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Active Severe Weather Pattern Beginning Next Week


Jim Martin

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00z NAM paints a dangerous picture across the current ENH risk area--and especially in KS-- tomorrow by as early as 18Z. Widespread 0-1KM SRH of 200-300m2/s2 by 00z, and even better 0-3KM SRH. Here is a sounding from 00Z tomorrow in S KS. 00_NAM_024_37.44,-98.77_severe_ml.png

yup - I expect that moderate to extend southward for intensity but would not be surprised at only an enhanced given spatial coverage expected on lower end. Love dry lines for that very reason
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I've been planning on chasing tomorrow for a few days now, but considering my starting point, range, and need to return for commitments the next day, I'm going to have to play way far south down the dryline, likely remaining in Texas or perhaps crossing into far south Oklahoma. With that being said, much of the guidance is really frustrating with at least 50% of what I've been looking at completely decimating my possible target areas with overnight and morning convection. If things don't look better by tomorrow morning, I might just scrap my plans completely.

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KS might be about to put on a grand finale tomorrow. Aside from VBV up high (which is certainly not as problematic as down low below 500 mb), the mid/low levels on both the NAM and GFS generally have classic tornadic supercellular hodograph structure and obviously high CAPE again. Storm motions will be faster tomorrow with the stronger wind fields in place.

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Well Ian needed some of my mojo yesterday so I guess we're even lol.

Pretty sure I saw like a thousand tornadoes yesterday. ;) It happens... You will miss cool stuff while chasing, guaranteed.
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I meant after Sun/Mon heh.

I think this one blows those cleanly out of the water obviously.

Yeah true. Sunday was bad luck as much as anything. Monday was poor decision making. But both happen plenty. I know it sucks though I always let it get to me even though I shouldn't.
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KS might be about to put on a grand finale tomorrow. Aside from VBV up high (which is certainly not as problematic as down low below 500 mb), the mid/low levels on both the NAM and GFS generally have classic tornadic supercellular hodograph structure and obviously high CAPE again. Storm motions will be faster tomorrow with the stronger wind fields in place.

 

 

 

How is Friday looking for you?

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Yeah tomorrow is starting to have that feel.

most guidance has been pretty incessant about KS being big tomorrow... And it looks better now than it did even a few days ago. Not perfect by any means, but still more than good enough (considering the impressive low-levels) for multiple tornadoes, some likely being strong and long-tracked. A little concerned by the storm motions shown by the NAM, but that will only matter if there are tons of storms, and if storms decide not to be right movers. Given th amount of low-level turning, I'd expect quite a few deviant right movers.
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Tomorrow may get very active early.The veer-back or veer-back-veer wind profiles may be something holding this back from having several classic supercells in the warm sector. Despite this issue, I'd say that there will probably be several tornadoes, in perhaps messy storm modes or clusters. The dew points will be above 70 in several spots. Northern Kansas will see 0-6km shear up around 50 kt. Storm relative helicity could be pretty high wherever the outflow boundary is/ and wherever the winds are more easterly. The storms definitely won't be isolated by hundreds of miles, like today. There's a chance that some storms pop up in Oklahoma, but they will still suffer (a little) from veer-back-veer and from lack of higher SRH.

 

The WRF-NSSL lays out a pretty big stable-air outflow boundary in northeast Kansas early, then has discrete cells, then a cluster by 21z.

 

edit: if you checked some of the sharppy-based forecast soundings for Kansas, from the earlier (12z or 18z) runs of the 4km NAM, there were some spots of 8000 J/kg.

 

edit: looks like Vance radar is broken right now, and will be for an unknown amount of time.

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GFS is also electric for tomorrow across a similar area...

 

NOTE: Something to keep in mind about a few of the Hi-Res CAMS showing quick upscale growth tomorrow... They did that every day this week and failed for the most part (until later in the evening, after the tornado threat had begun subsiding anyways.) CAMs have not done too great recently with handling convection... Especially when it comes to them wanting to accelerate cold pool development-- its not going to happen until later. Another thing to note is that far S KS/N OK and W OK would still definitely be in play as well. Models are showing some weird convective-contamination of DPs and instability across SW/W OK from some convection in TX though, and i'm not quite sure what to make of it since most of them don't advertise convection significant enough, and close enough to mess up moisture that much... 

