2018-05-01 EVENT: OK/KS/NE/IA

[Brandon Centeno]

The first of a pair of very intriguing days is set to occur on Tuesday. Unlike the day before it, Tuesday will have adequate moisture in place for a severe weather event. Slight height rises and implied subsident large-scale vertical motions will likely make this a borderline conditional target, however, with southwesterly flow aloft, smaller-scale perturbations in the mean flow could certainly aid in storm development.

The greatest threat in terms of discrete supercells capable of tornadoes looks to be in NW OK into southern KS, thanks in part to a strong low-level mass response and developing low-level jet in the afternoon/evening hours. Instability in the 2000-3500 MLCAPE range owing to upper 60s dewpoints beneath steep mid-level lapse rates will be conducive to rapid accelerations for any updraft able to sustain itself. Strong vertical wind shear in the low- and deep-layers will promote supercellular organization, with tornadoes possible. Coverage will remain quite low due to lack of broad large-scale ascent. So while a cap bust certainly is possible, I find it hard to believe we will not see at least isolated supercell development along the dry line in Kansas or Oklahoma.

Elsewhere, stronger/linear forcing will likely yield scattered supercells before upscale growth occurs. A tornado or two probably can't be ruled out farther north/east along the front.

Looking forward to a solid chase in great terrain. My entire week is clear after 715 am Tuesday, so I'm really looking forward to getting back out there. Currently, thinking I'll pass my fitness test at 615-715, get some breakfast, link up with another ST'er and head for the Woodward area or a little farther north.

 

[Brad Dormer]

Depending on how early I can get out of the hospital, this may be my first chase ever, probably either up north hanging around the front or down along the NE/KS border not any farther south due to time restrictions, overall, I like the way it looks for southeast NE, right now, it looks like there will be sufficient moisture and surface winds will be slightly backed, along with 0-6km bulk shear values increasing to 40-50kts and CAPE around 2500 j/kg, hoping the trend will continue, but not too sure, either way, I'm hoping tomorrow will be my first "real" chase that actually involves leaving the house. Good luck to everyone else that will be out there!

 

[Jeff House]

Tuesday I favor just east of the triple point TP in north-central Kansas. One could also target the first or second cell down the dry line DL. Just east of TP should have slightly more low level backing. TP position could change with overnight convection. Fortunately Monday night MCS is not forecast to be a beast/wash-out, but always worth watching.

Heights may be neutral or even slightly rising Tuesday. However it is not a show-stopper with shortwaves ejecting out. Were heights rising on the Chapman day? NAM might be too moist though; and if so, farther south on the DL might be favored. Still, I love boundary intersections. TP or outflow/DL looks best with locally backed low level winds. Current TP forecast is north-central Kansas.

 

[Royce Sheibal]

Prepare for your mandatory warm front play discussion from the Nebraskan.

GFS, NMMB, EURO. All loving the NE/KS border up onto the warm front. Mega HP TP Super cell likely according to CAMS along the border or just south. But...Indexes really spike up near and west of Omaha by 7pm, down toward near Hebron, NE. Cap should gone and lots of coverage possible. Low level shear nearing 40kts. NAM 3km is having issues resolving the storms outside of the TP. Conus HD having no issues but splits the gap with TP and NE Neb getting the action. Feeling confident that the WF play will work out and will have minimal chaser convergence, and that chance of total bust is low.

Downsides: PWET approaching 1.5 so HP possible, lots of coverage and numerous embedded cells likely. Giant Hail. Could be a messy day. Lots of R/L splits and deviant storm motions on CAMS.

My target: Crete, NE, with possible detours SW to Hebron or whatever pops on the WF, meaning LNK and OMA could be in play for serious problems, neither area being remotely chasable either.

P.S. Enjoy the plays down in KS, but if i could, I'd be down in SW OK where things will be more isolated but still has quite solid dynamics. Woodward to Elk City looking fine.

 

[samuel stone]

To me it looks like triple point or dryline play. there has been consistent and solid guidance suggesting robust development at the triple point fairly early in the day (21z possibly before). That tends to hinder the tornadic potential of WF (frontal zone) convection immediately northeast of the TP. If early TP convection is as robust as projected.

I don't mind the rising heights (as Jeff mentioned) convenction looks likely near the triple point and storm motion is in a favorable direction with respect to the WF to allow it to ingest warm, moist, and undisturbed backed flow for a decent window before possibly merging into a large rotating cluster. I have been impressed largely by the consistently clockwise hodographs (with little VBV) produced by the NAM in north central Kansas and southern NE.

At this point I am targeting just east of the TP. The 3km NAM has been consistently further south with the TP, we will see what the HRRR and the RAP do with it.

