10/17/07 FCST: TX / OK / KS

[Brandon Lawson]

Wow I had not even looked at this. My friend Curtis McDonald made me aware of the 54 hour WRF SLP/6hr Pcp graphic. This has long track supercells written all over it. And one of them tracks right through Norman. Then the others track through Joplin, MO, Kansas City MO, and Chicago Il. Obviously this could change. But talk about a model picking a convective mode. This is crazy.

 

[Jeff Piotrowski]

Significant tornado's on Wednesday in Oklahoma & Kansas.

The 0Z WRF looks great for long live tornadoic storms across Southern KS, Oklahoma, on Wednesday ahead of dryline. I would expect a couple of very damaging tornados late in the afternoon into the evening hours. The prime target at this time the left front quadrant of the 500 MLB jet 70+ & the 850 of 50+ cross over is along and east of the I-35 corridor. The area with the best shear, cape, LCL, LFC, and EHI, is NE OKLA & SE KS.

 

[Jonathan Behle]

Lets keep in mind how these systems tend to lag west a few counties (or more) about this far in advance from what all the computer models say...We'll have to see how much this digs as it enters the picture across the Western States and see what time it does get to New Mexico then ejects Northeastward...

With that said and not throwing in the slight west jog that always seems to happen, I would set shop roughly from Ponca City OK to Hillsboro KS..

 

[Derek Weston]

I agree with Jeff. E/NE Oklahoma would be my spot. In my arm-chair chasing this season, I haven't seen many models spit out that combo of helicity and shear in the same area often. My worry is going to be the cape, dunno how juicy it's going to be getting up near the Kansas border... might be stretching things a bit. I'd like the track to jog south just a bit here, but... not too much to complain about. (I think this is going to be an Oklahoma show)

Interesting that the SPC went mod-risk. Guess that's a vote of confidence for this setup considering most of the recently promising setups put forth by the models pooped on us as the big day neared.

 

[Paul Knightley]

The latest ECMWF pushes things through rather quickly, as does GFS. However, given the *fairly* classix synoptic set-up, I would think dryline supercells are quite likely in N TX/OK/S KS, along with a chance of lower-topped supercell activity closer to the low across central/N KS. The ECMWF actually looks to generate long-lived thunderstorms, or thunderstom clusters from W OK, through cent N OK, and thence E KS.

 

[Andrea Griffa]

Very strong setup tomorrow. Taking apart the very high dews, with a 70 forecasted in Norman,Ok,by WRF, I like so much the intersection between the outrageus mid level vector and the dry line that could be useful to have not a linear mode. Quite dangerous situation maybe for the metro area of Oklahoma city that could be in the middle of the best parameters for tomorrow.
Good luck to all the people that will be chasing.

 

[Jeff Snyder]

I'm concerned about the timing of the vort max/trough... This morning's 12z NAM indicates that the leading edge of the vort max and associated DPVA will be near I35 by 18z, pushing into western AR and MO by 00z. What that may mean is convection developing near the dryline in the late morning, which may hose crucial afternoon insolation. There is going to be a very significant amount of moisture and warm air advection overnight through tomorrow, which tells me stratus and elevation convection may be a significant issue (as we know). >70F Tds may get to I40 by tomorrow afternoon, which would likely enhance tornado potential across SE OK and W AR. If this trough can slow down ~6 hrs, I'll be very happy.

Forecast soundings still look to support relatively low-topped supercells, with short but fat CAPE profiles (which, I suppose, still yields pretty good CAPE density) and an equilibrium level near 350mb. I still think that somewhere in the warm sector is likely to get good insolation to boost CAPE >1500 j/kg by afternoon, but we'll see. This is a very conditional event, but I think the probability of strong and maybe violent tornadoes is significant, particularly where Tds can reach 70F or beyond. Anytime there's 250-350 m2/s2 0-1km SRH in the warm sector of a negatively-tilted trough with >65F Tds, there should be red flags raised. This doesn't look too much unlike a more typical winter Gulf coast setup, with intense low-level shear, very impressive low-level moisture (and low LCLs), but relatively marginal to moderate instability. The SE KS,NE OK, and SW MO region may be the most reasonable for many chasers in the area, given storm motion and chase terrain concerns. I do think the greatest high-end tornado threat may be located farther south into southeastern OK, far NE TX, and SW AR tomorrow evening. IF this setup doesn't work out, it's nice to see yet another risk come Sunday (another thread).

