2011-05-24 FCST: KS/OK/TX

[Jordan Hartley]

This day looks down right scary for NC OK/SC KS. Pick your poison on which model you want to believe over the other. Both the NAM and GFS are hinting at a loaded gun setup along the KS/OK border with a down right impressive potential outbreak setting up across OK/KS if you believe the GFS. 5500+cape, very long curving hodos up and down the dryline just beautiful looking really, upper level energy arriving at just the right time of day. This might very well be a serious severe weather event.

 

[samuel stone]

2011-05-24 FCST; KS/OK/TX

still considerable spatial differences for tuesday between the NAM and GFS mostly with the GFS being further north and a little west with the surface low. However Both models are looking good for a number of tornadoes in sc ks/nc ok. The NAM progs the triple point right over the ks/ok border I-35 intersection by 0z with mouth watering EHI values along the tp and warmfront which drapes east along the border. EHI values of 3-6 at 1km and 6-10 3km at the tp by 0Z! with a potent upper wave pushing through at the right time, plenty of CAPE well in excess of 4000 j/kg, a beatiful wind proflie all the way up to 250mb(finally some descent velocity at that level) as well as low enough lcls im getting excited. now lets see if the models begin to agree on the placement and other smaller details in the next 24 hours.

thoughts??

lets start gettin this Target area back to what it used to be i know theres fcsters on here that can lend more insight than me

 

[Tim Supinie]

A quick look at the NAM forecast is, indeed, a little scary. This model sounding in particular gets my attention: http://bit.ly/j1oXVW . A hodograph that looks like that (0-1 km helicity near 200 m^2/s^2 and 0-3 km helicity near 300 m^2 s^2) with CAPE that looks like that (over 4500 J/kg) smells like trouble. I'll end up doing a more in-depth analysis tomorrow night, but from where I sit right now, if I can only go out one of the next two days, it would be this one.

EDIT: BTW, this should probably be moved to the Target Area forum and combined with the thread that was just started.

 

[Michael Riedl]

This has the potential to be a very dangerous day across the Central Plains, probably synoptically the best set up since April 27.

The NAM and GFS still differ on a few things, surface placement of the Surface Low and associated dryline and as well as the orientation of the LLJ. EIther way the NAM has been showing EHI off the charts on Tuesday.

Some things of concern that the GFS has been showing is a mid level dry punch coming in in the norther parts of the dryline in Central KS. Showing an area of 65 Surface Dews with 0C 850 Dewpoints, not too good.

Confidence is growing in a potentially dadngerous day tomorrow, with plenty of chase opportunities.

 

[Mark Blue]

The FCST thread for 05/24/2011 was merged with another FCST thread that was created outside of the Target Area, which is not in compliance with the forum rules. I have merged those two threads and cleaned them up and the Administrative team will be in touch with the members whose posts were deleted. The posts that contained valid forecast material were left intact, however, the posts that did not were deleted.

Please take a moment to review the updated rules for posting TA threads so you are familiar with the changes here: Target Area Rules.

 

[Patrick Marsh]

An inferred strong PV anomaly (short-wave trough) is moving east across southern California as depicted on this evening's water vapor imagery. To the south of this short-wave trough, a cyclonically curved mid- to upper-level jet appears poised to spread over the central plains in the next 18-36 hours. The airmass In the central US is characterized by deep boundary layer moisture (mixing ratios between 13-16 g/kg on evening soundings) and very steep lapse rates of 8.5-9.5 C/km. Every method of characterizing tomorrow's severe weather potential places this in the classic tornado outbreak category. In fact, the last time the central plains had this rich of boundary layer moisture beneath this kind of (forecast) wind field could very well be 26 April 1991. Another potential analog (for instability and shear) is the 13 March 1990 outbreak. Rather than continuing to post what is "right" about tomorrow, it's probably easier to talk about possible failure modes.

1. My biggest concern is that mental extrapolation of the current PV anomaly in southern CA brings it out over the southern plains rather early tomorrow (~18 UTC). Boundary layer theta-e and steep lapse rates will still yield an extremely unstable airmass early in the day, coupled with strong rising motion from the ejecting negatively tilted short-wave trough during increasing and peak diurnal heating should help to erode the cap quickly. This could tend toward fairly quick upscale growth.

