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Not to get ahead of myself, but the 00z GFS looks awfully favorable in KS on Sunday, perhaps OK as well although capping may be a bit more of an issue down there. The wind fields in KS now look just as favorable as further south with a even a bit more instability thanks to the mid level cold pocket overlapping more of the warm sector.

 

Not to mention the fact that Monday continues to hold potential further east and for perhaps another round in the Plains with the second jet streak.

 

Pretty nice run overall so far. Never really clears the moisture, partly because the 500 low closes off pretty far west and then washes out fairly quick. That next trough starts crashing in pretty hard initially...

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Congrats to everyone for the great catches today near and S of I-20. I was lazy and looked ahead to the weekend too much, trying to get some work done before leaving here around 4pm. Think I got a rain-wrapped tornado near Alvord (Wise Co.) but it pales to the southern activity, of course. Unfortunate to hear of the severe impacts of the Hood Co. storm, though.

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GFS looks simply amazing for much of central OK/KS on Sunday, but seems to be the outlier in terms of a slower and more amplified solution. None of the foreign models look as impressive, but for the most part, a notable tornadic supercell threat is still present somewhere.

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GFS looks simply amazing for much of central OK/KS on Sunday, but seems to be the outlier in terms of a slower and more amplified solution. None of the foreign models look as impressive, but for the most part, a notable tornadic supercell threat is still present somewhere.

 

Yeah the Euro is a bit quicker but still doesn't look benign at all with a solid mid-level speed max punching right over the warm sector on Sunday (with the second jet streak coming in for Monday/Tuesday), the LLJ is a bit more veered (on Sunday), but it still looks manageable, tbh the main difference at this time appears to be more speed and less amplitude, the GFS and Euro are basically lock step with 500 mb amplitude at 72 hrs (if you look at the ejection across the Four Corners) except the Euro is a bit faster.

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Oh, and a bit off-topic, but what is with this nonsense on TWC's website in the "Top Stories" department when there has been a deadly tornado this evening and there is nothing on the front page that indicates this at all.

 

"Worst Food at Restaurants"

 

"Stinky Corpse Flower Blooms Again"

 

"Bye Bye Bunnies"

 

"Wind Farms Get Pass On Eagle Deaths"

 

http://www.weather.com/

 

/rant

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By the way, D3 is out, it is a 30% sig-hatched primarily for Central SD while the hatched area extends southward into North-Central NE. Storm coverage (understandably) in question further south.

 

