESULT IN

ISOLATED/AFTERNOON STORM DEVELOPMENT. WITH TIME...COVERAGE OF

CONVECTION SHOULD INCREASE -- PARTICULARLY THROUGH THE EVENING AS

SLIGHT NEGATIVE TILTING OF THE MAIN UPPER TROUGH RESULTS IN STRONGER

ASCENT OVERSPREADING THE AREA AFTER DARK.

AS THE SYSTEM SHIFTS EWD...FLOW ALOFT WILL CONTINUE TO INCREASE.

WHILE INCREASINGLY MERIDIONAL WITH NWD EXTENT...SSWLY FLOW AT MID

LEVELS FROM ROUGHLY KS SWD ATOP SSELY BOUNDARY LAYER FLOW AHEAD OF

THE DRYLINE WILL RESULT IN A FAVORABLY-SHEARED

ENVIRONMENT...SUPPORTIVE OF RAPIDLY STRENGTHENING SUPERCELL STORMS.

WHILE ISOLATED INITIALLY...THE RELATIVELY NARROW CORRIDOR OF

GREATEST THREAT SUPPORTS MAINTENANCE OF A HIGHER-END SLIGHT RISK --

WITH VERY LARGE HAIL AND LOCALLY DAMAGING WINDS THE MAIN THREATS.

..GOSS.. 03/17/2012

[brettjrob]

Sunday still strikes me as one of the more difficult Plains convective forecasts in quite awhile, especially WRT tornado potential. There are now several issues and potential drawbacks working against significant tornadic supercells, and yet you can't ignore the classic first several km AGL of the hodos. None of the drawbacks seem like complete dealbreakers, yet. And if one or two of those issues trend the right way tomorrow, we could still have a significant event.

The most interesting and potentially crucial piece of the puzzle on today and tonight's model runs is the subtle shortwave forecast to ride NE over the dryline in the morning hours. Several models now forecast precipitation with that wave, which would clearly inhibit instability. The degree to which instability right along the dryline would be hurt come late afternoon and early evening is a big question, though, and one likely not well-handled by models relying on convective paramaterization. Also, ironically, one effect of that early cloudcover and precipitation is to keep LCLs much more favorable on some model soundings. Is it possible that the lead wave could lower LCLs some while still not hurting instability enough to prevent vigorous surface-based DMC later in the day? Impossible to say from two days out, obviously. I don't envy SPC right now. (Though, having said that, I'm still a little surprised that the T-word wasn't even mentioned once in the discussion).

[andyhb]

What I find weird is that they mentioned supercells (and rapidly intensifying ones at that), and given the LCL heights lowering eventually and LL moisture remaining adequate, those supercells will probably have at least some tornado potential, considering the fact that the LL wind response may be underdone by some of the models. The fact that they mention convection/supercells initiating, makes me think they may be looking for problems more in the kinematics rather than the thermodynamics.

Honestly, I find that discussion somewhat confusing, to be honest.

[andyhb]

Day 3, no mention of tornadoes either (this tells me they may be favoring the NAM, considering they mentioned tornadoes yesterday in the Day 4 when the NAM was out of range), but on the 06z NAM, I'm beginning to see some more favorable shear profiles develop along the I-35 corridor (essentially where the outlook marks the sig-severe) in TX and OK after 18z, which obviously includes some very highly populated areas:

DAY 3 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0211 AM CDT SAT MAR 17 2012

VALID 191200Z - 201200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MN VICINITY SSWWD INTO

THE LOWER RIO GRANDE VALLEY...

...SYNOPSIS...

HIGHLY-AMPLIFIED FLOW FIELD ALOFT IS FORECAST THIS PERIOD...AS A

LARGE/FAIRLY SHORT WAVELENGTH TROUGH CONTINUES A SLOW EWD SHIFT

TOWARD THE CENTRAL U.S. WHILE A STRONG/LARGE-SCALE RIDGE PREVAILS

ACROSS THE ENTIRE ERN CONUS.

AT THE SURFACE...HIGH PRESSURE IS FORECAST ACROSS BOTH THE WRN AND

ERN THIRDS OF THE COUNTRY...WHILE THE CENTRAL U.S. EXPERIENCES THE

EFFECTS OF A SLOWLY ADVANCING COLD FRONT. THIS FRONT WILL FOCUS THE

PRIMARY AREA OF STRONG/POTENTIALLY SEVERE CONVECTION THIS PERIOD.

