2012-04-14 FCST: TX, OK, KS, NE, IA

[J Trueblood]

If I were chasing tomorrow, I'd probably head towards Lincoln, NE. Mainly because the central plains are going to be absolutely littered with chasers. I also trust the warm front right now more than the dryline. There's a nice bullseye of EHI in Eastern NE, with more than ample CAPE. (Around 2500 at 00z)

Also, due to the relatively smaller area of favorable conditions, the storms might stay more discrete in the northern target. Although I'm not sure if that's actually what decides storm coverage.

If I were heading south I'd start in Witchita, KS and hope there's some parking spots that aren't already taken by the mass of chasers that is sure to arrive.

Stay safe everyone!

 

[Andrew Stoller]

NWS ICT's wording in their afternoon AFD is good or bad depending on whether you're a chaser or a property owner in the area! They're having serious doubts now about the forecast. I think the biggest issue now is the fact that the 500 mb flow will be a bit further north and west of the main dryline area and surface features, and that is where disturbances in the flow are likely to kick off convection. There's still likely going to be at least isolated supercells in the southern high risk area, but in terms of "outbreak", as in many discrete tornadic supercells - I think that is becoming a bit less likely. I think that is a result of the positive tilt if the longwave trough; it's ejecting out quickly now instead of having time to dig in, deepen a surface low closer to the upper trough axis, and create the balance of upper air features directly above surface features/dryline area.

If I was chasing, I'd probably start at least considering the northern target area. Man, this is a tough forecast because if at least one or two isolated supercells do get going before the cold front overtakes everything later tomorrow night, they'll be monsters.

:edit: and just as I thought, the NAM is slowing things down and the dryline is further west than previously progged. That might be a good thing as the jet streak is a bit closer to the instability axis over the southern dryline. Surface low at 00z is near North Platte! That's where I'd target. In fact, now that things are back that far west, I might mosey on up that way tomarrow!!! North Platte to Grand Island along the warm front directly east of the surface low/triple point and points to the immediate southeast will be the sweet spot IMO. In fact, I bet everything ends up even further west than it looks now.

 

[Chip Redmond]

Warm front lifts north through central Nebraska tomorrow afternoon around 18z. Clearing skies will quickly destabilize as the sun bakes the environment. It won't take much to get storms initiating by 21z near North Platte, NE and moving northeast at very managable speeds. Might not even need them to hit the warm front as forecast soundings are absolutely ridiculous curving through the entire column. Storms should remain isolated before abundant forcing from the cold front takes over by 0-3z. A substaintial tornado threat with the wind profile suggestive of rotating supercells. LCLs are on the ground almost which will enhance tornado threat quickly and shear/thermo profiles are suggestive of strong tornadoes. Will target N. Platte tomorrow. Should be an interesting day except for chaser convergence issues.

Chip

 

[Patrick Martin]

I've been sold on the southern cntrl KS target until yesterday, and now heavily considering a warm front/triple point play in NE. Looking over the 0Z NAM, concerned about the lack of upper air features (a notable shortwave) coming into the srn target during daylight. I think the key to the northern target is going to be the degree of overnight convection and how quickly it, and clearing can occur in the wake of it. My car is packed, and ready to leave at 8am tomorrow (gotta wait for the wife to get home from work to tend to our daughter), but the question is where. I can reasonably be in either York, NE or Salina/Hutchinson KS by 4pm local time, but like Andrew was saying, don't think I will necessarily need to be that far east. Long story short, final call likely to be made just before I leave. Good luck to everyone out tomorrow!

 

[Andrew Stoller]

I totally agree Chip. I'm thinking points to the east of North Platte along I-80 will be the show tomorrow. Previous runs of the NAM had the dryline further east away from the jet streak, but the upper jet seems to be becoming more inline with surface features, and now the main surface low around North Platte is actually a bit northwest of the 500MB flow. That looks to be a better solution for the entire outlook area and I think this now will be a good outbreak of tornadoes. 00z NAM has come in with much better helicity values in the entire warm sector and instability is even stronger. Wouldn't be surprised to see some earlier action to the north of the surface low earlier on, ala Windsor Colorado in May 2008.

 

[Ryan McGinnis]

0Z NAM seems to have shifted the low to the left (to the left, everything you own in a box to the left). The Hebron sounding at 0Z is pretty amazing.

 

[Jacob Ferden]

Not going to get too long winded here, but am targeting somewhere in the I-35 corridor between Norman and Wichita. One look at a few forecast soundings should spell it out: this has the potential to be one of the most volatile days you will see for the southern plains. I don't know that I've ever seen so many beautiful forecast hodo's. The whole key is initiation. IF (and it's fairly significant if) storms can go in a widespread fashion, I think the ceiling of this event is a lot higher than some people realize. I can see at least a possibility of strong tornadoes anywhere between the Red River and points north of I-80 in Nebraska and Iowa. Looking forward to the challenge of chasing it, not looking forward to the possible death and destruction.

