2012-04-27 FCST: KS/OK/MO

[Adam Simone]

I'm surprised there isn't a thread for tomorrow yet. To me it looks much better then today's setup. CAPE values over 2,000 should extend northward to almost I-70 with 1km SRH over 200 throughout most of Eastern Kansas. Just looking at the forecast sounding for Emporia, KS at 7:00pm tomorrow night it looks good. CAPE over 2,300. 1km SRH of 259. 1km EHI of 3.8, and LCL Height of 760. There isn't much of a cap so my only concern right now is the storms could become clustered instead of isolated but I'll take my chances. Tomorrow definitely looks like a decent chase day to me but not getting my hopes up just yet.

 

[Skip Talbot]

The models have been flip flopping and disagreeing with each other on the placement of some surface features and what the low level jet is doing. Even at 36 hours out there are still some differences between the NAM and GFS on the placement of features and orientation of the LLJ. Differences aside, both agree on what looks like a favorable chase setup across eastern KS, eastern OK, into Missouri. I won't repost the above cited parameters, but they're more than sufficient to support supercells given large curving hodographs and moderate instability. The cap weakens most, 0-3km instability is greatest, and the midlevel flow is strongest across southeast KS so I'd probably focus on that area for initiation based on the 12z NAM. Or just southeast of the triple point allowing for the shifting surface features and flip flopping models. The low level jet is forecast to ramp up at dusk, enhancing helicity values away from the warm front. That's when our tornado threat should peak while instability remains decent.

A few concerns: warm sector junkvection is being plotted on both the NAM and GFS given strong warm air advection and the early arrival of lift from that broad midlevel flow. This will limit instability along the warm front. The NAM was hinting at a 700 mb dry punch along the KS/OK border. That may clean out the clouds in the afternoon allowing for destabilization. The winds back best closest to the triple point, however. So I think this going to wind up being a balancing act of playing where the instability gradient overlaps the better directional shear. If that junkvection doesn't clear out, this is going to be a much more marginal setup pushed south where directional shear and lift are weaker. The GFS has also been showing 850's that are veered pretty badly although they aren't too bad on this latest run. It's a bit sloppier with surface features, with what looks like a retreating dryline. Lift south of the triple point might be an issue as a result. Another concern is timing on shortwaves troughs/upper level disturbances. The broad midlevel flow makes for good speed shear, but it's waning by 0z. We need a well timed disturbance to get the lift we need to initiate afternoon storms when the cap opens up.

I'd try to play as close to the east central KS triple point as you can where adequate to moderate instability is still realized. Your directional shear will be greatest there. Your best shot at a tornado will be in the early evening when that low level jet ramps up and cells move toward the warm front. I wouldn't expect this to be a huge event, but a couple cells in the warm sector could put down tornadoes so it could make for a great chase day.

 

[Rocky Rascovich]

I blew off today (4/26) in favour for this day in C. & E. KS. probably targeting EMP and working my way eastward. I am concerned as Skip illustrated, ongoing convection earlier in the day, it will depend how much of this can clear out, destabilization rates, the gradual veering of low level flow.. etc. If all these potential negatives can be overcome, I think some classic SUP's with a couple of confirmed tornadoes will be likely. I'm strongly considering a chase tomorrow unless the potentials back off from what's currently forecasted and head up toward EMP and reevaluate from there.

 

[Ben Toms]

I want that triple point to work oh-so-bad...and if everyone and their dog goes out to chase the dryline bulge/WF play in SE Kansas, I might just have to make it work.

In my opinion, tomorrow looks promising for isolated supercells along the massive dryline bulge in SE Kansas and possibly a warm front rider or two across east-central Kansas and into Missouri. I think the significant tornado potential will lie closer to the triple point if we can get enough surface heating and moisture pooling up there, but if not then I'll be waiting for the warm front interaction. Veered/southerly surface through 850 winds are an issue the closer you get the dryline, so I'd be looking for the locally backed winds. Outflow boundaries will definitely play a key factor in significant tornadoes as well. Anyways, I have confidence in there being tornadoes on the dryline storms away from the warm front, but if we're looking at significant probabilities I'm going to stick with the triple point/warm front or an outflow boundary/dryline intersection.

