2019-05-17 EVENT: TX/OK/KS/CO/WY/NE/IA

Apr 5, 2015
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Norman, OK
Increasingly interested in a Nebraska target. Looking around at overall synoptic evolution and forecast soundings.. My original target of W KS is becoming less and less promising, with increasing 700 mb temps throughout the afternoon and evening. This is less of a problem farther S into TX PH.

Nebraska, roads and convective mode questions aside, looks ready to go, however. Modified 23z sounding (00z is contaminated by QPF) is... pretty good, to say the least.
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For comparison, a modified DDC sounding is good, but the capping raises concerns for a blue sky bust.

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This is alleviated a bit farther S into the panhandles.

I'm not sure where I want to go at this point. The north target, as usual, has more storm mode issues, but with Nebraska there's also the dreaded roads issue. Farther south, a cap bust is absolutely possible, but it's tough to say at this point which is better. I have time to decide but it's tough right now to decide either direction.
 

Jeff Duda

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Increasingly interested in a Nebraska target. Looking around at overall synoptic evolution and forecast soundings.. My original target of W KS is becoming less and less promising, with increasing 700 mb temps throughout the afternoon and evening. This is less of a problem farther S into TX PH.
I agree that NE is starting to look more promising over my initial W KS target (although there is still time to decide between the two). My primary concern with NE is that even RM storm motions still have a large northerly component, which means updrafts are going to tend to get pushed across the WF and into stable air (and the WF itself does not look to make much Nly progress during the day). The region of favorable low level shear is pretty narrow in NE, so a storm is going to have to more-or-less latch onto the WF in order to give anything more than a flash-in-the-pan show. Perhaps we will get lucky with moisture pooling closer to the triple point and sagging south along parts of the dryline.

Granted, if moisture verifies better than forecast, then it will also be possible to play both targets by starting north first then dropping south towards the evening.
 

Jeff Duda

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I say all that and then just saw the 18Z 3 km NAM. Boy that is an unnattractive looking reflectivity field (storm mode wise). It also seems like the WF is forecast to have a more WSW-ENE orientation than I had been seeing previously, however. In fact, the 18Z 3 km NAM spits out a couple of coherent UH tracks in NE CO including a whopper of a long-tracker that seems to ride pretty close to the WF from Brush up through Sidney, which could prove to be pretty easy to chase and entertaining to boot!
 
Mar 8, 2016
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Bloomington, IL
My concerns over the low warm front residency time and subpar road options are probably going to keep me in West Kansas chancing a cap bust over Nebraska at this point. Being an Illinois chaser, I love a good warm front chase but that warm front setup in Nebraska is generally not what I look for if I want a good warm front rider personally.
 
Jun 16, 2015
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Oklahoma City, OK
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I still see mixed signals for Friday, at least along the dryline target from, let's say, southwestern Kansas to the Texas panhandle/Northwest Texas.

Confidence remains relatively high across the Nebraska vicinity, but caveats include storm mode and tendency for storms to, potentially, cross over the warm front into a more stable near-surface layer. I'm relatively confident that something is going to go up in Southwest Texas as well, but chase terrain/road networks start getting kinda iffy down by I-20 and especially around I-10. Still, any semi-discrete storm that goes up in that environment will most likely become severe, rapidly.

The global, high resolution and convection allowing models are all over the place for dryline convective initiation (CI) in that middle area. The 3km NAM has, for three runs so far, shown virtually no CI in that area. On the other hand, the GFS and RGEM have signals of discrete/semi-discrete convection in or near the eastern Texas panhandle. The NSSL WRF seems to split the difference, although it initially convects up and down the dryline from the Texas South Plains right up into Kansas. Upon closer examination, it initiates from the panhandles into western Kansas, but struggles to sustain this convection. Meanwhile, to the south, it blows up an MCS-like feature down into Northwest Texas.
SREF_prob_combined_0.01_30_2000__f051.gif
The SREF mean highlights the two higher confidence targets well, if you look at probabilities for >2000 J/kg MUCAPE, 0-6km shear >30 knots and 3hr convective precipitation at 00z Saturday. Even though there's a relatively minimum in the middle, you could argue that you'd rather have sparse/little convection along the dryline. Given large scale forcing, which is more than adequate, should any surface-based convection initiate along the dryline around the 22-00z time frame, it's hard to see why it wouldn't become severe.
 