 

Nonetheless, if things remain discrete across KS, it will be a long day, and likely a tornado outbreak-- as long as LLVL/MLVL wind fields are of the magnitude/orientation as currently advertised... Things will almost certainly be discrete in OK, but coverage concerns as well as the aforementioned potential contamination throw a wrench in there, in addition to the possibility of slightly less impressive SRH... BUT latest NAM did show pretty impressive SRH along most of the dryline.

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Large non-hatched 10% TOR across only N KS and S NEB... with only 5% tor probs extending to the KS/OK border... Only 2% below that. Sounds like they are only interested in waiting for details to become clearer. Large 30% hatched hail area across KS/NEB, and another one in W/C TX.

DAY 1 CONVECTIVE OUTLOOK   

NWS STORM PREDICTION CENTER NORMAN OK  
0102 AM CDT THU MAY 26 2016  
 
VALID 261200Z - 271200Z  

   
..THERE IS AN ENH RISK OF SVR TSTMS ACROSS THE NEB/KS VICINITY
 
 
...THERE IS AN ENH RISK OF SVR TSTMS ACROSS PORTIONS OF WRN AND  
CENTRAL TX...  
 
...THERE IS A SLGT RISK OF SVR TSTMS COVERING A LARGE PORTION OF THE  
CENTRAL AND SRN PLAINS...AND PARTS OF THE MID AND LOWER MO VALLEY...  
 
...THERE IS A MRGL RISK OF SVR TSTMS EXTENDING FROM THE UPPER MS  
VALLEY/UPPER GREAT LAKES REGION SSWWD TO THE RIO GRANDE...  
   
..SUMMARY
 
 
SEVERE THUNDERSTORMS CAPABLE OF TORNADOES AND VERY LARGE HAIL ARE  
EXPECTED THURSDAY ACROSS MUCH OF THE SOUTHERN NEBRASKA AND KANSAS  
VICINITY...AND POSSIBLY INTO NORTHEAST COLORADO...AND EXTENDING  
SOUTHWARD INTO THE SOUTHERN PLAINS. OTHER MARGINALLY SEVERE STORMS  
WITH HAIL AND STRONG WIND GUSTS MAY OCCUR ACROSS PARTS OF THE MID  
AND UPPER MISSISSIPPI VALLEY AND WESTERN UPPER GREAT LAKES REGION.  
   
..SYNOPSIS
 
 
STEADY EWD PROGRESSION OF WRN U.S. TROUGH IS FORECAST FOR  
THURSDAY...WITH THE SYSTEM CROSSING THE ROCKIES THROUGH THE DAY AND  
NOSING INTO WRN PORTIONS OF THE PLAINS STATES WITH TIME. AS HEIGHT  
FALLS OVERSPREAD THE CENTRAL PORTION OF THE COUNTRY...A LEE LOW OVER  
THE CENTRAL HIGH PLAINS IS FORECAST TO DEEPEN INTO WRN KS DURING THE  
AFTERNOON...WITH A WARM FRONT EXTENDING NEWD INTO SRN NEB. THIS LOW  
AND WARM FRONT...A DRYLINE EXTENDING SWD ACROSS OK/TX...AND RESIDUAL  
OUTFLOW BOUNDARIES IN THE WARM SECTOR WILL LIKELY FOCUS SEVERAL  
AREAS OF SEVERE STORMS THROUGH THE PERIOD.  
   
..CENTRAL AND SRN PLAINS VICINITY
 
 
A VERY COMPLEX/UNCERTAIN SCENARIO IS UNFOLDING ONCE AGAIN FOR  
THURSDAY WITH RESPECT TO TIMING/LOCATION AND SPECIFICS OF EVOLUTION  
OF WHAT WILL LIKELY BECOME WIDESPREAD CONVECTION ACROSS PARTS OF THE  
CENTRAL AND SRN PLAINS REGION. ONGOING STORMS ATTM -- AND  
ADDITIONAL EXPANSION OF CONVECTION THROUGH THURSDAY MORNING -- WILL  
BE THE PRIMARY COMPLICATING FACTOR...WITH SWATHS OF THE WARM SECTOR  
BECOMING CONVECTIVELY OVERTURNED AND ASSOCIATED OUTFLOW BOUNDARIES  
BECOMING ESTABLISHED IN HERETOFORE UNCERTAIN LOCATIONS.  
 
