05/29/04 FCST: Central Plains

Mar 2, 2004
Northern Colorado
The NWS in Wichita had this in their HAZ WX Outlook this morning..


I haven't glanced at anything to support this, but if it pans out, it will likely be the last dance for this May-a-Thon I've been on. I usually have pretty good luck on Memorial Day Weekend.. lets just pray gas holds about steady and doesn't rocket in price before then.
Will take up a spot west of Hebron NE now. 500 winds pretty weak, but with the more backed low levels it should be ok. 700 and 850 temps rather high, but you gotta play anyway.

NWS OUN has been harking on the possibility of signficant severe wx outbreak in the plains for the past couple of days... Looking at the synoptic setup, there is pretty remarkable similarities between Saturday's setup and May 3rd, 1999. My only concern right now is available moisture, but hopefully we can get widespread 70 tds in ok/ks/s NE by then... Otherwise, looks like a "typical" dryline tornado day, as long as we can break the cap.
OK....Now I'm excited about Sat/Sun.

I'm sure the shtwv/UA disturbance timings will become more clear between now and Sat/Sun. but with a large trough coming out into into the plains in late may (you can't get a much more climatologically favorable timing) I can almost smell an outbreak in the works. Looking at placement of H5 features on the 18z ETA makes me think the major action will be north of the southern plains especially because the CAP will be an issue further south. With the dynamics currently depicted, however, a CAP could be easily overcome. We shall see.... :D

Oh also, thank god for 4 day weekends!!
Just wanted to draw everyones attention to a possible issue surrounding this weekends possible major event coinciding with Memorial Day holiday.

I was speaking with a veteran chaser on the phone this evening and he reminded me that the SPC outlooks, NWS discussions/forecasts etc. will be toned up this weekend given how large numbers of people will be out and about. In other words, even though the event looks like it could be really good now, the forecast wording for this weekend is likely to seem especially strong or ominous given that the forecasters want the public to be extra aware no matter the actual meteorological outcome.

I'm sure many of you have already thought of this. My whole point I guess is that it might be wise to take some of the professional forecasts from this point forward with a grain of salt.
Saturday does look promising! Actually, per the ETA 60 hr forecast that's the only day that shows potential for storms to be more discrete, supercellular in nature. Gotta LOVE that negative tilt!!! Looks at this point like the bulk of the instability will be over NE KS, which coincides well with the highest Td's, lowest LIs, high Theta-E temps (in the mid-80s, at least) & strong low-level jet dynamics. Helicities also look great over that area which, given the way the winds veer strongly with height, makes sense. I really like the way the winds back across the entire area. This also fits the picture, considering the strong pressure falls ahead of the low. Assuming (and hoping) the ETA forecast CAPEs for that day actually verify, Saturday's going to be a big day. I know I'll be out there!
Current target area: Salina
(This will almost certainly shift further east-northeast, but there's a FlyingJ at the exit just east of Salina; that's where I'll make my last data stop before starting the chase.
See everyone out there!
I'm hoping for an outbreak this weekend, however at the same time I'm hoping for a bust. I was supposed to be out in Oklahoma this week and next week, but due to uncontrolable circumstances I'm unable to be down there. :( I hope I dont miss the big one.
Going OT - sorry admins :oops:

But this setup just looks too potent that after returning back to England on Tuesday - and am turning right around and flying out of London tomorrow for just three days of chasing - now thats what I call commitment :wink:
Good for you Stu. I think you should move to Oklahoma/KS/or TX. Might make chase trips a little cheaper. Hope you see the wedge.
The setup definately looks nice for Saturday, not 100% sure yet on where I want to hang out at for the day but thinking somewhere between ICT and Salina. I'll know for sure Fri. night.

Hope to see some of you out there this weekend! I'll post a picture of my chase vehicle later this evening, so if you see me feel free to stop
If I had to pick a target right now, I would pic Wichita Kansas so I can have access to several major interstates to go NE/SE/or E. I would really like to head down there as it looks like eastern kansas is in trouble over the weekend with capes 0f 2000-4000 and helicities approaching 400 in some areas and dewpoints in the 70s. Its looking interesting.
When I was younger and didn't have a family to worry about, I would be really looking forward to Saturday here in Eastern Kansas. But I guess I'm getting old, as I'm actually worried rather than excited. We've had several near misses here in Lawrence lately.