2. Also, I am a bit concerned that the wind fields don't maximize until near/after dark. These "smaller" hodograph could lead to splitting storms early (before enlarging and decreasing the potential for surviving left splits) that interfere with other storms, also tending toward upscale growth. (With that said, the early hodographs aren't anything to sneeze at.) Although I'm not explicitly forecasting one, it wouldn't surprise me to see this organize into a strong derecho as the evening progresses.

3. What impact will residual outflow boundaries from ongoing and overnight MCSs have? What about possible cloud cover? The cloud field with the ongoing MCS across NC/NE OK is still expanding/developing WSW...

Again, this is a pretty classic severe weather setup. These are just some of the potential failure modes I'll be watching tomorrow.

 

[Michael Riedl]

This is continuing to look like a dangerous situation. A forward propgating MCS looks to form in NW KS tonight and the move eastward tonight and into early tomorrow morning, there should be a cloud layer over SC KS but we should be able to clear it out. The shortwave is perfectly timed to come across an extremely unstable (3000-4500 J/kg CAPE) warm sector. The 0z NAM shows the area from US 50 near Hutch to US 412 near ENID to be what I consider to be the highest threat area. Hodo's in this area are borderline scary as the LLJ really starts to scream at 0z tomorrow. This will cause 0-1 KM Helicity to be nearr 300, and potentially even higher as it seems in recent weeks the models have been underestimating Helicity (joplin tornado had 400 SRH at the time of peak intensity, don't remember that being forecasted).

The dryline is in an unfavorable position when it comes to being near populated areas, so hopefully we don't have to deal with that tomorrow.

Some things I think worth noting, the Models have been consistently showing an area of weak 850 Dewpoints in the warm sector in KS, so this is something to keep an eye on as the morning turns to afternoon tomorrow. This is one of the main problems I have with areas north of Wichita tomorrow. I also don't like the weak Mean Flow from 500MB up in that area. The NAM is almost showing 240 degrees of turning in that area as well.

So all in all fairly confident in the dryline/warm sector producing almost everywhere, however the maximized area should be between US 50 and US 421.

The 0z NAM has shifted things a little further east than the 18z NAM had with the dryline almost on top of I-35 tomorrow, however it shouldn't make too much of a difference wise other than shifting the target area towards more unfavorable terrain.

Will probably target Wellington as an initial target.

The triple point is in play tomorrow as well, but there are plenty more issues there than along the dryline.

 

[Trey Thee]

Well tomorrow is definitely looking potent. I hope my doctors appointment is on schedule and done quickly...

Patrick, I have a similar concern(s) I am wondering what sort of impact the current convection and convection after midnight will play on the system. Additionally, will cloud cover move out quickly or will it stick around? The growth could go upscale quickly, we've seen moderate and even high risk days bust for similar reasons the last few years.

Having said that, the potential with this system far outweigh the negatives in my book. The 00Z NAM has increased the instability by a fair margin over prior model runs, trending more towards what the forecasters have been saying. Helicity, shear, etc are all classic as you said. Additionally, the threat for tornadoes will become even greater as we approach early evening and will remain quite potent through midnight (assuming of course it doesn't go upscale too quickly as you pointed out). forecast soundings look impressive from 4pm onward as do the HODO's. It really looks like a solid setup.

Another issue we shouldn't lose site of is the potential hail threat. Which looks pretty monumental tomorrow.

I believe we'll have both OKC and Tulsa under a significant risk of SVR weather tomorrow and I expect to see a high risk issued on the Day1.

 

[Bill Schintler]

Chase targets for Tuesday, May 24:

Tuesday will be an active day over a large region, with both a warm front and dryline providing the focus for severe convection. Below are three specific targets, each of which should yield tornadic storms.

1. Seward, KS (9 miles south of Great Bend). Storm initiation: 3 PM CDT.
2. Perry, OK. Storm initiation: 4 PM
3. Wilson, OK (12 miles west of Ardmore). Storm initiation: 4:30 PM

Discussion:

ST and SC will blanket much of the western half of KS through late morning. Storms, primarily elevated, will initiate by early afternoon over northwestern KS and adjacent areas of northeast CO as strong synoptic lift overspreads the area where mid- and upper-level temperatures are coolest. H7 temperatures will fall to 5C by 18Z with the approach of the upper system. Convection will then fire from west to east along the outflow-enhanced warm front 40 miles south of I-70 between 2 and 4 PM CDT. A warm front/dryline triple point located near Great Bend at 21Z may provide a local focus for convection. Storms forming along the warm front will move towards the northeast at 20-30 kts over to the cool sector, however sufficient surface-based instability will exist there. Extremely large hodographs will be in place along and north of the warm front as a 45kt southwesterly LLJ surges over backing surface flow. Low cloud bases of 500-750 m AGL will greatly enhance tornado probabilities, at the expense of storm visibility.