Jun 4, 2018
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San Angelo, TX
I will be targeting SW Texas. The capping issues are what concern me the most, but the last couple of runs of the NAM seem to be showing the cap eroding over a wider area in the early to mid afternoon and mostly staying that way, especially SW of SJT. We are getting into the outer limits of the RAP's range now too. I won't pretend to know enough to be able to tell you whether it's accurate that far out or not, but the 09z run does seem to be trending similarly to what the 06z NAM was showing. As stated before, the road network isn't great, but the northern targets aren't an option for me logistically, so I'm hoping for the best. Luckily it is looking decent so far.
 
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Sep 25, 2006
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Minneapolis, MN
I think the warm front is going to be the best target tomorrow. HRRR really cranks out a few storms in southwest Nebraska and with amply instability and shear, I think it has the best chance to produce. Only thing that would worry me is if storm motions don't cooperate with the orientation of the warm front. However, it looks like storms will be moving NE to NNE and the warm front looks like it will be orientated SW-NE in that area. HRRR still doesn't show much for initiation along the dryline to the south.
 
May 18, 2013
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The HRRR is finally in range, and it isn't looking good for southern plains chasers for Friday. Today's 12z HRRR shows zero convection at 0z 5/18 in any of the states listed in this tread title. It does fire in Nebraska. Another interesting thing is it shows the dryline all the way to the TX panhandle / western OK border by then. If there is a silver lining it is it looks like the cap is just about gone by then in a narrow corridor to the east of the dryline. It's still early - but this is by no means a sure thing in TX.
 
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I agree with everything @Dean Baron and @Randy Jennings are saying, and noticed the same thing. RAP and NAM both have some activity on the Eastern TX Panhandle, which is looking like the best option for people not able to make it to NE.

Southwest TX is looking more and more like it's out of the game, unless you plan on doing night time chasing. Both the RAP and NAM show things firing up around midnight Friday night for Southwest TX.

Kansas though... I completely overlooked KS. 3,000 J/kg CAPE, 45kt Shear, strong dryline, and Significant Tornado Convectives on both the RAP and NAM. For everybody who though KS was out of play... it might be worth taking another look.

I think there will be tornadoes tomorrow. As far as where though... I think it comes down to timing with NE and KS looking good during the afternoon and evening, and TX looking good in the evening into the night.

All of that said... I'm 90% sure on heading to Southwest NE (probably North Platte) and making another decision once I get there. I'll look a the HRRR again this evening just to confirm before I head out tomorrow morning.
 
Jun 1, 2008
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Friday Nebraska is more certain; however, I think northwest of Edwards Plateu of Texas makes a good chase target.

Instability is no issue. It's a little warm at the mid-levels, but above that EML lapse rates are excellent.Turning with height is plenty enough. LLJ is actually pretty backed. Upper jet is slightly more veered than points north, but not as strong.

As for CAMs, the ARW/NSSL version of the WRF does convect by 00Z. Experimental HRRR does too.

Finally, the southern target probably sets up for Saturday, not that it's a great chase day.
 
Jun 16, 2015
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I'd have to argue differently about Southwest Texas on Friday. Most models convect prior to 00z in that area. The only notable exception is the 12z HRRR, but it's the first run into range and at the 36hr panel, there are hints at convective initiation and a few pixels start showing up in the simulated reflectivity fields. Also note that climo favors convection down there, as we've seen on at least a few occasions thus far this spring.

The HREF members largely initiate around 21-22z in Southwest Texas. Here are the UH tracks to give an idea of storm placement and path/length. Notice that by 23z, multiple members show ongoing, robust convection, while the signal to the north is very sparse/questionable. (I removed -12 hour model runs, to keep the data most up-to-date, although the signal has been consistent for multiple model cycles)
uh25_004hmax_pb075.sp.f03500.png
The 12z GFS begins to convect around 21-00z in far southwestern Texas, although the QPF signal is notably stronger after 00z. I'd argue for discrete convection, you'd want a more limited signal, as opposed to storms blobbing up into a cluster or MCS.
 
Sep 25, 2006
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Minneapolis, MN
FWIW the 12z HRRR also blows up a storm in NW Iowa around 22-23z right on the warm front. The warm front itself is oriented more west-east in this area but storm motions look to be more west-east as well so if a storm does go up in NW Iowa, it could have a chance to latch on to the warm front and be a sleeper target tomorrow. Ample instability will be in place and with sruface winds out of the southeast @ 15-20 knots, it should be a good environment if initiation actually occurs.
 