...ERN HALF OF THE PLAINS AND INTO THE MID MO VALLEY/OZARKS...

COMPLEX/CHALLENGING WEATHER SCENARIO IS UNFOLDING THIS PERIOD...AS

CONTINUED/SLOW EWD ADVANCE OF THE LARGE STORM SYSTEM INTO THE PLAINS

IS EXPECTED. ONGOING SHOWERS AND STORMS -- AND POSSIBLY SOME SEVERE

POTENTIAL -- ARE EXPECTED AT THE START OF THE PERIOD...WHICH --

ALONG WITH ASSOCIATED CLOUD COVER AND GENERAL SLOW MOVEMENT OF THE

PRECIPITATION -- WILL LIKELY HINDER DESTABILIZATION POTENTIAL ACROSS

A LARGE PORTION OF THE POTENTIAL THREAT AREA.

ATTM...IT APPEARS THAT A BROAD ZONE OF RISK FOR SEVERE STORMS WILL

EXIST AHEAD OF THE COLD FRONT AS IT ADVANCES ACROSS THE

PLAINS...WITH AT LEAST SOME THREAT EXTENDING FROM NRN MN SWD TO THE

LOWER RIO GRANDE VALLEY. THOUGH INSTABILITY SHOULD REMAIN FAIRLY

LIMITED ACROSS MUCH OF THE AREA FROM ERN OK NWD...FAVORABLE SHEAR

AND FAIRLY STRONG LOW-LEVEL FORCING SHOULD SUPPORT VIGOROUS STORMS

CAPABLE OF PRODUCING LOCALLY DAMAGING WINDS AND HAIL.

THE GREATEST THREAT ATTM APPEARS TO EXIST FROM ERN OK AND PERHAPS

WRN AR SSWWD ACROSS PARTS OF CENTRAL AND ERN TX -- ROUGHLY ALONG THE

I-35 CORRIDOR. HERE...GREATER DESTABILIZATION POTENTIAL IS EVIDENT

ALONG THE SERN FRINGE OF ONGOING STORMS. THIS COMBINED WITH

SLIGHTLY MORE SWLY COMPONENT TO THE FLOW ALOFT YIELDING A MORE

FAVORABLE WIND PROFILE SUGGESTS A FOCUSED AREA OF GREATER SEVERE

POTENTIAL -- REFLECTED IN THE OUTLOOK GRAPHIC.

MODELS ARE FAIRLY CONSISTENT IN DEVELOPING A MORE LINEAR/SLOW-MOVING

BAND OF CONVECTION FROM SWRN MO/ERN OK/WRN AR SWWD TO THE LOWER RIO

GRANDE VALLEY THROUGH THE EVENING AND INTO THE OVERNIGHT HOURS ALONG

THE ADVANCING FRONT. ALONG WITH ONGOING SEVERE RISK...POTENTIAL FOR

LOCALLY VERY HEAVY RAINFALL ALSO APPEARS TO EXIST.

..GOSS.. 03/17/2012

[Paul_Carlone]

The good thing about this storm is the novice and uneducated (SPC chasers) will be sitting this one out. Hodos like that with the likelihood for substantial instability and LCLs that look just fine for me considering this is the high plains mean IMPO that at least one cell will produce. There will be microscale/small scale mesoscale processes that models just cant pick up. If that convection occurs there will be outflow boundaries and the possibility for decreased LCLs (evaporation from early precip lowering DP/T spread) with still substantial instability.

Iv read numerous case studies and witnessed events in the high plains where LCLs of 2000m+ produced tornadoes or funnels. With this event (TX/OK pans into W.KS) you have what looks like a LCL precentile chance of:

5%: sub 750m

15%: 750-1000m

25%:1000-1250m:

40%: 1250-1500m

15%: 1500m+

(Disclaimer: Despite years and years of math I have been known to have my percentages not equal 100%)

With the lower LCLs more likely in areas of higher evaporation (from morning precip), moisture convergence due to surface confluence and other factors (not sure how intense this will be but it occurs with every event some areas have better surface moisture convergence), there are many other small factors that could affect LCLs but I dont believe they are as important as the first two.