I'm not exactly sure why the Day 3 probabilistic outlook only has 25%....and not even hatched. LOL. The text doesn't seem to match the rather heavy wording. It cracks me up how matter-of-fact Thompson's tone is in the discussion...it's like he is writing"Well, the model forecasts show 'Day After Tomorrow' conditions will develop in the southern and central plains. Mutliple wedges are likely, including a few wedges side by side..." while yawning. :lol:

Moving on...

What already appeared to be a very potent weather situation has become increasingly more ominous with the 18z ETA run. It stacks up like this:

Synoptic Setup:
Negatively tilted longwave trough
Surface low in SW to WC Kansas
Warm front extending NE into N. Kansas and SE Nebraska.
"Cold front" (not much of one) extending SW from the low into Colorado
Dryline extending south from surface low into W. Oklahoma and W. N. Texas

Dewpoints - Upper 60s-Low 70s (perhaps even mid-70s) over the S. and C. Plains.
SBCAPE - 2500-3500 j/kg over the S. and C. Plains (most likely much higher..being conservative here)

Wind Shear:
Surface - SSE-SE at 15-20 kts
850 mb - S at 40-55 kts (00z run had up to 45 kts)
700 mb - SW at 40 kts
500 mb - WSW at almost 40 kts (it will likely be better if we can get a decent s/w)
250 mb - WSW at 70-75 kts

Convective Inhibition:
CINH less than -50 j/kg along and east of the dryline and locally down to 0 j/kg.

Synoptically speaking, this is the type of weather situation that I would draw on my notebook paper when I got bored in class....in other words, the perfect system. Of course, this isn't that yet...but it has the potential to get very bad across the central United States on Saturday.

with all the talk of an outbreak, is this looking like an April 26 91/march 13 1990 outbreak? I'm not familiar with the synoptic conditions of those days.
Re: Whoa...

I'm not exactly sure why the Day 3 probabilistic outlook only has 25%....and not even hatched.

The Day 3 Outlook can only go to 25% unhatched... Day 2 can go to 45% hatched...

I agree with Gabe's take on the situation. I'd like 500mb winds to be a little stronger, but I've heard that the ETA has bias towards underforecasting shortwave strength / mid-level flow strength for forecasts >24-36 hrs in advance (the HPC Model Diagnostic Discussion mentioned this a couple of days ago I think). Strong mid-level flow would give us slightly stronger mid-level SR flow, which would help move potential storms away from the HP spectrum and into the classic part of the spectrum. However, such winds have proven sufficient at other times this year and will likely mean that we chasers could tripod the storms, in contrast to the "gotta keep moving" mentality that was necessary during the storms of "First Ten Days of May" (sounds like a movie, eh?) last year... I'm worried about the ETA mixing out the 70 Tds over OK, which is yeilding model-forecast CAPE of only 2500-3000 over OK -- obviously sufficient for tornadoes, but not typical of the synoptically-evident tornado outbreaks... 18z ETA does show 0-3km helicity values >400 east of I-35 in OK... I like OK because the better upper-level flow stays mainly in OK, and decreasing northward. Cap strength doesn't appear to be an issue, and will likely be less of an issue if we can keep 70 Tds in the OK part of the warm sector...
Day 3 (saturday) looks like the kind of setup you see only in ideal situations in the classroom or such. Right now, I'm heavily favoring Oklahoma because of the attendant risk of more discrete storms, but the cap won't be as strong as earlier was thought, so there may be more storms to deal with. If the 70s TDs don't mix out, we're looking at a huge day. I know I'm not saying anything new for everyone, but what else is there to say? One thing, I hope these things will stay out of populated areas, but when setups like this occur, its unavoidable. I hope the TV and Radio can keep everyone covered, especially since a lot will be on the lakes or traveling through.
with all the talk of an outbreak, is this looking like an April 26 91/march 13 1990 outbreak? I'm not familiar with the synoptic conditions of those days.

You can find the conditions for many significant outbreaks here - http://www.spc.noaa.gov/staff/hart/outbreaks/

Looks like this system will rapidly deepen between Saturday and Monday...With ETA showing the low bombing out in the Midwest...With probably a good tornado outbreak in the Plains, translating into a pretty intense derecho, possibly rivaling the May 31, 1998 event across the Midwest/Great Lakes, if the ETA holds true...