Jeff Duda

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Things can certainly still change with updated model runs throughout the day, but after checking 12Z stuff I am basically calling off W KS as a target and instead am going more for the triple point/WF across far NE CO and into the NE PH. Pretty much all of the CAMs initiate rotating storms in the area, and there seems to be a more favorable SW-NE orientation to the warm front (WF) in that region compared to further east. Moreover, there are indications that the region immediately north of the western part of the WF will remain relatively clear, thus allowing for substantial destabilization. Combine that with a ribbon of moderate moisture content (mid-upper 50s dewpoints across that terrain is very good for May) and easterly winds and it makes sense that storms go up there and survive for a few hours before plunging too far into the cooler air well north of the front. The CAMs are also much less friendly towards developing sustained convection along the dryline, so I'm thinking the cap may largely win out down there.
 

Dan Robinson

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Last few runs of the CAMs have the cold front blasting southeast all the way into central Kansas by 07z. It looks like much of the NE storms that fire either do so just ahead of the front, or behind it. That cold front is going to be the factor of whether not only this day, but the next three days all bust hard.
 
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Jul 5, 2009
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Just took a cursory glance at the OZ runs of the NAM and HRRR valid at 0Z Sat May 18. If I were chasing I would favor the northern target area. I am generally always biased toward a triple point play. HRRR has some really nice UH signals in Nebraska. There is one lone track in southwest TX but quite frankly I can’t understand why. I assume the terrain is assisting with convective initiation because there really is not much convergence along the dryline, with winds more southerly on both models. The cap is also stronger as you go south in TX. Convective initiation will not be a problem near the triple point and under the exit region of the jet. Another thing I don’t like about SW Texas is the lack of a strong LLJ. There are only three potential negatives I see in Nebraska: the 500mb winds are a little more meridional than I would like, which not only affects shear but could also push storms more quickly north of the front; storm mode could be an issue if cells are numerous and interfere with each other; and, having not refined a particular target, the sparse road network if the Panhandle ends up being the target area (or cells moving from NE Colorado into the NEB panhandle. If someone were logistically limited to TX it’s certainly worth taking a shot along the dryline, if something goes it could be a beautiful isolated supercell but with a limited LLJ and high temp-dew point spreads I wouldn’t expect a tornado.
 
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Looking at the latest runs of the CAMs, they all initiate something in far NW Kansas or near the KS/NE state line, then move it northeast into NE. Specific locations and details vary, but they all seem to be picking up on that general idea. By around sunset it looks like the storms could cross north of the front (and thereby become elevated), but there seems to be pretty good agreement on the general idea of storms initiating in northwest KS or near the state line moving up into NE during the time period between about 21Z and 3Z. Given the environment, the storms are very likely to be supercells with potential for tornadoes and very large hail. I have prepositioned in Lamar, CO for tomorrow's chase, and unless things look a lot different in the morning, will probably head to northwest KS and expect to track the storms into NE.
 
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Jul 5, 2009
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Newtown, Pennsylvania
The synoptic front has more of a cold frontal push look to it in NEB northeast of the triple point. Looks like you would have to go to northeast NEB / southeastern SD for a warm front segment with backed winds. However, the HRRR shows no convection in that region as it is likely too far removed from the stronger forcing, especially given the axis of the stronger cap - 11-12 degrees C - is nosing up that way at 0Z. Road flooding is an issue up that way anyway.

There are some hellacious UH's along the front near and east of the triple point per 10Z HRRR. Agree with @John Farley that if looking for a more isolated / discrete supercell that is not in danger of crossing north of the front it might be best to head south toward the NEB/KS border, just east or southeast of the surface low. If I were out there today, I would probably initially stage in North Platte and from there decide whether to adjust within that general area to play the triple point or drop south toward McCook for the more southern play.

HRRR continues to show a lone cell down in southwest TX yet the parameter space per NAM and RAP just does not look anywhere near as appealing down there. I assume that CI is terrain-induced but with a weaker LLJ that doesn't strengthen until after 0Z and high temp-dewpoint spreads I wouldn't expect a tornado down there, but what do I know...