Further south, isolated supercells will develop along the dryline along I-35 in OK between 4 and 5 PM. LCL levels will be somewhat higher in OK, ranging from 1000 to 1200 m AGL east of the dryline. However, deep-layer shear and CAPEs will be corresponding higher. SFC-6km shear may locally exceed 80 kts as the H5 streak overspreads southern OK. CI, associated with the upper system, will spread over western KS and the TX panhandle by 21Z; however, this cloud shield should remain sufficiently west so as not to impact insolation along the dryline.

Bill Schintler
KD0DJG
10:55 PM CDT, 05/23/11

 

[Mikey Gribble]

I am ready to hit the sack so I'm just going to copy and paste from my blog. Tomorrow looks like a classic plains tornado outbreak setup. The thing that has me particularly concerned is that the dryline is setting up about the perfect distance from Wichita (and other large cities along I35, but especially Wichita) for storms to really be cranking and tornado potential to peak as they get there. If we get discrete storms off the dryline tomorrow, this could be a very bad deal for parts of Kansas and Oklahoma.
Good luck if you are chasing tomorrow. Below is copy and pasted from the last blog post I made...

I think I’m going to target the KS/OK border tomorrow with the intention of getting on a storm firing just south of there a ways. I am a little worried about 500mb winds backing too much farther north into central Kansas and I’m a little worried about low level shear not being quite as good as you go farther south (northern portion of dryline has much better curvature in hodograph). The border area seems like the best compromise, plus the NAM has the LLJ being at its strongest right there. Storms developing in this area will track through very strong instability and will encounter stronger low level shear as it moves north (because of backing winds and low level winds strenghtening towards dark). Any discrete storms in this area will almost certainly be tornadic and will likely produce strong tornadoes.
As I mentioned before convective evolution is obviously one of the big things that could scew us tomorrow. I don’t think it will be a problem though. If the trough had a little harder negative tilt to it I’d be more worried. This trough is that perfect neutral going into negative tilt that you like to see for tornado setups. It really looks like a classic plains tornado outbreak.
850mb winds are out of the south at 50kts with the NAM right along the KS/OK border by 00Z. That is pretty damn impressive with SBCAPE >4000J/kg in the same area. Any time you get backing 850mb winds that strong it should be a huge red flag for tornado potential. I would even go as far as to say that violent tornadoes (EF4-5) are a real possibility tomorrow. I would go high risk with a 35% hatched tornado probability for north central Oklahoma and south central Kansas. I’d go moderate with 15% hatched over the southern portion of the dryline.
I will update again first thing in the morning.

 

[Eddie Natenberg]

Ok after deleting my first post (go me) lets try this again.

In reference to the PV anomoly that Patrick mentioned, the RR has picked up on that and shows some increased VV by 20 UTC and shortwave ridging downstream from this feature. I worry about too much forcing along the dryline too early but the RR seems to only break out convection by 21 UTC in CHK even with 5000+ cape and CIN being erroded by 18 UTC (actually all the model show quick cap erosion), with such strong focing high SREH and shear are needed to maintain discrete storm modes. But I think with the decent pressure gradient shear won't be an issue. The models are also trending the dryline west as with the latest RR, so I expect this to be a central OK event up to ICT. I am worried that with such little cloud cover and strong mixing LCL will be quite high until the LLJ kicks in.

All in all I think tomorrow looks pretty classic, but to forecast storm mode and interactions I will keep an eye on the local profiler and vad data, since themodynamics will not be lacking. I hope any discrete cells can stay in sparsly poplulated areas. I expect a high risk at 06 UTC with hatch TOR risk from ICT to DFW.