 

[Mikey Gribble]

What a difference a day makes. The last model run I saw was the 12Z NAM from yesterday, which wasn't impressive. Today's 12Z run still has its problems, but the environment is quite favorable for strong tornadoes assuming we get adequate insolation over the warm sector during the day.
I am on board with Jeff. The major problem is going to be the amount of clearing and insolation we get over the warm sector tomorrow. At 18Z it looks like a god damn bomb went off with convection all over the place. I hope that's not the case. I like the OKC area for my initial target. I wouldn't dare chase in SE Oklahoma. I really like the extremely strong low level winds (850mb around 50kts) and the better deep layer shear extending farther North than yesterday mornings run, which brings southern Kansas into play. The forecast sounding for Tulsa has an amazing hodograph. Tulsa also has 1km SRH around 500m2s2. Combine this with 1km SR winds of 35kts (and everything else) and I think you have an environment that is very favorable for strong long-track tornadoes (if the NAM verifies). A secondary problem is storm motions. You can keep up with 40mph storm motions when you have good road networks, but it ain't easy. I updated my blog with a brief forecast http://loadedgunchasing.com/blog.html

 

[Buddy W Bradley]

I have looked at models, forecasts and threads most of the morning. If things hold like they are right now, I am going to leave work around noon and get into the Tulsa Ok area between 3 and 4pm. I feel the storms will initiate along the I-35 corridor as well, but rapid movement and storm motions to the NE will take the action into the I-44 corridor between 5 and 7pm. Also, as the low-level nocturnal jet kicks in, I expect the severe threat to continue into the overnight hours from S. Iowa across Missouri and Arkansas. Very damaging winds as well as a few tornadoes will remain possible during this time frame. All in all.... looks to be a very interesting, exciting "HUMP" day for a lot of us!

"If you can't be good..... be good at it"

 

[Dick McGowan]

Tough decision for myself tomorrow. I can't decide which area to chase! North of the low, low-topped supercells are likely, and with it I'm sure a few tornadoes. I don't think I can make the southern Oklahoma target in time, as I won't be able to leave until 10 a.m., and I'm unsure if I can make it to the low-toppers either (18-19z initiation?).

http://wxcaster2.com/CENTRAL_ETA212_SFC_SLPSBLI_33HR.gif
http://wxcaster2.com/CENTRAL_ETA212_SVR_CAPESRHSWEAT_33HR.gif

Pretty good lift at 21z in Central KS, and looking at Bunker's storm motion for that area, 40-45 knots in Central KS for storm motion can be done, with a full tank and non stop driving lol.

http://wxcaster2.com/CENTRAL_ETA212_1000-500_SLPPRPTHK_33HR.gif

That doesn't look good for the OKC metro around traffic time. GFS is showing higher td's further north, while the WRF not as much around NC KS. I'm going to guess I end up in SC KS around Harper County, maybe moving a county or two east of the boundary to let storms evolve. Tonight's runs will tell all...hopefully.

 

[Dal Archer]

I do have some of the same concerns as Jeff. We really need to have the system slow down slightly to allow significant destabilization to occur. Early convection will likely lead to another late season bust.

However, with that short shot of pessimism out of the way, I am still quite excited about this setup. Assuming early convection doesn't screw us up, with the forecasted shear and other parameters in place, we could have quite a show (particularly for this late in the season).

My hope is that forward storm motions do not get out of hand however. It will be extremely difficult to chase if forward storm motions go nuts. With the 500 MB winds rocketing along, this could make for a very difficult (and possibly) dangerous chase scenario if the these things move too fast.