 

[Ethan Schisler]

I will be out chasing tomorrow for sure, probably somewhere around Great Bend to Salina, KS. I'm not too thrilled about this setup, but considering its my only two days off for a while and there hasn't been much lately and the overall pattern looks bleak....I will bite. I think the fail mode for tomorrow will actually be moisture. 00z data doesn't really lend much to my concern, however experience with this area being in a substantial drought (extreme or greater) and moisture in the panhandle today generally being less than models showed, I think its reasonable to think that models could be overdoing it tomorrow. HRRR (latest run going out to 3pm tomorrow) lends credence to this showing spreads on the order of 20-25 degrees in the target area with dew points only reaching the lower 60s and temperatures surging well into the mid and upper 80s with quite a bit of mixing occurring. This isn't good for tornado potential as most of us know. I will probably keep an eye on the front and try to stick somewhere close to that and see what happens. I'm expecting a similar outcome to the chase in Iowa a few weeks back on 4/13 honestly. Few storms to be marginally tornadic early on and then mainly hail and wind. We will see I guess, I hope I'm wrong....cheers everyone and happy chasing!

 

[Quincy Vagell]

Today looks like a scaled down version of 5/6/15. It even shows up as a top analog via CIPS. The two main differences are weaker large scale forcing and more capping with southward extent.

The two most obvious targets would appear to be a triple point in central/north-central Kansas and the dryline in south-central Kansas. Both areas have pros and cons. Convective initiation is all but certain near the triple point, but storms may merge and/or get messy quick. The dryline farther south should feature more isolated storms, but there is some question about how much sustained convection can fire, especially with southward extent.

Boundary layer moisture looks much better than yesterday, but still not ideal for a higher-end event, as mentioned by SPC. Still, it's encouraging to see 60F dew-points as far north as the Nebraska border as of 14z and 62-64F dew-points are common as far north as I-70 in Kansas.

Tornadoes are just about certain today, but only time will tell how the event performs. Good luck!

 

[Dean Baron]

Personally, I think the best bet would be to set up south of the triple point. Models are in pretty good agreement with placing the triple point along the Nebraska/Kansas border this afternoon. However, models are also in pretty good agreement in breaking out a lot of convection in the vicinity of the TP, which would make things quite messy. If this actually pans out, I think the best option would be to target farther south into central KS where models show the convection getting more isolated with the potential for a tail end charlie on the south end of the line of storms firing off of the TP. There may be a small window near the TP for storms to do something, but it looks like once the cap breaks, things will go up quickly and storms may be competing against each other. HRRR still shows a few nice helicity swaths in this area, but it will probably be embedded and difficult to see/chase. If I were chasing I think I would be targeting somewhere between Russell and Pratt, KS for now.

 

[Jeff House]

Initial target is central Kansas with an option to drop to Medicine Lodge or Protection. Great Bend and Hutch have great road direction options for after a relaxing sit-down lunch and nowcast.

Almost always easier to adjust south vs north considering storm motion. Therefore target is triple point first; then, dry line if/when TP becomes messy.

TP and just east of low/mesolow will enjoy more backed low-level wind. Also less risk of moisture mix-out. However TP has more risk of multiple cells interacting and/or crossing into the cooler sector. Figure a cell just east of the TP can manage a cycle or two.

Low level winds ahead of the DL are less backed. However cells will be more isolated. CAMs forecast a beast or two down there. Could just be gorilla hail, but if dews keep near 65, maybe tornadoes.

Bottom line: I would start in central Kansas, with the option to drop south. Since Wed looks better now, it takes a little pressure off today. Have fun and chase safe!

 

[Kelton Halbert]

Violent Tornado Parameter (VTP) beginning to increase in west-central KS, and should both move east and increase in magnitude as the afternoon rolls on. Starting to get some very strong 0-3km MLCAPE, which can be indicative vortex stretching potential by an updraft (more info on VTP and 0-3km CAPE can be found here). Dewpoints also looking pretty decent per the most recent RTMA - I'd probably be situated in Salina if I were out right now.

 

[Jeremy Bower]

Took a look at GOES-East and you can clearly see cumulus clouds developing along the dryline in SC and SW KS into the OK panhandle. Mixed layer CAPE value already up to 2500-3000 J/kg in C KS. I concur with what has already been said above. I think the play today would be a little south of the triple point out in front of the approaching dryline. SPC Mesoanalysis shows a dewpoint currently of 65 at Salina and that is probably where I would position myself today and watch the storm evolution carefully. This could be one of those days where you wait until just an hour or so before sunset for tail end Charlie and hope the magic happens.

 

[David Rundle]

Looking at KDDC in clear air mode on RadarScope. There’s a distinct boundary moving into the moderate risk/ MSC area. Believe the dryline is ready to go...


Sent from my iPhone using Stormtrack

 

[Mike Johnston]

"Looking at KDDC in clear air mode on RadarScope. There’s a distinct boundary moving into the moderate risk/ MSC area. Believe the dryline is ready to go... "

Exactly right...you can clearly see it on radar.

The overall radar picture, together with the latest mesoanalysis readings, suggest a target of Harper, Kansas.

 

[MikeD]

CAPE at 2300 and wind shear at 50 knots in north Kansas. These Nebraska supercells don’t look LP to me. More of Wet-classic.

The border between Kansas and Nebraska is the best place to be right now. The supercell that is Northwest of Omaha is developing a strong hook echo. I wouldn’t be surprised if a debris ball spins up on radar.

 

[Warren Faidley]

Storm east of DDC is about to move into a highly unstable area with supercell index of 12 / much higher SR helicities and RH. It might get interesting shortly in that region.