MqUVSiI.gif

DAY 3 CONVECTIVE OUTLOOK     NWS STORM PREDICTION CENTER NORMAN OK   0230 AM CDT THU MAY 16 2013      VALID 181200Z - 191200Z      ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE NRN PLAINS REGINO SWD   INTO PARTS OF KS...      ...SYNOPSIS...   PROGRESSION OF THE AMPLIFIED UPPER FLOW FIELD ACROSS THE U.S. IS   FORECAST THIS PERIOD...AS A LARGE TROUGH OVER THE INTERMOUNTAIN WEST   ADVANCES EWD AND BEGINS AFFECTING THE PLAINS.  AS THIS OCCURS...A   TROUGH IN LEE OF THE ROCKIES IS FORECAST TO SHIFT EWD WITH TIME INTO   THE PLAINS...SERVING AS A FOCUS FOR STRONG/SEVERE THUNDERSTORM   DEVELOPMENT DURING THE LATE AFTERNOON AND EVENING.      ...NRN AND CENTRAL PLAINS...   AS THE SHARP UPPER RIDGE OVER THE PLAINS GRADUALLY GIVES WAY TO   FALLING MID-LEVEL HEIGHTS AHEAD OF THE ADVANCING   TROUGH...LARGE-SCALE ASCENT WILL ATTEMPT TO ERODE A VERY STOUT   CAPPING INVERSION.  AS DIURNAL HEATING CONTRIBUTES TO MODERATE CAPE   DEVELOPMENT ATOP THE CAP...THREAT FOR SEVERE STORMS WILL GRADUALLY   INCREASE THROUGH THE MID TO LATE AFTERNOON HOURS.  INITIAL   CONVECTION WILL LIKELY OCCUR OVER THE HIGHER TERRAIN OF THE HIGH   PLAINS VICINITY...THOUGH WEAKER CAPE IN THIS PART OF THE AREA   SUGGESTS ONLY LOW-PROBABILITY POTENTIAL FOR DAMAGING WINDS AND HAIL.      HOWEVER...AS SURFACE TROUGHING SHIFTS EWD INTO THE PLAINS WITH TIME   AND LARGE-SCALE ASCENT PERSISTS...EXPECT SCATTERED STORM DEVELOPMENT   TO OCCUR BY LATE AFTERNOON AND INTO EARLY EVENING -- PARTICULARLY   FROM SRN ND SWD ACROSS SD.  WHILE SSWLY FLOW AT MID LEVELS WILL   LIMIT OVERALL SHEAR TO SOME DEGREE...PROFILES WILL SUPPORT   ORGANIZED/SUPERCELL STORMS CAPABLE OF PRODUCING VERY LARGE HAIL AND   DAMAGING WINDS.  A COUPLE OF TORNADOES WILL ALSO BE POSSIBLE...MOST   LIKELY NEAR AND NE OF A WEAK SURFACE LOW PROGGED TO EXIST OVER SD.           THREAT SHOULD CONTINUE INTO THE EVENING...SHIFTING SLOWLY EWD BEFORE   GRADUALLY DIMINISHING WITH TIME INTO THE OVERNIGHT HOURS.      ...SRN PLAINS...   A CAPPED BOUNDARY LAYER DURING THE MORNING AND EARLY AFTERNOON   SHOULD GIVE WAY TO A DEEPLY MIXED LOWER TROPOSPHERE BY LATE   AFTERNOON...ALONG A DRYLINE WHICH SHOULD EXTEND SWD ACROSS WRN OK   AND INTO PORTIONS OF CENTRAL TX E OF THE S PLAINS/TRANSPECOS REGION.      ISOLATED STORMS ARE FORECAST ALONG THE DRYLINE WHERE THE CAP CAN   WEAKEN SUFFICIENTLY...BUT MARGINAL SHEAR IS EXPECTED THROUGH THE   AFTERNOON ATOP THE DRYLINE SUGGESTING LIMITED SEVERE THREAT.  THE   DRY/DEEP BOUNDARY LAYER COULD AID IN DEVELOPMENT OF LOCALLY   STRONG/DAMAGING WINDS...AND HAIL COULD ALSO OCCUR WITHIN THE   STRONGER CELLS.  HOWEVER...POTENTIAL COVERAGE OF CONVECTION IS IN   QUESTION ATTM...AND THUS WILL INTRODUCE ONLY LOW /5%/ SEVERE   PROBABILITY ATTM.  A STORM OR TWO MAY LINGER INTO THE EVENING...BUT   EXPECT RE-ESTABLISHMENT OF THE CAP DURING THE EVENING TO RESULT IN A   SLOW DECREASE IN CONVECTION.      ..GOSS.. 05/16/2013
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Day 4 and 5 have grown in size for the region.

 

day48prob.gif

 

 

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0349 AM CDT THU MAY 16 2013

VALID 191200Z - 241200Z

...DISCUSSION...
MEDIUM-RANGE MODELS REMAIN IN BROAD/GENERAL AGREEMENT THAT
SUBSTANTIAL SEVERE WEATHER POTENTIAL EXISTS DAYS 4-5 /SUN. 5-19 AND
MON. 5-20/ AND POSSIBLY INTO DAY 6. HOWEVER...RATHER PRONOUNCED
DIFFERENCES IN TIMING/LOCATION OF SHORT-WAVE FEATURES CASTS
SUBSTANTIAL UNCERTAINTY REGARDING DETAILS OF THE UPCOMING SCENARIO.