 

[Bill Hark]

I am still impressed with Saturday. Mainly looking at the 00ZNAM, I like the approaching trough with 60 kt SW winds overspreading most ofOklahoma and Kansas through the highest winds won’t occur until very early AM(80-100 kt for central and western KS/OK-TX panhandles) The cap will bedecreasing per the 700 mb temps. The 5 degree contour shifts eastward by 00Z.Moisture should be sufficient as 65 dewpoints are predicted to reach the KS-NEboarder by 00Z. I wish the surface winds would be more from the southeast inOklahoma. By 00Z, they are from the south except northern Kansas into Nebraskaeast of the low where they are predicted to be from the southeast. The 850’s are also predicted to be from thesouth to slightly southwesterly across OK and Kansas. The 00Z GFS (that justcame in as I am writing this) showsbetter surface winds through OK than the NAM but the 850’s are moresouthwesterly. I think the predicted CAPE “nose” extending into southernNebraska of 2500 is also decent notwithstanding the 3500 bullseye in central OKper 00Z NAM. Right now, my primary target would be Holdrege, Nebraska mainlydue to the predicted southeasterly surface winds. My secondary target would be just ahead ofthe dryline in OK, maybe Elk City.

Bill Hark

 

[Robert Balogh]

Like Bill, I wish there would be a little better combination of 850mb and surface winds than either the GFS or the NAM is showing as of the latest (00Z) run, but I think that's a relatively minor issue. I am concerned that with the weak cap that there may not be many cells that stay isolated for long. Targeting to be near the dry line punch that the NAM projects to be just south of the Ok/Ks border at 00Z. Interesting that while the NAM shows the dry line still west of I-35 at 00Z with two bulges, the GFS shows no westward lag of the dryline in central Kansas, with the result that there is one very broad bulge and the dry line extending as far east as a line from Wichita to about Junction City. I am limited to the southern target for tomorrow, after not being able to chase the stuff in my own back yard today, so planning on leaving Lawton around 10AM with an initial target being Lamont, OKlahoma, which is on a line with Ponca City but west of I-35. I am WAY too much of a novice to be able to forecast effects from the outflow boundaries left over from tonight's activity, and will be interested to try and follow experienced forecasters' thoughts on this tomorrow

 

[Christopher E. Kincaid]

Leaving Des Moines here in a few for the area around York, NE. The temptation will be to chase the early storms that form in the west central part of NE rather than wait for the "better" ones that form later and more east. I guess storm motions won't be too crazy. Anyway... good luck to everyone chasing the north and south targets today and be safe. If you see a black CR-V with IL plates wave lol.

 

[Michael Thompson]

I actually wrote this up for an Australian forum before reading Bill's message. I am planning another plains trip in 2013 and the best practice is to do the virtual targeting - just be aware that the discussion is geared to my Aussie mates

Saturday 14th April 2012 ( USA Time ) Target-= Holrege, Nebraska

Surface chart indicates a surface low and associated triple in SW Nebraska, a dryline stretches all the way from the Mexican border to that low. Storms will fire along that 2000km corridor.

The impact of the low has been strengthened somewhat by SPC, the shear is quite staggering by Australian standards, approaching 100kmots at 500mb, and even 70 odd knots at 700mb.

Due to the better surface to 700 winds moisture may not be the issue I thought it was earlier.

I am going to risk it and go playing the triple point and strong shear in Nebraska.

Storms could produce some long tracked but very fast moving tornadoes.

If you want surer options Oklahoma and Kansas appear safe bets, but may become ugly late in day as storms come into a squall line or convective complex.

Why Holrege - I always look for towns with good road options, any roads that go SW/NE along the flow of storms are especially desirable in the mid west and this town fits the bill.

 

[Jared Orr]

Wow. There is some serious model disagreement on precip and placing of the features. From left to right, we have RUC, NAM, GFS. Hopefully these issues are resolved in the next few hours. This may be due to the atmospheric effects of last night's/this morning's storms. What do you think?

Due to the uncertainty associated with the instability, initiation, and mode of the Neb target, my group will probably set out from Kansas City on I70 towards Salina before deciding whether we're going to swing north or south. It'll give us 2.5 more hours of decision time to watch how things resolve.

 

[Trey Thee]

New SPC guidance is out and they upped the wording and increased the size of the high risk area. "Strong-Violent and Long-Track Tornado Episodes".

Looking over the model data this morning there is some disagreement as Jared mentioned, but I believe that is due to this mornings storms as he mentioned. I do think these storms will leave numerous outflow boundaries in their wake which would potentially enhance risks later on today should a supercell move into one of them. At this point we'll target somewhere west of I35 between Norman and the KS border. We'll probably work that out a bit later.

I expect initiation for at least a couple of supercells by 4 or 5 pm. I don't see anything at this point ot preclude development. I am also thinking many are underestimating the impact of the upper low on the southern area. As we near 7pm to 9pm we may have cells firing ahead of the dryline if this goes down like I've seen in the past. This is potentially a huge event, people need to stay safe pay attention.

Remember both Lincoln and Norman have their spring games today...traffic is going to be TERRIBLE in those two areas. Don't get stuck in a life threatening situation.

 

[Kelly Sugden]

Westward trend in the models (12Z NAM) with the dl. DDC/GLD cwfas could see some storms. Bunkers right moving vector is 40-45 kt. Ick.

 

[RCarstens]

Can't overstate this quote enough. I live in Lincoln and will not be going anywhere today. 65,000 people will be here for the spring game and ALL roads, especially between OMA/LNK will be jam packed early this afternoon. I know everyone wants to see big storms today but avoid SE nebraska if you can between 2-5 because of congestion...pray that nothing happens around Lincoln and Norman during these times because at least here not enough people will be paying attention.