EDIT: originally had a typo mentioning southeast TX but meant southwest TX. And sure enough I know nothing because as I edit this at 6:10pm CDT there was already an isolated supercell down there with a confirmed tornado.
 
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Todd Lemery

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Jun 2, 2014
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Just a quick note. Like most people, I’ll be heading toward the Western Kansas/Nebraska border today. If I had any confidence something would pop further down the dryline in KS I would wait there instead. That could still change for me. Good luck to everyone out today and drive safe!
 
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Sep 29, 2011
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Woke up to see my target was more or less centered in the region killed off by the 6Z SPC outlook...I could only smile. h5 VVs have been dead the entire length of the build up to this system within the past several days, and when you add in a rare HRRR storm boycott, it doesn't bode well for those of us who chose the southern target (in any part of it). As previously mentioned, even if that TEC happens in deep SW Texas, the shear environment (IMO) just doesn't look conducive to tornadoes....but then again there's ALWAYS a tornado-warned sup in that area while other storms struggle north of it.It Looks like it would be a long, all-day wait, then turkey towers, then maybe some echoes, followed by a struggling updraft that dies with the setting sun. I've seen that way more times than I've seen a tornado in this situation. Still time to re-consider but the window is closing. Current data isn't changing my mind,
 
Jun 4, 2018
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San Angelo, TX
Woke up to see my target was more or less centered in the region killed off by the 6Z SPC outlook...I could only smile. h5 VVs have been dead the entire length of the build up to this system within the past several days, and when you add in a rare HRRR storm boycott, it doesn't bode well for those of us who chose the southern target (in any part of it). As previously mentioned, even if that TEC happens in deep SW Texas, the shear environment (IMO) just doesn't look conducive to tornadoes....but then again there's ALWAYS a tornado-warned sup in that area while other storms struggle north of it.It Looks like it would be a long, all-day wait, then turkey towers, then maybe some echoes, followed by a struggling updraft that dies with the setting sun. I've seen that way more times than I've seen a tornado in this situation. Still time to re-consider but the window is closing. Current data isn't changing my mind,
This is exactly where I'm at too. With each model run, I get more doubtful. With the exception of the SPC mesoanalysis showing the cap eroding within the next few hours, the only saving grace is that because I live in San Angelo, maybe I'll get lucky and something will pop within driving distance without having to commit an entire day to sitting in rural west TX with my fingers crossed. Good luck and safe travels to everyone out there today. That northern target is looking pretty good
 

Dan Robinson

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Northern target: Surface winds cranking nicely but failing to back. Worried about resulting weaker convergence on the dryline, although winds behind the DL are pushing decently. Some pesky high cirrostratus/cirrus threatening to interfere with peak heating. RAP has a nice DL bulge NE of Colby, we'll see if we can get and sustain a storm there like the CAMs suggest.

On another note, I've been touring some of the county roads around Colby/Oakley/Grainfield, and everything is dry and in good shape. A few are being graded this afternoon. Of course that will change with storms later, but at least starting out, the road grid looks good to go.
 
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Jul 5, 2009
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In the NEB target area, convection has initiated well southeast of the triple point in the open warm sector. These storms are likely in a decent parameter space yet have no chance of latching onto the frontal boundary. Curious as to why these storms initiated where they did. Will this be the start of the main show or will there be new development back west closer to the surface low and dryline??
 
Sep 25, 2006
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Minneapolis, MN
I’m curious why the storm in extreme northeast CO hasn’t gotten a tornado warning. Looking at radar it appears it may be an L.P. supercell so it’s radar signature hasn’t been all that impressive. However, it has had a solid couplet on it for a while now and it continues to get stronger.
 

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Jesse Risley

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Apr 12, 2006
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In the NEB target area, convection has initiated well southeast of the triple point in the open warm sector. These storms are likely in a decent parameter space yet have no chance of latching onto the frontal boundary. Curious as to why these storms initiated where they did. Will this be the start of the main show or will there be new development back west closer to the surface low and dryline??
Just taking a glance at the upper air data on mesoanalysis, those cells seem to be co-located with the right quadrant of main 500 mb energy and associated cooling temps AOB -11C. CINH has mostly eroded beneath the cooling aloft in the last 2 hours or so. Surface observations show appreciable pressure falls along and west of the line of convection, from Holdredge, NE to Russell, KS and westward.
 
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