I have seen others posting about lack of LL shear and models underpredicting it which I agree with completely. Models always seem to underestimate the LL shear and often the CAPE in these situations. With the pressure falls expected winds would most likely come roaring out of the SE instead of trickling out of the S or SSE. My major concerns revolve around the accuracy of the models at this point. I think this is a smell the air and chase with the brain chase for anyone who wants to go.

I hope my 1st post wasnt a rambling mess I swear im not an idiot haha

[JoMo]

12z NAM would indicate SE OK on Monday afternoon/evening as it has a great backing of the winds showing up and EHI. However, convective evolution is a mess with this entire system.

[Thundersnow12]

The good thing about this storm is the novice and uneducated (SPC chasers) will be sitting this one out.

I'd disagree, I find that more dumb chasers will chase more setups including bad ones, where the ole veterans, better chasers will tend to pick and choose.

[Paul_Carlone]

I'd disagree, I find that more dumb chasers will chase more setups including bad ones, where the ole veterans, better chasers will tend to pick and choose.

I guess it all depends. The best chasers are always out, the smartest chasers are out only on the days that have sig potential to produce tornadoes, the novices tend to follow what SPC, Forbes, or Timmer say or look at one thing on one model. Tomarrow looks like one of those days where the novices with a 6+ hr drive will let someone talk them into staying home. The novices in the area will be out but so will everyone in the area.

Most novices or those with lacking forecasting skills immediatly jump to "well the SPC says" instead of realizing that the SPC is forecasting for the general public over a broad area not for storm chasers finding the right SUP in the right environment. Then again I have heard it is OU's spring break so who knows how many of the amatures from there will be out. (not an OU bash just saying they have one of the largest meteorology programs so probally a lot of young chasers)

[Jim Martin]

Looking like east Texas is going to be the hot spot for potential tornadic activity on Monday. Based off of the 09z SPC SREF.

[Jim Martin]

[Thundersnow12]

DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1230 PM CDT SAT MAR 17 2012

VALID 181200Z - 191200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN AND

CENTRAL PLAINS...

..SYNOPSIS

LARGE-SCALE RIDGING ALOFT...WITH SOME STRENGTHENING...WILL PREVAIL

ACROSS THE ERN HALF OF THE CONUS ON SUNDAY...AS A STRONG/EXPANSIVE

TROUGH AFFECTING MOST OF WRN NOAM WILL ADVANCE SLOWLY EWD ACROSS THE

GREAT BASIN AND INTERMOUNTAIN WEST. HEIGHT FALLS ASSOCIATED WITH

THIS SYSTEM WILL BEGIN OVERSPREADING THE PLAINS...SUPPORTING

EVENTUAL DEVELOPMENT OF STRONG/SEVERE CONVECTION E OF THE MOUNTAINS.

MEANWHILE...A WEAKER MIDLEVEL SHORTWAVE TROUGH/SPEED MAX EMBEDDED

WITHIN A SUBTROPICAL JET EMANATING FROM SW OF BAJA IS EXPECTED TO

TRACK NEWD FROM SW TX THROUGH OK/KS AND REACH THE UPPER MS VALLEY BY

LATE SUNDAY NIGHT/EARLY MONDAY MORNING.

AT THE SURFACE...A CONSOLIDATING/STRENGTHENING LOW SHOULD MOVE NEWD

REACHING WRN ND LATE. A TRAILING N-S COLD FRONT WILL MOVE INTO THE

HIGH PLAINS DURING THE SECOND HALF OF THE PERIOD...BUT THE PRIMARY

FOCUS FOR THE MORE ROBUST CONVECTIVE ACTIVITY WILL BE A DRYLINE

EXPECTED ACROSS THE CENTRAL/SRN HIGH PLAINS DURING THE AFTERNOON.

