2015-04-16 EVENT: TX/OK/KS/NE

[Royce Sheibal]

No one seems to be talking about Thursday yet, so here we go!

SPC is not impressed with Thursday, clearly, as they poke a little marginal into TX and OK and that's it. NAM is covered with leftover convection from Wednesday night, and even the GFS is covering the area in leftovers. But take a look at the 12z NAM 4km. I've been a big fan of it as of late. The Updraft helicity forecast has been very interesting and pretty insight lately. Although the forecast is on the edge of the run, the 50-100 UDH line along the panhandles is worth noting. Also notice the big blobs down in central TX and even the KS/NE border. Suddenly this might be a good day after all.

If you want to talk the straight NAM or GFS, both runs look like they are factoring in too much ongoing precip. With temps forecast to be in the 70's and dewpoints at or above 60 from W TX all the way to Omaha, how can Thursday not produce something? 850's will be roaring out of the south and there is even upper level support with incoming DPVA. Too Many solid ingredients not to produce something.

I'd be willing to bet there will be a couple good chase-able cells in our more classic chase areas. TOR chances may be low, but depending on morning convection burning off, Thursday may have some action.

 

[Jeff Duda]

I can see why the folks at SPC wouldn't be particularly impressed with this event as of right now. Everything looks pretty marginal. There's also a spatial disconnect between the best mid-level flow and the thermodynamics. In fact the mid-level flow looks pretty crappy above the warm sector. Moisture isn't the greatest either, except perhaps in the TX PH, where mid-upper 50s can get the job done given there's great low-level shear and the mid-levels aren't too dry. Low-level shear doesn't exactly scream tornado event, but it doesn't look like mid-level moisture will be a problem.

The 4 km NAM nest really likes that cold front across KS/OK PH/TX PH. None of the other models are really in agreement with that right now. The SREF in particular is not too keen on much happening. Very low probabilities of even 1000 J/kg MLCAPE making it as far north as Lubbock. Shear looks alright, but not great either.

Seems like there is potential for something worthy of a slight risk designation from SPC, but given the amount of disagreement between the deterministic runs and the low probs from the SREF, they probably just don't have enough confidence to go with a higher risk category right now. Certainly bears watching, however. Change a detail or two in the favorable direction and this could become a solid setup.

 

[Brandon Lawson]

Thursday continues to hold promise, despite the model discrepancies. It's all going to come down to the placement and evolution of the closed low. Tonight's 00z NAM shows a more positive tilt trough, with forcing ill-timed, but much better moisture and instability across the Texas Panhandle than what we saw last Saturday. Meanwhile, the GFS has the low more neutral tilt and better timed, with a developing surface low and a more stout dryline across western OK/northwest TX. Either way, the cap doesn't appear to be an issue and there should be at least some instability and adequate shear for organized storm development. It's almost always worth it to venture into the Panhandle when you see 2000+ CAPE. Boo... I didn't beat the SPC Day 2 Outlook.

 

[Royce Sheibal]

Well, I'm quite happy with how my original forecast is panning out. Thursday is going to be a strange day (as will most likely Friday, Saturday, and Sunday). We don't get a lot of cut-off lows sitting over New Mexico this time of year. NAM and GFS are falling in line with NAM 4km. Cape is looking good, moisture is ok, shear is ok. DPVA is gonna be rocking. Storm motions are going to be freaky. Anything that forms in W OK or SW KS is going to have NNE or even due North storm motions... Anything super-cell that can split right away from the main flow will be able to catch some inflow, in particular in KS where surface winds may still be from the E/NE. As for you guys down in W TX, your storm motions will be more traditional, just hope that your T/Td spreads aren't too high and you might get some TORs.

My target if I wasn't working: Witchita, KS. The LI's approach -10 on the NAM just to your south, and the best EHI should be somewhere to your NW, sadly shear is poop here unless you get a lucky right turn. If worse comes to worse you can bolt west and head to Dodge City. Amarillo might be another winning spot closer to the DPVA, and with better shear, but I'm just not totally impressed with the soundings in that area.

 

[James Langford]

We've been watching this day for a few days now, generally going off the NAM. I'm encouraged by what I am seeing in the latest 12z NAM run. Previously we had a lot of early morning messy convection and clouds that could have caused some issues. That no longer seems to be as much of an issue. Really like the 500 / surface crossover with great backed surface winds. Placement of upper level low and surface low look excellent for a target of 287 from Amarillo down to Childress.

 

[Gabe Garfield]

Well, I'll be darned! This setup actually looks pretty nice!