Well... looking at the latest 0z ETA (LOL), the threat of signficant outbreak continues. The ETA continues with a widespread area of very strong low-level shear (+400 m2/s2 0-3km SRH) mainly east of I-35 in eastern KS and ne OK. Mid-level flow forecast remains a little weak, but doable. The ETA continues to mix out the 70 degree Tds in OK and KS, more so than previous model runs. This could spell some pretty big trouble for chasers, given the forecast CAPE remains less than the typical (whatever typical means) synoptically-evident outbreaks, w/ CAPEs generally in the 3500-4000 range. Additionally, the mixing out of the 70 Tds leads to a pretty strong (very strong) cap over the area of best low-level shear by late afternoon -- eastern KS and ne OK. If the CINH of 100-180 verifies, we're not gonig to get the signficant outbreak that we otherwise could have. However, if we can keep those 70 Tds, it'll up the CAPEs and drop the CINH to breakable levels, which would allows cells that move/propagate off the dryline to move into the region of very (almost scary) low-level shear...

P.S. -- of course it' encouraging to read "AT THIS TIME, IT
Well, I'm flying to OKC tomorrow afternoon and I'm still very encouraged by the discussion on this thread, conversations with my chase partners and the 0z ETA run. Good Tds mixing out is a possible issue, but I like how the 48hr ETA forecast shows a moisture "bubble" or pooling in NE KS of some 70 dews. Of course this could be some sort of spatial/meteorological error attributable to grid scale feedback or something (hopefully not). Also the surface forecast map is downright awesome.


DPs(moisture pooling in NE KS?):

I will be anxious to read the new Day 2 tomorrow as well as all the new AFDs and HWOs from offices in the approximate target area in the mernin.
It looks like a large part of the plains will be vulnerable to tornadic supercells Saturday.

The eta prog for 18Z Saturday shows a large area of 68-70 dewpoints along and ahead of the dryline in KS/OK and surrounding states. The CAPE is progged to be on the order of 4000, and deep mixing ratios on the order of 14-16 g/kg support these numbers (note, this deep tropical moisture has made it ashore as of 00Z tonight at BRO, CRP and LCH). At the 00Z time step, convection has broken out in the eta model, and due to the way convection is parameterized, the dewpoints and especially the CAPE drop some in the model by 00Z Saturday night. This is known eta model behavior to eat the instability up too quickly when thunderstorms are initiated, so it is not a big concern to me right now.

Wind shear looks good to excellent over a large area. Rapid pressure falls should be ongoing, so the isallobaric forcing should allow the winds near the surface to back. With 40-50 kts from 1km-6km, and 65-70 kts at anvil level, shear will be more than sufficient for tornadic supercells over a large area.

The cap is strong, but not overly so. In fact, I would prefer a strong cap on a day like Saturday, to help the moisture pool along the immediate dryline boundary and to pump the instability up as far as possible before initiation.

I suspect the biggest problem for Saturday is not whether to play, but where. There will probably be a legitimate tornado threat over a rather large area, as was the case Monday.
Well, after learning to pronounce Bee-yah-triss in true Snoop Dogg style and finding our favorite lodging of all time in the region (can't say where lest Martin Lisius file it away in his Rolodex at the Tempest Command & Control Center), it would only be appropriate to return to the scene of my crime, the place I left my chasing heart and soul a few days ago. So I'm rooting for Hebron as a target (have not looked at models tonight). I will drive to the center of Thayer County and sit cross-legged, guru style, until I am lifted by a tornado and carried back to Indiana. I'll never leave my target again.

Tonight, I bought a cowboy hat at the Denton Cracker Barrel for good luck. It actually fits and looks silly enough that I hope the storm gods are satisfied with my hubris.

Okay, so I don't have to send a PM to myself about superfluous posts in Target Area, I'll say that when I looked at the 12Z ETA, I saw moisture pooling in southeast NE and a strong dry punch working into north central Kansas, perhaps a little more south than where it was on the 24th, as the low was further south as well. Still I could see the warm front making the border and storms just north of the baroclinicity winding up along the border or just south, if that makes any sense. Maybe I'm looking for a way to initiate in Nebraska. I feel silly since the rest of you are talking about Kansas. Perhaps the 12Z is already way obsolete? I'll have to look.

Anyway, lots of energy, nearly-bombing synoptic sfc low, warm front draped that-a-way, dryline moving this-a-way---what's not to love?
Day 2 just came out, Moderate risk for Saturday

0236 AM CDT FRI MAY 28 2004