..CENTRAL AND SRN PLAINS

MODELS CONTINUE TO SUGGEST AN AREA OF SHOWERS AND TSTMS SHOULD

DEVELOP SUNDAY AFTERNOON WELL E OF THE DRY LINE...FROM CENTRAL AND E

TX/OK/KS INTO MO/AR THROUGH THE EVENING...ATTENDANT TO ASCENT WITH

THE SUBTROPICAL SHORTWAVE TROUGH/50 KT SPEED MAX. DESPITE THE LACK

OF MIDLEVEL COOLING...FORECAST SOUNDINGS SUGGEST LOW LEVEL

MOISTENING AND SOME SURFACE HEATING WILL PROVE SUFFICIENT TO WEAKEN

A CAP OVER THE ERN PORTION OF THE SRN/CENTRAL PLAINS FOR TSTM

DEVELOPMENT. MARGINAL INSTABILITY /MLCAPE OF 500-1000 J PER KG/ AND

STRENGTHENING BULK SHEAR PER 50 KT MIDLEVEL JET SUGGEST AN ISOLATED

THREAT FOR STRONG TO SEVERE STORMS WILL BE POSSIBLE OVER CENTRAL/E

TX THROUGH OK TO CENTRAL/ERN KS. LOW SEVERE WEATHER PROBABILITIES

HAVE BEEN EXPANDED EWD SOME TO ACCOUNT FOR A GREATER AREAL COVERAGE

OF THIS LOW END SEVERE THREAT.

MEANWHILE...MODELS CONTINUE TO INDICATE A MORE POTENT SEVERE WEATHER

ENVIRONMENT SHOULD BE EVOLVING ACROSS THE CENTRAL AND SRN HIGH

PLAINS SUNDAY AFTERNOON...AS HEATING ALONG AND AHEAD OF THE DRYLINE

RESULTS IN MODERATE DESTABILIZATION. BY 18/21Z-19/00Z...THE DRY LINE

SHOULD EXTEND FROM CENTRAL NEB THROUGH THE ERN EXTENT OF THE TX

PANHANDLE TO SWRN TX /INVOF VAL VERDE COUNTY/. HEIGHT FALLS

SPREADING SLOWLY EWD ATOP THE DRYLINE WILL SUPPORT INCREASING

ASCENT FOCUSED ALONG THIS BOUNDARY RESULTING IN AFTERNOON STORM

DEVELOPMENT...POTENTIALLY BY 18/21Z...FROM W TX TO WRN KS. WITH

TIME...COVERAGE OF CONVECTION SHOULD INCREASE...PARTICULARLY THROUGH

THE EVENING AS GREATER HEIGHT FALLS/STRONGER ASCENT OVERSPREAD THE

SRN HIGH PLAINS AFTER DARK.

AS THE SYSTEM SHIFTS EWD...FLOW ALOFT WILL CONTINUE TO STRENGTHEN

AND BECOME INCREASINGLY MERIDIONAL WITH NWD EXTENT. S/SWLY FLOW AT

MID LEVELS FROM KS SWD ATOP SSELY BOUNDARY LAYER FLOW AHEAD OF THE

DRYLINE WILL RESULT IN A FAVORABLY-SHEARED ENVIRONMENT...SUPPORTIVE

OF RAPIDLY STRENGTHENING SUPERCELL STORMS. TORNADOES AND HAIL...SOME

VERY LARGE...WILL BE ATTENDANT TO THE INITIAL...MORE DISCRETE...

STORMS. THESE THREATS COMBINED WITH A CONTINUED SEVERE WEATHER

THREAT AS ACTIVITY EVOLVES AFTER DARK INTO A MORE LINEAR MODE

MAINTAINS A RELATIVELY NARROW CORRIDOR OF A HIGHER-END SLIGHT RISK.

[tornadotony]

12z runs definitely uptick the threat a bit overall, especially Monday. Monday might go gangbusters in the heart of Texas.

[andyhb]

12z runs definitely uptick the threat a bit overall, especially Monday. Monday might go gangbusters in the heart of Texas.

I definitely have concerns about a lot of the highly populated areas in Central and Eastern Texas

[brettjrob]

I'd all but written Monday off over the past several days, but I'm starting to get more impressed with central TX. The scope of any potential significant event will certainly be limited by ongoing early convection for areas near and N of I-20, plus extreme backing of upper flow. However, there appears to be a sweet spot roughly from Waco to Austin to College Station where moderate instability, a strong LLJ, and good directional shear may overlap; plus, this area may be far enough south to avoid convective vomit early in the day. Need to get through tomorrow first before pinning down detailed locations and the magnitude of the threat, though.

