5/23/10 FCST: KS/NE

[Brian Stertz]

Pretty favorable setup tomorrow for supercells and a few tornadoes after about 5pm across NC/NW Kansas into SC/SW Nebraska and possibly northward up to the I-80 corridor. The 06z NAM has a boundary sagging south and then holding up stationary along or just south of a GLD-HSI line. Strong instability (at/above 3000 j/kg CAPE) and pretty good LL shear 200-300 ESRH exists along/north of the boundary ...with good warm/moist air noted on both sides of the boundary. There is also some hint of a mid level wave moving n-ne into the frontal boundary zone by early evening. This should erode the cap for a cluster or two of supercells to fire...particularly in the Hill City-Phillipsburg KS area. Setup looks worthy of a chase out west, and initial target will be Phillipsburg KS for tomorrow.

 

[Dean Baron]

I also like Phillipsburg. Was originally thinking Hastings, NE but looks like the cap will be stronger in Nebraska as per forecast soundings. Right along that bounday should be a favorable environment for a couple sups with as Brian mentioned strong to extreme instability. Helicities are best right along that bondary and forecast soundings and WRF show CINH breaking down by 21z over north central KS and by 00z across south central NE. I will stick close to the KS/NE border and take Phillipsburg, KS as well.

 

[Chuck Robertson]

Yes, Sunday has recently caught my eye, especially in NW to NC KS. Latest NAM from this morning improves the T-Td spreads over earlier runs. However, one potential problem may be the weak winds at 300mb and up. Other than that, the setup looks quite favorable, and am considering a jaunt up in the direction of Hays tomorrow morning.

 

[Logan Karsten]

I too like this setup for several reasons. First, CAPE along and south of the boundary is rich and plentiful. Secondly, storm motions will take the storms along the boundary so they can tap into the good helicity along the boundary. Thirdly, storms won't be going 40-60 mph as with some other chases this season. Also, I love the chase terrain in south-central Nebraska. However, it's worth noting the 12Z NAM has shunted the boundary further south than previous runs way into northwest Kansas. This may push my target further east towards the Lincoln area. I don't want things to get to far east because then you will get away from the better shear. A northwest Kansas target close to the dryline would also be pretty good, but that's too far for me, at least for now.

 

[Eric Bucsela]

NAM has really been lowering the instability the past couple runs. The 12Z 4km WRF does not break out any precip in the area through 00z. But the 18Z NAM does show initiation in W KS. Also the GFS is still impressive with a large area of CAPE > 4000 on the KS-NEB border. Not sure what to make of it all.

 

[Logan Karsten]

What's concerning me now is there is a displacement between kinematics and thermodynamics. Also, NAM has shunted the boundary further south than earlier runs. I may reconsider driving that far now for a marginal chance of seeing anything.

 

[Andrew Stoller]

Yea, the RUC has the triple point way further south now into southwest KS/southeast CO. Still fine IMO, as any cell firing there will ride the front to the northeast. I guess the key today is to keep an eye on exactly where the triple point ends up as that is where the RUC/NAM has been breaking out precip, even on runs where it was further north. I'll probably target Goodland and keep an eye on surface features closely.

 

[Brian Stertz]

Today looks to be quite promising for tornadoes along the slowly lifting boundary by early evening across W. Kansas. Today looks to be a setup that involves strong LL shear along/north of boundary versus identifiable strong upper support. Right now there appears to be a good tornadic supercell threat along/north of a Sharon Springs KS to Ness City KS to Larned KS line by early evening. My early target will be Hays KS with adjustments from there. With over 40 kts. of 0-1km shear and an e/w boundary with adequate instability, this one could open up to be a clustered and pretty well focused tornado event...tornado intensity TBD.

 

[Chris Hayes]

Sitting in Grand Island, NE and the cold front moved through in the past hour marked by a band of low clouds. Am probably just going to head to northecentral to northwest Kansas along the I-70 corridor and wait and keep an eye on where the warm front is. Already plenty of instability across a large chunk of Kansas with CAPE approaching 2000. NAM places the best instability in eastern Nebraska but with a very strong capping inversion at the same time. Weaker CAPE but still enough to get the job done will be in NW Kansas. Not very strong helicities in the 0-1km level though. Hopefully the warm front will provide enough low level support to drop a few tornadoes. Hope to see everyone out there.

 

[Ryan Pfannkuch]

Sitting here at home in Hastings NE, taking an extra close look at today after passing on yesterday's tornadofest in SD.

Fortunately, it seems today's focus area for late afternoon/early evening inititation seems to be getting more clear-cut with time in the short term model world (time will tell). Both the 0z EMC 4km WRF-NMM and the 12z HRRR point to the general west-central KS area, with potential for severe weather rapidly shifting north into NE toward dark and thereafter.

Agree with Chris from 12z RUC soundings that low-level shear not overly impressive, with 0z 0-1km shear at Hays only 16kt, but with an increase likely thereafter as the LLJ cranks up. At the sfc, the E-W boundary stretching east from the SE CO low looks favorable.

preliminary 4-county target area in west-central KS, on the western edge of the CAPE "max" and along lifting warm front: Trego, Gove, Ness, Lane

 

[Chris Hayes]

I personally think the NAM is out to lunch with it's CAPE forecast. 1700z mesoanalysis shows a large area of SW/SC KS having 3000-4000+ SBCAPE already. The RUC might not have been too far off with it's CAPE forecast. Forecasting 6000+ it might be a little high, but I think it'll be higher than the 2000 or so the NAM is predicting for western KS. Just need to get the warm front moving north. Target is still Hays to Wakeeney and monitoring from there.

Edit: Both the 12z nam and most recent RUC run both break out precip over KS. Most recent RUC shows a fairly large area of substantially weakened CINH over KS and NE. Stay safe everyone

 

[Logan Karsten]

I would agree that western Kansas looks to be the good play in town today. Especially towards 00Z as the LLJ kicks in and really cranks up the shear. Good luck to everyone.