The real negative I see is if the shortwave kicks out in the early afternoon, but even if this happens we should still be able to get some storms to fire when it moves through. Capping is a bigger issue the further south you go, but overall it shouldn't play that big of a factor in completely inhibiting storm development since nearly every model has mid-level cooling happening during the early afternoon.

I'm hoping there won't be masses of people out since it's a Friday afternoon play and the SPC has been downtalking this one, but if it looks like there will be a thousand people out and only one dryline/WF storm, you can find me on the triple point.

 

[Rocky Rascovich]

As of 1400GMT, I sure like all the parameters I've seen based on the latest RUC and HRRR; everything with the exception of the cape values which I think may be the only hindrance to what otherwise would be a substantial outbreak across the aforementioned region, especially KS. Current satellite and radar trends don't look very promising for any kind of real clearing to allow for destabilization. Regardless, I'll be out the door asap, and heading up toward the EMP area and decide from there if my efforts were in vain or not. Despite the lack of good cape, the incredible low level shear and vertical velocities with the approaching system from the west will likely make up for the difference. Hopefully the warm front will stay close to or below I-70 as I don't want to get too far away from home, this is where I expect the greatest shear to take place. Hopefully my gamble will pay off.

 

[Eric Bucsela]

I agree with Rocky that SE KS, maybe near Emporia looks best. Chances are better there for adequate instability and backed 850 winds, and EHI values are quite nice. IMHO, the main thing that kept either yesterday or today from being "classic", was the timing of that shortwave. But today could still turn out great!

 

[Andrew Burnett]

Just looked at the 1400 & partial 1500 RUC. I am concerned about instability north of Garnett or Emporia. That run doesn't seem to push much instability that far north into the prime shear. maybe I am missing something. it looks like a line will form north of 35. Descrete play for me would be SE KS. I would probably sit on 400 at the hill by Fredonia and wait for some sort of initation about 2 or 3ish.

 

[Jeff Snyder]

I like almost everything about today. The primary "ugh" that I see is the early arrival (only 4-6 hrs early for me) of the mid-tropospheric vort max. At 18z, most of the models (supported by current water vapor imagery) agree on the leading edge of the vort max to be located near I35/I135 in central OK, shifting eastward to near the KS/MO border by late afternoon / early evening. The battle appears to be between the forcing for upward motion associated with the transverse circulation in the left exit region of the upper-tropospheric jet streak and the downward motion associated with the differential anticyclonic/negative vorticity advection behind the vort max. Looking at the 12z NAM, 15z RUC, and 13z HRRR (latest that was available when I looked 30 mins ago), the implied location of the convective precip at 00z is essentially along the MO/KS border. Even though decent CAPE and moisture is ahead of the dryline west of the border, the models aren't doing much with convective precip along the dryline by 00z, presumably the result of the passage of the vort max. My success rate in such situations is pretty poor. This is more my complaining about geography (I'd much rather be near I35 at 00z than along the KS/MO border) than the potential for tornadic supercell today, though.That said, it's *really* difficult to ignore the shear profiles today. The sampling of forecast soundings (gulp) that I pulled from the 15z RUC and 12z NAM are quite impressive across far eastern KS by late afternoon, with very large, looping hodographs. There is a signal for poor low-level lapse rates (12z NAM was nearly moist adiabatic from the sfc to 600-650 mb in places), so I'm not sure if a storm would ingest the very high-SRH near-surface air farther above the surface that still possesses decent CAPE. If we can get sfc-based storms, though, particularly if we can get some insolation to steepen the low-level lapse rates to further support surface-based convection, I think there could be some siggy tors today.

 

[Andrew Burnett]

Just reviewed the 17z.. Joplin area looks to get crazy right about dark with RUC showing a descrete cell in the area with EHi's over 10 and a CAPE pushing 3000. sfc to 500mb crossover is looking prime too.

 

[Mike Johnston]

Some type of boundary evident on ICT radar now, extending from roughly McPherson to Winfield. Don't know if it's an outflow boundary or some indication of the dryline itself. Anyway, looks like CIN is starting to erode over S Central KS now with instability building. A good point to station might be Yates Center, KS at the intersection of U.S 54 and U.S. 75.