2015-04-08 EVENT: KS/OK/TX/MO/AR

[Trey Thee]

I try and not get caught up in the hype of these type of setups until the system is actually on shore. With that said, Wednesday sure looks pretty good right now for tornadoes. Lots of instability, breakable cap, low LCLs, you name it. Seems too good to be true! I tend to question moisture and moisture depth on a lot of setups. I did check to see if the 18z NAM was initializing surface dewpoints and it did a pretty good job.

Thats a fair point, the system will not get fully sampled until tomorrow afternoon or evening is that right? That could throw a wrench into chase plans, but I have to say this setup and the general model agreement are impressive for this early in April.

 

[Kevin Rider]

Thats a fair point, the system will not get fully sampled until tomorrow afternoon or evening is that right? That could throw a wrench into chase plans, but I have to say this setup and the general model agreement are impressive for this early in April.

The 12z model runs Tuesday morning should start getting better data. It is pretty slow coming onto shore.

 

[Michael Snyder]

Thats a fair point, the system will not get fully sampled until tomorrow afternoon or evening is that right? That could throw a wrench into chase plans, but I have to say this setup and the general model agreement are impressive for this early in April.

Yes, the dynamics are there, its just a matter of timing and strength of the low, there is little doubt about the moisture available, things look promising. Im trying to get some time to match up real time data from Commercial Aircraft to the GFS 12Z run to see how it compares. I had a hunch yesterday this low wouldnt be as progressive as the models were showing, but I have no data to back that up just yet.

 

[Michael Snyder]

Well for what its worth 03Z winds are slightly weaker on the west coast in and around the bay area. I took data from 16,000' to 35,000 feet. I was comparing real time 03Z observations vs the RAP 02Z soundings. Cant wait until this thing makes its turn onshore, things will get a lot more clear, like they always do...

 

[Nate Weikal]

For now, central OK looks like the best area for chasing. The ingredients look the most robust in that region when it comes to strong, photogenic tornadoes. Triple point is a good tornado potential, but at the same time, like others said, this is tending to produce hp storms for now. That could change though, but if it doesn't, I'll stick in central OK.

 

[Kyle Soldani]

CAPE/CIN - 06Z GFS seems to push favoring ERN KS, only slightly more. SBCAPE values are pushing 2500-3000 on GFS and showing 4000 in some areas of the NAM. MLCAPE and MUCAPE on NAM are in agreeance WSW of ICT, again with values nearing or at 4000 J/kg. NAM and GFS indicate a pretty broad instability ahead of the dryline in reference to CIN values which is also good to see.



SIGTOR (DuPage) - Fixed layer sigTOR is is throwing around more agreeance WSW of ICT. Interestingly there's also some dabbles of enhanced risk along the I70 corridor near Topeka, somewhat where the GFS was beginning to push east - something to keep an eye on.



SupCell Comp (DuPage) - Again here the GFS favors the ERN portions of KS while the NAM is widespread throwing out areas of 14+.



EHI - I feel like a broken record, GFS again is showing a pretty marginalized area from W of Topeka down into NE-CNTRL OK. NAM is showing a pretty broad area of elevated EHI for most of SERN KS and into OK.



500mb Winds/Shear - Interestingly the GFS/NAM seem to be in the most agreeance with shear values for the day, all 55-60kts + for any area of interest. My main point here was they certainly agreed in the corridor W of ICT.

LI's - Pretty well as expected according to shear our LI values show pretty significant instability across the board, NAM topping out at -10 W of ICT and GFS with -10-(-9) again in ERN KS. GFS shows a bit broader dryline pushing essentially to the KS/NE border stretching between a line from Wichita to Emporia with triple point NE of Salina? (Somebody correct me if I'm interpreting this wrong, learning experience..).



Bottom Line - Here's my area of interest and Newton being my first play, from what I see currently. I like the road network out of Newton if for some reason I wanted to push back East but I can also book West to Hutch or further if necessary. Plan will be to hit the road early, arrive in Newton around 19z and keep checking HRRR/RAP/NAM/GFS up until 21z go-time.



Discuss!

 

[Royce Sheibal]

This setup reminds me of my first chase with UNL back in 2005. Strong Low with triple point deepening as its pushing NE into Neb. There were leftovers from the morning that had pushed into NE KS and SE Neb. The backside had cleared from LNK all the way to OKC, heating and shear where both golden. The far south side of the dryline stayed capped that day (as it may well this time). The triple point near Clay Center produce the 1st tor of the day, and dropped a couple more before it fell apart east of Beatrice, NE. There was a LOT of huge hail that day out in the warm sector, Manhattan and Salina both got rocked.