WITH THAT SAID...THE BROADER PICTURE -- WHICH INCLUDES A LARGE WRN  
UPPER TROUGH AND ASSOCIATED/ENHANCED SWLY FLOW ALOFT SPREADING EWD  
TOWARD THE PLAINS ALONG WITH A VERY MOIST WARM SECTOR BENEATH VERY  
STEEP LAPSE RATES THROUGH MUCH OF THE TROPOSPHERE -- IS SUGGESTIVE  
OF AT LEAST LOCALLY SUBSTANTIAL SEVERE POTENTIAL. ALONG WITH RISK  
FOR VERY LARGE HAIL...LOCALLY DAMAGING WINDS AND TORNADOES WILL ALSO  
BE POSSIBLE. ATTM...TWO MAIN CORRIDORS OF SEVERE RISK INCLUDE:  
 
1. SRN NEB AND MUCH OF KS -- AND POSSIBLY INTO NERN CO -- INVOF THE  
FORECAST-TO-BE-DEEPENING SURFACE LOW AND ASSOCIATED WARM FRONT...AND  
POTENTIALLY AN OUTFLOW BOUNDARY LINGERING OVER CENTRAL AND ERN KS  
 
2. PARTS OF W CENTRAL TX INCLUDING THE CONCHO VALLEY AND BIG  
COUNTRY REGIONS AHEAD OF THE DRYLINE  
 
AS MENTIONED ABOVE...VERY STEEP LAPSE RATES ALOFT /AWAY FROM AREAS  
WHICH EXPERIENCE PRIOR CONVECTIVE OVERTURNING/ ATOP A VERY MOIST  
BOUNDARY LAYER WILL PROVIDE A VERY FAVORABLE THERMODYNAMIC  
ENVIRONMENT TO SUPPORT VIGOROUS STORMS...AND 45-55 KT SWLY MID-LEVEL  
FLOW SPREADING EWD ON THE ERN PERIPHERY OF THE UPPER SYSTEM WILL  
CONTRIBUTE TO SHEAR SUPPORTIVE OF SUPERCELLS. AGAIN  
THOUGH...NARROWING DOWN TIMING AND SPECIFIC LOCALES OF GREATEST RISK  
REMAIN DIFFICULT ATTM...WITH AN ARRAY OF THE LATEST PARAMETERIZED  
AND CONVECTION-ALLOWING MODELS EXHIBIT DIVERSE/DISPARATE SOLUTIONS  
REGARDING CONVECTIVE TIMING/INITIATION/PROGRESSION. THOUGH THE  
ENVIRONMENT APPEARS SUPPORTIVE OF RISK FOR VERY LARGE  
HAIL...DAMAGING WINDS...AND A FEW TORNADOES...DETAILS PRECLUDE ANY  
FURTHER SPECIFICATION ATTM.  
   
..UPPER MS VALLEY/UPPER GREAT LAKES VICINITY
 
 
ISOLATED STRONG/LOCALLY SEVERE STORMS WILL BE POSSIBLE ACROSS  
PORTIONS OF THE UPPER MS VALLEY/WRN UPPER GREAT LAKES REGION  
THURSDAY AS SHORT-WAVE TROUGHING SHIFTS ACROSS THE AREA DURING THE  
AFTERNOON. WHILE AT LEAST PARTS OF THIS REGION -- LIKE AREAS  
FARTHER S -- WILL LIKELY EXPERIENCE EARLY PERIOD CONVECTION...SOME  
DESTABILIZATION COMBINED WITH MODERATE /40 TO 45 KT/ MID-LEVEL WLYS  
WILL SUPPORT RISK HAIL/DAMAGING WINDS WITH A FEW OF THE STRONGEST  
STORMS.  
 
..GOSS/MOSIER.. 05/26/2016  

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Not a hatched 10% lol

An odd outlook to me, especially with where the 10% area is exact (including a large part of Nebraska)... Guess they're just waiting for more details to come into focus... 

 

Not like it matters I guess. Today we got a long-track violent tornado in the 2% risk. lol SPC has been weird this year... Especially since 4/26.