[andyhb]

Right now, I think the greatest risk for tornadic supercells Monday is in that sweet spot Brett mentioned (perhaps expanded to also include San Antonio and Houston) and then eastward into the SE Texas, Western LA and the Arklatex. I saw a graphic on SHV's website where there was some really impressive turning with height on the cross over across the entire area by 7 pm Monday (90° or greater with upper level winds out of the WSW/SW and surface winds backed SSE to SE), juxtaposed with greater than 1000 J/kg of CAPE. Note that this also on the southern end of the front/dryline, where the most instability will tend to build up and also where prior convective junk will tend to have the least influence, with the former area being far enough south and the latter far enough east. Given the increasing dynamic forcing and shear vectors favorably aligned with the incoming front, I think there is a real possibility we could see clusters of supercells in this area, prior to the line making it there, especially as the LLJ strengthens.

It looks like the NAM is still underestimating the wind response to height falls WRT Sunday's threat, which appears to getting more favorable for discrete supercells with each model run, especially on the GFS...

[andyhb]

Here's that aforementioned graphic, note the cross over profiles (the CAPE near SHV is about 1000 J/kg, and then near San Antonio in that yellowish area it is nearly 3000 J/kg). Also note the winds profile in the areas of highest instability, good lord (and that is without veer-back-veer):

[brettjrob]

Hodos like these are why I still feel decent about the potential for a significant tornado event across the eastern Panhandles into SW KS. Needless to say, the LCLs would be a problem if you took this sounding verbatim. However, there's better moisture in place just E of this site in the model solution with similar hodos. If you account for surface winds backing a tad more than shown here and then consider probable soundings along the eastern column of PH counties, it's not hard to imagine this event shaping up more like some of the impressive early-season 2007 events in that area.

18Z NAM rolling in looks to further improve low-level moisture closer to the dryline, FWIW.

[andyhb]

Classic sickle shaped hodograph there...

18z NAM verifies and we have big problems on Monday in that area that I mentioned earlier, is now taking a much more GFS-esque solution...

[chase_stormz]

Classic sickle shaped hodograph there...

18z NAM verifies and we have big problems on Monday in that area that I mentioned earlier, is now taking a much more GFS-esque solution...

I agree. That sweet spot mentioned earlier from Waco, to Austin, to College Station looking scary based off the 18z NAM. Definitely a strong tornado risk. Hodos look really nice.

[thewxmann]

I, too, am beginning to think that if anything will happen, it will be in ctrl-srn TX. Models are painting the development of a development of a secondary low in that area along with a mini-dryline. The area near the "triple point" and on the edge of the steepest low-lvl lapse rates, in a corridor from Del Rio-San Antonio-Houston, looks somewhat interesting.

[chase_stormz]

Scary hodo near Lampasas, TX Monday evening per the 18z Nam

[Minnesota Meso]

My thoughts for day three, (Monday.) Here in Minnesota according to the nam we could have a low cape high sheer event, ie cape around 750 or so, with 0-1 km sheer around 20 knts, and 0-6 around 40, soundings show this to be all unidirectional. The Euro however has been very consistant with almost no cape at all, at best 200, as the 850-700mb layer shows high RH values around 70-80., By Monday morning we should be trapped under a pretty good cloud deck. The Nam shows some sun, but I don't trust it. Therefore I don't think the SPC's current day 3 (monday) forecast of a 15% chance of severe will verify, more like a 5% chance.

Moving on to TX and OK, here is where I think the Nam does the best job, ie closest to where severe will be. I too agree that a big threat is working towards central to north central Tx Monday evening, cape values are high and the sheer profiles are quite impressive just ahead of the dry line at 21z Mon thru 03z Tues. Precip values are rather low at around .25 to .50 suggesting that any super cells would be LP in nature (a storm chasher's dream). I think chances for EF2 to a EF4 are quite high at this time. I think we have all have seen the crossover winds.

The overnight hours have me really concerned for TX.. as the storms become more linear , the sheer values seem to increase, so using Minnesota lingo, look out for top side Lena and tail end Ole, as well as midsection Lena/Ole, any cells that can seperate themselves from the line could produce a night time tornado.

Stay safe everyone!!

BTW the Nam is just lousy during the cold season, I very seldom look at it, and when I do, I get a good laugh!!! LOL

PS: I still think the SE OK is under the gun as well