 

[samuel stone]

my target will be kingman to wichita along US-54 with the possibilty of heading down towards the anthony or south haven area. EHI values will be maximized in this area reflecting the best compromise between low level shear an instability, get any further north from there and i start to worry about mid level backing and weak upper level velocities as mentioned above. pretty much agree that early initiation and storm evolution are the primary concerns.

overall. weve been waiting for this for far too long in sc kansas. (the models have been loving sc ks this year and have yet to verify) and the general public should have a plan in place for tomorrow many schools in Hutch have field trips planned to wichita tommorow my mom works for the district

 

[Jeff Duda]

I was originally targeting the KS-OK border area south of Wichita for the best ingredients that are within a reasonable drive for me. I've become very concerned over what I've seen from the models since last night. The GFS is showing this especially: backing 500 mb flow over both KS and OK. Thus, deep layer shear really suffers, as there isn't much acceleration or turning above 700 mb. This tends to favor a mix of discrete and linear storm modes, which are being reflected in all of the high resolution output I've seen in the last 12 hours. I have only seen one high resolution model put discrete storms north of the border. All other high res models are progging a cell to develop around Medicine Lodge and quickly become linear by 00Z. I'm also concerned with the cluster of elevated t-storms currently moving east across W KS. Although pretty small in scale,this cluster is moving E/ESE and could strongly restrict the northward extent of the warm sector. This would put the best warm sector right over the Flint Hills region of SE KS/NE OK where road and data networks are horrid at best.

 

[Jeff Snyder]

I had been thinking about a target in extreme S KS, largely because it's very difficult to deployment radars in Osage county and adjacent portions of Pawnee county, and the road network in the Flint Hills area of southeastern Kansas can be difficult at times. The 12z RUC is slower with the dryline, and indicates the potential for high-end tornadic supercells through the Red River region as well, where slightly less back 500 mb flow looks to provide stronger deep-layer shear. Although it is forecast an "end of the world" situation (>6500 j/kg SBCAPE, <750 m SBLCL, 350-400+ m2/s2 0-1 km SRH, etc.), it's forecasts of moisture are too high. In much of central Oklahoma, the 12z RUC valid 00z (fcst hr 12) has >75 F Tds, which will end up being at least 5 F too high based on upstream surface observations and 12z soundings. Both the OUN and FWD soundings sampled a 15-16 g/kg mean mixing ratio in the lowest 1 km, and current observations show 67-71F dewpoints across much of the moist sector. The overforecast of moisture on the RUC results in an overforecast of CAPE and underforecast of LCL. However, these will still be in a relatively unpopulated portion of the parameter space. We just don't see this combination of CAPE, LCL, deep-layer shear, and low-level shear very often.

The 12z OUN sounding is quite capped, with a >90 F convective temp, FWIW. Depending upon what the 18z soundings regarding temperatures at the base of the EML (which will give us insight into residual CINH), I may end up eyeing central Oklahoma instead of my originally-intended target farther north.

I'm short on time right now, but I'll try to provide an updated forecast (since the above isn't much of one) a little later. Starting in the OKC area, I don't think I need to blast out of here very soon.

EDIT: 12z NAM trended westward, which does fit with observations relatively well. It's not as gung-ho as the RUC (this it typically the case), and it shows QPF in southwestern Oklahoma 18-21 z. This is looking more like a western and central Oklahoma chase, IMO, with uncomfortably-backed 500 mb in Kansas. Again, I'm starting from OKC, so, if the conditions looks similarly good over a relatively large area, I'm might as well target something closer to my current location.

 

[Ryan Pfannkuch]

Been awhile since I chased a setup that looked this "scary" on paper...starting the morning in Enid listening to the jets flying over every few minutes.

4-county target area in north central OK: Garfield, Noble, Logan, Payne

Not going to delve too heavy into the parameters, as we all know what they are. Also agree with Jeff that the backing mid level flow per the 12z RUC could pose some convective mode issues, as forecast sounding for Enid exhibit at leat a hint of the "S-shaped look". Of course, the low level shear is off the charts.

I think the biggest challenge on days like this is just where to go, north vs. south vs. middle? Focusing on the best perpendicular crossover of the H5 flow across the dryline, part of me wants to drop down to North Texas, although that puts the Metroplex into play and don't feel like messing with that today. This whole north vs. south decision drives me crazy on days like this, and my plan for now anyway is to play it simple, and just stick close to where I am waking up this morning (Enid). With parameters looking this good overall over such a wide area, I think it's just a wait and see, as we are ultimately at the mercy of storm mode evolution. This wouldn't be the first time that I drove 100+ miles away from where I started the day only to have a good storm roll right through the wake-up spot. For now I'm content to stick with the 10+ RUC-progged EHI that I have right here. For whatever reason, I just don't have the usual motivation to wander north into KS and get on the warm front/outflow boundary. Maybe that will change in 4 hours...that's chasing.