In the usual fashion of cut-off lows, the hodos are shifted a bit to the left, courtesy of that nice meridional flow. Usually, though, we don't see much instability with these type of systems, because mostly-southerly flow doesn't result in a lot of downsloping and associated EML development. But I guess the EML from last week was a hoss, because the models are still forecasting strong instability (2000 - 3000 j/kg) to develop in the models over the E TX Panhandle tomorrow. Additionally, forecast mid-level flow should support supercell shear (alliteration unintended), with 850/500 crossovers strongly supporting isolated supercells.

The only weakness I see is low-level shear, which is rather paltry at 00z (~100 m2/s2). This should, as always, increase toward 03z. But unlike recent setups (that cap the heck out of anything after sunset), days of rainfall have worked on the cap a bit, so we might see a tornado threat develop after dark. Should be interesting!

 

[Ben Holcomb]

Just going off the NAM here, but it seems like there should be concern for early development, in the 2-3pm range. The cap looks to be completely gone at 21Z and it looks like CAPE values fall drastically from 18 to 21Z then 21Z to 00Z which makes me think there will be precip ongoing.

This has me worried that things can go bad, but if we can hold off until after 5pm for storm development I think it will be a great day for the few who make the trek out there. That cutoff low really seems to make it over the panhandle with 50-60kt 500mb flow at 00Z.

As Gabe said, by 03Z the hodos really curve as the LLJ kicks in. Good S to SE 850's all day. I'm excited and have already gotten out of any commitments I have tomorrow. It looks like a drive to the panhandle is in order, but I don't want to leave Norman any later than noon.

 

[James Gustina]

Whether or not it's an early show is really gonna come down to the mesoscale factors in play since the overall synoptic setup isn't particularly traditional in terms of what you usually see this time of year. Being out there and ready to go just off the Llano Estacado by 3 looks to be a good bet due to the relatively weak cap. I'm really encouraged by those 30 kt SE H85 winds with winds backing at the sfc by 21Z. A nocturnal tornado threat in the E PH materializing with enlarging hodographs would not surprise me.

I'm gonna have to double time it tomorrow since I won't be able to get out of Norman until 1 sadly. Also a word of caution, playing between Turkey and and Clarendon is gonna be tough going, all the recent rainfall out there has probably ruined a lot of the somewhat passable roads closer to the Prairie Dog Town Fork of the Red River.

Initial Target: Clarendon, TX

 

[Wesley Luginbyhl]

Still plenty of things that can go wrong with this setup, but the positives are hard to ignore especially being a local setup to me. Generally this is based on the NAM, but takes into account most other models that I have glanced at here at 2am.

The negatives. First, how much early precip will there be and where. We all saw what happened to the Camargo,OK storm last week when it ingested air from early day storms. Will enough moisture make it? Probably, but the only model that does not mix out the 60 dew points is the GFS. Moisture depth I believe will be ok, based on the Norman sounding (Fort Worth was missing) and depth down on the coast (up to the 750mb to 725mb at Corpus). If the mixing is less than most the models show that would be a major plus, but also aids in earlier initiation with the limited capping. The 500 flow is almost parallel to the dryline, mostly north of Dumas. In turn, the 500mb flow is weaker SE of there (40kt down to 25 kt), as are the 850s at 0z. 3-28-07 had a similar alignment (of flow and of the dryline) and it worked out fine then, but I am still cautious about storm clustering and interference north of Dumas.

These concerns leave me split on a target for now. One side of me leans to Guymon, OK for the better 500 and 850 winds. 850s are 10-20kts better up there, especially after 0z. Looks like 55 dews in this area, which should be enough but doesn't leave much wiggle room. The other target would be from Pampa, TX to Clarendon, TX. Dews should be closer to or above 60 in this area. Storms that do form should get off the dryline better. Northern target would likely fire sooner than the southern one, but just how early is the question. I dont leave work till noon out of Amarillo, so hopefully my target will be clear by midday tomorrow as I see both with a chance to produce something. 850's with a SE'erly component in the Panhandle are always a good thing. (Side note - It just seems like one of those days that starts off with a tornado report in eastern CO)

 

[John Olexa]

Watching on TV. Storm near Pampa is trying hard.

 

[Kevin Rimcoski]

It's my birthday and I knew I should have taken today and tomorrow off for today's chase

 

[Steve Miller TX]

Very interesting radar image. https://www.facebook.com/NWSAmarill...8741279137778/996737983671433/?type=1&theater

 

[Kevin Rimcoski]

Wow that's imteresting...usually the anti cyclonic rotations are to the southwest of the cyclonic right?