Stories aside, I feel that this setup will emulate that day. Best chance for TORs is along the triple point in Central / NE KS, pushing into the missouri valley overnight. The south side feels likes its gonna be capped, and the models are generally agreeing. That being said, the TORs up north will probably be hell to chase, so maybe the long-shot cap-breaking N OK target is worth while.

My target if I was chasing: Salina, KS.

 

[Mike Johnston]

Seems like the most favorable area for chasing will be in south central Kansas. The severe parameters are just too good in that area. Cap strength looks perfect; I am concerned about too much capping further south into Oklahoma. I would say hang out on the west end of Wichita and see what develops; could be out in the Kingman, Harper, Anthony area.

 

[Kelton Halbert]

With 2 days to go before the event, surface dewpoint observations seem to support the threat. Mid 60s dew points have made it into central Texas, with some near-70s to 70s F observations lining the gulf coast. All in all, not looking too shabby. However, I decided to investigate moisture depth, and this has me a little bit concerned...


The satellite-derived total precipitable water vapor shows that the gulf has meager values of PW. Pulling up the sounding for CRP supports this information with the dry layer right at 850mb.



This brings up concerns for moisture depth quality for Wednesday, more specifically, how much those mid 60s F DPs will mix out during the afternoon. Either the depth of the moisture needs to improve a little bit more over tomorrow and Wednesday morning, or the surface moisture advection need to be enough to offset any mixing that takes place.

I'm actually pretty optimistic about Wednesday. This isn't trying to take a dump on the potential, because there certainly is potential! This is just going to be something I'm watching before picking my target area...

 

[Mike Marz]

Well, the 12z NAM is definitely pointing towards the Wichita area with a triple point storm, and it is not showing anything being able to break the cap further down the dryline.... I hope this changes, otherwise this may be an El Reno like situation where the models only depict one area of initiation that turns HP and every chaser out there is on that storm.

 

[Kelton Halbert]

Well, the 12z NAM is definitely pointing towards the Wichita area with a triple point storm, and it is not showing anything being able to break the cap further down the dryline.... I hope this changes, otherwise this may be an El Reno like situation where the models only depict one area of initiation that turns HP and every chaser out there is on that storm.

Remember that the NAM is not a convection resolving model (unless you are looking at the NAM 4km). At 12km, it relies on a special scheme to approximate convection. I wouldn't put significant stock in whether or not the NAM shows simulated reflectivity.

 

[Trey Thee]

Remember that the NAM is not a convection resolving model (unless you are looking at the NAM 4km). At 12km, it relies on a special scheme to approximate convection. I wouldn't put significant stock in whether or not the NAM shows simulated reflectivity.

That's a good point and one that I frequently forget myself. I still wonder though if this cap isn't going to be tough. Even SPC held things at 15% on their day 3 and when I went to bed at 9 last night, I fully expected to wakeup to 30%...

They seem to also question the storm coverage quite a bit at this point.

 

[Jared Orr]

Well, the 12z NAM is definitely pointing towards the Wichita area with a triple point storm, and it is not showing anything being able to break the cap further down the dryline.... I hope this changes, otherwise this may be an El Reno like situation where the models only depict one area of initiation that turns HP and every chaser out there is on that storm.

With Kelton's mention of the less-than-perfect moisture depth, a max of 1.5 PW progged by the NAM for central KS, and pretty stout winds above 500MB to vent the cells, I can't see HP becoming an issue. I think it's looking like a very classic mode kind of day.

That said, chaser convergence will undoubtedly be some of the worst we've seen in a long time...with the hype of this event and the slow start to the season.

 

[Stan Rose]

The models have been struggling with this system for days now (especially horrible--the EC, which is finally falling in line with the other progs) The NAM hasn't been much better, ive been using the GFS which has stayed fairly close to ensemble means. With the GFS, the upper jet is significantly (30+ kts) weaker, which as someone mentioned earlier could mean issues with storm organization, and it's also considerably farther east/north with the triple point. Still, with all that huge shear some long tracked sups seem a good bet...I'd certainly be out there if I wasn't stuck at work. But, it doesn't look as good as first impressions would suggest. The high res stuff will be interesting to see tomorrow.

 

[Dan Robinson]

The classic Plains aspect of this day has been covered well in this thread so far (a big thank-you to everyone who has chimed in), so I won't rehash it. I have learned in studying events like this that there are almost always multiple tornadic supercells in the Midwest if the upper support reaches that far east. I am becoming more confident that this event will likely produce, at least briefly, along the length of the warm front in MO/IL. Newer runs of the NAM and GFS have been pushing a secondary (southern) jet max increasingly eastward across the warm frontal zone in MO. The advantage in this area is that storm motions should be slightly slower and more east-northeast, giving storms a longer period of time over the boundary and a better chance of deviating. The main drawback in this area is that the cap is wide open very early in the day, and it is likely a large MCS will evolve quickly.