IN GENERAL...THE TROUGH SHIFTING INTO THE PLAINS AT THE START OF THE
PERIOD IS FORECAST TO PROGRESS EWD IN A SOMEWHAT PIECEMEAL FASHION.
THE INITIAL/ENERGETIC SHORT-WAVE FEATURE SHOULD AFFECT THE CENTRAL
PLAINS SUNDAY...WITH RELATIVELY WIDESPREAD STORM DEVELOPMENT LIKELY
TO OCCUR ALONG A ROUGHLY N-S SURFACE BOUNDARY OVER THE CENTRAL
PLAINS REGION AS THE AIRMASS BECOMES MODERATELY TO STRONGLY UNSTABLE
DURING THE AFTERNOON. WITH 40 TO 50 KT SWLY MID-LEVEL FLOW ATOP
STRONG LOW-LEVEL SLYS...DEGREE OF SHEAR WILL COMBINE WITH THE VERY
FAVORABLE BUOYANCY TO ALLOW STORMS TO QUICKLY BECOME
SEVERE/SUPERCELLULAR...WITH VERY LARGE HAIL AND DAMAGING WINDS
EXPECTED ALONG WITH ISOLATED TORNADOES. SEVERE THREAT SHOULD
CONTINUE WELL INTO THE EVENING HOURS...THOUGH LIKELY DIMINISHING
SOMEWHAT OVERNIGHT.

MONDAY...WITH AN UPPER LOW FORECAST TO HAVE EVOLVED OVER THE NRN
PLAINS...A SECOND SHORTER-WAVELENGTH TROUGH IS PROGGED TO ROTATE
SEWD OUT OF THE ROCKIES AND INTO THE CENTRAL PLAINS REGION.
AGAIN...TIMING AND LOCATION OF THIS FEATURE DIFFERS AMONGST THE
VARIOUS MODELS...AND CONVECTION FROM SUNDAY WILL LIKELY HAVE
INFLUENCED THE SURFACE PATTERN SUBSTANTIALLY -- BOTH OF THESE
FACTORS YIELDING UNCERTAINTY WITH REGARDS TO THE SEVERE WEATHER
FORECAST. STILL...MODERATE TO STRONG INSTABILITY AND EMERGENCE OF
THIS SECOND/STRONGER SWLY MID-LEVEL JET STREAK SUGGESTS THREAT FOR
VERY LARGE HAIL...DAMAGING WINDS...AND TORNADOES AS AFTERNOON STORMS
ERUPT ACROSS THE MID MS/LOWER MO VALLEYS AND INTO PARTS OF KS/OK/N
TX AND POSSIBLY NWRN AR.

MODEL DIFFERENCES CONTINUE TO INCREASE INTO DAY 6 /TUESDAY/...WHICH
-- COMBINED WITH THE TWO PRIOR DAYS OF WHAT WILL LIKELY HAVE BEEN
WIDESPREAD CENTRAL U.S. CONVECTION/SEVERE WEATHER -- CASTS ENOUGH
UNCERTAINTY INTO THE FORECAST SUCH THAT NO AREAL DELINEATION OF
THREAT WILL BE INCLUDED ATTM BEYOND DAY 5. STILL...TUESDAY SEVERE
POTENTIAL WILL REQUIRE RE-EXAMINATION IN LATER OUTLOOKS AS AMPLE
SHEAR AND INSTABILITY FOR CONTINUED SEVERE POTENTIAL WILL LIKELY
EXIST.

 

 

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Oh, and a bit off-topic, but what is with this nonsense on TWC's website in the "Top Stories" department when there has been a deadly tornado this evening and there is nothing on the front page that indicates this at all.

/rant

I just went through some other main news sites... CNN, Fox, BBC, and Accuweather all have mentions of Texas tornadoes on the home page. TWC does not.

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I just went through some other main news sites... CNN, Fox, BBC, and Accuweather all have mentions of Texas tornadoes on the home page. TWC does not.

 

Sad, that's all that can be said.

 

Also, here's your dandy sounding of the day, from Ft. Worth at 00z, note the SBLCL, ESRH, CAPE, CIN, SCP, crossover, etc.

 

FWD.gif

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I just went through some other main news sites... CNN, Fox, BBC, and Accuweather all have mentions of Texas tornadoes on the home page. TWC does not.