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NOTE: Something to keep in mind about a few of the Hi-Res CAMS showing quick upscale growth tomorrow... They did that every day this week and failed for the most part (until later in the evening, after the tornado threat had begun subsiding anyways.) CAMs have not done too great recently with handling convection... Especially when it comes to them wanting to accelerate cold pool development-- its not going to happen until later.

Maybe when the convection-allowing models see 6000 J/kg of CAPE they all say, "Convection!!!!!! Yay!!!!!!!!!!!!" and forecast thunderstorms everywhere.

 

Edit: there is a tornado warning at this moment in Iraan TX. People may be going to their shelters at 1:29AM CDT or 12:29 AM MDT (can't remember if that section is on Mountain time.) Pretty good rotation and 1" to 3" hail.

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Why is so much of Nebraska under 10% tornado probabilities? That has almost no support from models/trends/etc.

similar question to how many licks does it take to get to the center of a tootsie pop... The world may never know.

On a serious note, that is a great question. Right when I saw that in the outlook I said to myself "what?" Also with only a 2% TOR in every portion of OK...

Anyways, as has been the case recently... The HRRR has no earthly sense of what it is doing, or what is going on.

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An odd outlook to me, especially with where the 10% area is exact (including a large part of Nebraska)... Guess they're just waiting for more details to come into focus... 

 

Not like it matters I guess. Today we got a long-track violent tornado in the 2% risk. lol SPC has been weird this year... Especially since 4/26.

 

 

Between SPC and NHC there to me, anecdotally, is a distinct counter (sometimes over) reaction to a "blown high" forecast (in the latter case, a TC they forecast to, say, Cat 3 that is blown apart by shear after reaching low Cat 1) - for the next 3-4 TCs they'll under-forecast intensity, or in the case of SPC, for the next 3-4 possible outbreaks they will paint risk areas below what they usually are based on the same model output.   Probably could be investigated formally through statistics. 

 

On the flip side there tend to be years where possible severe outbreaks or TC intensity consistently under or over performs modeling in mysterious ways, and their argument might be they are trying to capture that.  

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Well for those of you chasing today... You'll love the obs plot/vis-sat image as of 1230Z for the most part.

 

One thing I noticed in that visible imagery was some agitated CU in the OK & TX Phdls. I wonder if that is a really subtle piece of vorticity making it out already. 

 

BTW, is anyone else buying the early runs of the HRRR model?  Below is the image from the 11z HRRR valid at 18z, it is showing convection breaking out between 18 & 19z across W OK & S KS. The trends so far this week has been for the HRRR to break out convection earlier than it actually happened. 

 

hrrr_ref_kansas_129.png

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Will be heading west from KC after work today. Just don't know where. Hopefully the next model runs help shore up my decision. And hopefully I'm not too late.

 

Should I mention that I may be kicking myself a bit for not getting out yesterday? Yay, I'm kicking myself.

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I'd do SC KS... Despite the SPC TOR probs being meh down there, it holds the highest potential in my mind... Relatively isolated convection (possibly), a strong 50-60kt SLY LLJ by 00Z--likely with backed SFC winds, steep mid-level LSRs and impressive BL moisture creating ample instability, also don't think VBV will be too great in this area. ICT could be under the gun later, potentially. 12Z NAM does a good job of showing this. RAOBs from AMA/DDC/OUN indicated an impressive EML--especially at DDC. This however will not be the case later in the day as the S/W works it's magic. DDC also already had 50kt near westerly flow at H5, and ~90kt flow at H25.

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I'd do SC KS... Despite the SPC TOR probs being meh down there, it holds the highest potential in my mind... Relatively isolated convection (possibly), a strong 50-60kt SLY LLJ by 00Z--likely with backed SFC winds, steep mid-level LSRs and impressive BL moisture creating ample instability, also don't think VBV will be too great in this area. ICT could be under the gun later, potentially. 12Z NAM does a good job of showing this. RAOBs from AMA/DDC/OUN indicated an impressive EML--especially at DDC. This however will not be the case later in the day as the S/W works it's magic. DDC also already had 50kt near westerly flow at H5, and ~90kt flow at H25.

 

More of a trek than the north play though. Agh. Decisions. 

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