 

[Brian Stertz]

I've looked everything over real close...and my eyes are still drawn to two places tomorrow. C/SC Kansas for one and SC Oklahoma as the other. I have selected the C/SC Kansas target as the one I'll be going after with Rich and Ryan Thies. I think the LL shear is good and that the low-topped supercells will be efficient tornado producers. If I had more time to get south tomorrow and then the long drive back...that area between Pauls Valley and Tulsa looks pretty primed for more significant tornadoes by late tomorrow afternoon. I will take my bets on a few low-topped tornadic supercells on the dryline up closer to the deep surface low. This would be an easy catch either going down towards Wichita or west towards Salina, and points a bit west from there. Like the nicer and friendlier storm motions too across C/SC Kansas (25-30mph KS vs. 40-50 OK) The hodographs seem very well looped to sustain tornadoes across C/SC Kansas too. Best of luck for those heading out tomorrow. Maybe see a few of you out there.

 

[Ben Prusia]

Analyzing the 12Z model data runs from the GFS/NAM, there is still some model difference regarding the potential instability that is forecast throughout the 2 state target areas of Kansas and Oklahoma. GFS is painting a more severe situation across Kansas while the NAM is painting a more severe situation across Oklahoma; the NAM is showing lower Tds in Kansas than that of the GFS model. But at least both models can agree on something, there should be a risk of significant severe weather somewhere along the US-81/I-35 corridor. Both models show a strong SW-erly and W-erly 500mb jet streak along with a strong and more southerly 850mb jet streak intersecting each other in Kansas and Oklahoma, which only adds up to a very decent amount of shear available for storm development. A concern about tomorrow is the forecasted cloudy skies and ongoing early-mid morning convection that could put a hamper on mid-late afternoon events, another being the more rapid storm motions that can be found in Oklahoma compared to any storm that can fire in Kansas. The way I am looking at right now, I will be setting up shop somewhere between Ponca City, Oklahoma and Newton, Kansas; I will most likely start out in Wichita and analyze data there before any further movements. One item of note was a forecasted base reflectivity map from the NAM for 0Z Thursday shows a lone cell in central Kansas, something that is to be kept in mind. Nothing can be said about having a good shot of severe weather on a day I am off of work in the middle of October!

 

[Jim Bishop]

I have two concerns:

1) Amount of convection/cloud cover that occurs in the morning across Oklahoma/Kansas, and the extent to which that clears out in the afternoon. There should be enough space between that 'mess' and the dryline to the west to allow enough destabalization, but it's always a conditional situation, something that's a worry until the late morning the day of the event.

2) Veering 850mb winds late in the afternoon/evening. The GFS veers the 850mb winds from the south-southwest at 18Z to the southwest by 00Z. This advects dry air into part of the warm sector, which could cause major problems with the storms that fire. The main concern here is storms will weaken or even die, or at the very least have a lower tornado probability. However, storms will be moving rapidly northeast around 40-45 mph initially, so they may be able to remain far enough in the warm sector to where only some dry air entrains into them, causing more LP like supercells. Either way, I do not like the veered 850mb winds.

These two concerns are a double edged sword, because while the dry air entrainment will quickly clear out the morning cloud/rain debris, it will also cause problems with the new storms that fire.

Forcing and shear will be incredible nevertheless, so as long as these two factors don't screw things up, there should be a few big tornadoes tomorrow in Kansas and Oklahoma.

 

[Dustin Wilcox]

Per the 18Z run there are two decent targets for tomorrow IMO, first one being NC KS where a sub 990mb low aids in strong backed sfc winds and a SSE 40kt LLJ, while instability is not progged to be quite as strong across this target as opposed to the southern one, the model still indicates 0-3km Capes >200j/kg, the strength of the low and subsequent DL bulge make it an appealing target area, however the area is on the backside of the upper level wave and unlike the southern target lacks the strong upper level support. The more southern target area looks more interesting at this point IMO, the model indicates a second low pressure center will aid in the development of bulge in the DL across C OK, unlike the more Northern target this area appears to lack real decent LL backing with weaker sfc winds and a veering LLJ, that being said the area should see > instability, and will certainly see strong upper level support that should make for some pretty crazy speed shear values. I just hope we don't pick the wrong target area tomorrow.