 

Honestly that is mystifying, you are the WEATHER channel, who the hell are you trying to appeal to when you don't even talk about the tornadoes that hit in the last 12 hours.

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Honestly that is mystifying, you are the WEATHER channel, who the hell are you trying to appeal to when you don't even talk about the tornadoes that hit in the last 12 hours.

 

It's pretty sad, all I see anymore are ridiculous sensationalist headlines. One recently was "Asteroid Heading Towards Earth? Pray, says NASA." Upon clicking you find out that it's some hypothetical scenario; completely and utterly ridiculous. Not to mention the use of the word outbreak at every opportunity 10 days before a weather event.

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It's pretty sad, all I see anymore are ridiculous sensationalist headlines. One recently was "Asteroid Heading Towards Earth? Pray, says NASA." Upon clicking you find out that it's some hypothetical scenario; completely and utterly ridiculous. Not to mention the use of the word outbreak at every opportunity 10 days before a weather event.

It's disappointing really...every news station is like this though :(

I flipped over to TWC last night for about 10 mins, just in time to hear them discussing Saturday and Sunday where Dr. Forbes was predicting "an outbreak of sorts" and his torcon was already at a 6...with basically NO information to back up the predicition/discussion...may prove a valid prediction but pretty tough to do four and five days out.  Sensationalist TV sells though. 

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Don't let facts get in the way of some good, old fashioned TWC hate  :facepalm:

Sometimes TWC does really good but the last couple years they've really begun to hype EVERYTHING that comes along...I would rather have the information without the hype until you're a day or so out.  But they do have ot make money and if that keeps viewers tuned in, I'd rather have the TWC with a bit of hype than no TWC at all if that makes sense.

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The evolution of the Arlington cell looked really familiar last night. On June 1st, 2011 there was a funnel cloud sighted in my home town with a similar "dangling" pendant style hook.  As the cyclonic circulation tightened at the base of the inflow, rather than seeing the echoes continuing to spiral inward as often witnessed in strong tornadoes, instead there is a doubling back, forming an "S" shaped signature with signs of weak anti-cyclonic rotation just in front.   I'd be interested to hear some thoughts on the mechanics of this if folks have an idea what's going on. 

 

20130515_arl_circ.gif

 

 

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The evolution of the Arlington cell looked really familiar last night. On June 1st, 2011 there was a funnel cloud sighted in my home town with a similar "dangling" pendant style hook.  As the cyclonic circulation tightened at the base of the inflow, rather than seeing the echoes continuing to spiral inward as often witnessed in strong tornadoes, instead there is a doubling back, forming an "S" shaped signature with signs of weak anti-cyclonic rotation just in front.   I'd be interested to hear some thoughts on the mechanics of this if folks have an idea what's going on.

 

Hey, it's great to be talking severe weather with you again! Looking forward to late May-July, as always (let's see if we can get another EML up this way haha).

It is my understanding that there are occasionally 2 RFDs in the process of tornadogenesis with the second usually adding the strongest source of M. These processes were highlighted nicely in the Vortex II / Markowski papers that we discussed last year. Is this what you are referring to or did I miss what you were saying?

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What a day and not how we thought it would evolve. Ended up seeing three tornadoes with the first one near I-20/Weatherford lasting 10-12 minutes. We were further back and had a great view of the tornado as it occluded and got to see the new meso form to its east producing a 2nd smaller, shorter tornado. The 3rd one occured under a low rotating bowl with halfway down cone and several vortices dancing around underneath it. 

 

Ended up having bad road options after this and couldn't keep up with SE moving supercell. 

 

Overnight in SPS.

 

I'm so happy for you! I'm glad things worked out for your chase trip! May 1990 strikes again? lol

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Been proposed that the "S" signature is the RFD coming around the south side of the tornado. It matches up with the idea that the RFD can help give the storm it's final spin to drop the tornado. And what HM said - that was added as I'm typing.

 

Meanwhile the 12Z NAM is in. Fires convection Saturday along an apparent boundary intersecting the DL in KS/OK. That boundary is probably outflow OFB left over from Fri. Suppose it would be there long as LLJ stays decoupled. Mixing down would destroy the OFB. Concerns of a high bases noted that far south where it'll be hot! Otherwise we got the synoptic WF farther north.

 

Sunday looks good with one or more OFBs around plus the WF. Like those days. Multiple targets spreads out chasers. The one DL one WF is where you get 2,000 people on the triple point. Booo! Monday still showing that southern jet max coming out on the south end of everything. I have not looked hard at the synoptic WF and low up north, but not too shabby. Cheers!

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Hey, it's great to be talking severe weather with you again! Looking forward to late May-July, as always (let's see if we can get another EML up this way haha).

It is my understanding that there are occasionally 2 RFDs in the process of tornadogenesis with the second usually adding the strongest source of M. These processes were highlighted nicely in the Vortex II / Markowski papers that we discussed last year. Is this what you are referring to or did I miss what you were saying?

 

 

Been proposed that the "S" signature is the RFD coming around the south side of the tornado. It matches up with the idea that the RFD can help give the storm it's final spin to drop the tornado. And what HM said - that was added as I'm typing.

 

 

Thanks guys.  Both times I've seen this it turned out to be a null case (although a rope funnel might not be considered null), and so I was curious if it may have a destructive influence on tornadogenesis.   Fully admit though that 2 cases is not significant.   I'll reread the Markowski paper.

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On the issue of yesterday's forecasts, the GFS did have some small errors that may have contributed to the less threatening forecasts in the morning. Comparing the 00z 5/15 run's 24 hr plots to the 00z 5/16 initialization, there was some erroneous moistening / cooling going on in SW Texas at 850-700mb.

Here is the MAF 00z 5/16 sounding and the 700mb / 850mb initializations of the GFS:

http://www.spc.noaa.gov/exper/soundings/13051600_OBS/MAF.gif

http://www.twisterdata.com/index.php?prog=forecast&model=GFS&grid=3&model_yyyy=2013&model_mm=05&model_dd=16&model_init_hh=00&fhour=00&parameter=DPTC&level=850&unit=MB&maximize=n&mode=singlemap&sounding=n&output=image&view=large&archive=false

http://www.twisterdata.com/index.php?prog=forecast&model=GFS&grid=3&model_yyyy=2013&model_mm=05&model_dd=16&model_init_hh=00&fhour=00&parameter=TMPC&level=700&unit=MB&maximize=n&mode=singlemap&sounding=n&output=image&view=large&archive=false

This is what the 00z 5/15 run looked like:

http://www.twisterdata.com/index.php?prog=forecast&model=GFS&grid=3&model_yyyy=2013&model_mm=05&model_dd=15&model_init_hh=00&fhour=24&parameter=DPTC&level=850&unit=MB&maximize=n&mode=singlemap&sounding=n&output=image&view=large&archive=false

http://www.twisterdata.com/index.php?prog=forecast&model=GFS&grid=3&model_yyyy=2013&model_mm=05&model_dd=15&model_init_hh=00&fhour=24&parameter=TMPC&level=700&unit=MB&maximize=n&mode=singlemap&sounding=n&output=image&view=large&archive=false

This small error actually had major implications for eastern Texas. The 850mb picture was way off, with deep moisture ending up further east than depicted. Also, this small error in moisture contributed to weaker modeled winds too, given the gradient ended up stronger than indicated.

That's all it takes folks!

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Basically, the 00z GFS put too much emphasis on this second wave in W TX while the first was still dominating (700mb closed low in OK, weaker moisture return in S TX to the second wave, better gradient and therefore better wind).

Edit: For reference, here is the 13z outlook yesterday which kind of reflects the 00z GFS issues to some extent with the segmented tornado probabilities and westward placement of severe risk:

Pay close attention to the tornado graphic:

http://www.spc.noaa.gov/products/outlook/archive/2013/day1otlk_20130515_1300.html

http://www.spc.noaa.gov/products/outlook/archive/2013/day1otlk_v_20130515_1300.gif

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