3/8/06 FCST: South-Central Plains/MO Valley

[Mark Oerther]

OOOOPS!

Yeah, the new probability scale has got me thrown off. After reviewing the new scale the 30% seems very reasonable. And I agree that storms will develop in southern area after dark. Racy, thanks for the reminder on the Zulu times and evening precip. I should have mentioned after dark precip was going to occur.

 

[Mikey Gribble]

Well I'm not to impressed with the tornado potential for tomorrow. Unlike today, I do think we will get storms to fire at a reasonable time. I haven't looked at much yet, but I really don't like veering 850mb winds. I am a big fan of directional shear and it just isn't there tomorrow. In addition to weakening our tornado potential, the lack of directional shear is also contributing to faster storm motions (NE at 35kts). It is doable, but there won't be a whole lot of time to get out and take pictures. It is definitely a chase day for me since it is close to home, but I'm not getting my hopes up. It looks like we could have some splitting supercells tomorrow. If we get a good right mover with better SR shear we might be in business. Good luck to everyone out chasing tomorrow.

 

[bbarjenbruch]

If you get a chance, check out the 00Z NAM forecast sounding for KTOP. This is roughly my target for tomorrow, probably a bit farther south and west along the front in all reality. At this time, the warm frontal boundary has shifted slightly south of TOP giving the East wind at the surface underneath SSW winds at 25 kts at 1000 m. This IS good directional shear.

As I eluded to earlier, I really don't see this as being an isolated supercell chase in any way. The key will be hitting any storm that forms along the warm front and following it until it drops something. It won't be the environmental winds in the warm sector that set this event up, but the great 0-1 shear at a very pronounced boundary. Also of note, the progged storm motion is ENE at 25 kts. I'm a big fan of this storm motion as it could have a great residence time in the frontal zone.

Perhaps I'm just looking for some reassurance and a reason to drive 3 or 4 hours to find a decent early year chase with a high bust probability. What does everyone think... false optimism or legitimate hope?

 

[Chad Ringley]

Fyi...4.5 km WRF-NMM run for the SPC has its precip/radar graphics out from the 00 UTC cycle...

http://wwwt.emc.ncep.noaa.gov/mmb/mmbpll/cent4km/v2/

Front activates around 00 UTC from Enid northward to Topeka. Discrete convection appears to develop along dryline between 00-03 UTC 09 MAR in N TX, then a bunch of convective clusters develop and progress across SE OK and NE TX into the overnight.

For what it's worth, the 4.5 km WRF-NMM did handle the warm front precip and convection in SC KS and NW OK on 3-7 very well, even though it was a few hours early on initiation.

I've already sold my soul to this model as you can tell haha

Enjoy, and good luck again to those chasing!

 

[Jeff Snyder]

Well, a difficult forecast for me tomorrow... CAPE should again be in the moderate range for March in the southern / central plains, though again high LCLs / high Td deficits are a little discouraging. The NAM brings this trough out tomorrow so positively tilted that we don't have a very juxtaposition of strong low-evel shear and good CAPE across much of the warm sector (it does go neg tilt Thursday, though). As Chad noted above, the WRF-NMM run (which did quite well today with initiation, though a tad late, near Enid) does intiate isolated convection between DFW and the OK/TX border late tomorrow afternoon, with a quasi-linear convection from Lamont, OK, northeastward. The NAM is forecasting a relative weakness in the 850mb across nc OK, with stronger flow in sc OK, above more nicely-backed surface flow. This creates stronger low-level shear to the S and SW of OKC, with rather meager low-level shear north.

I'll try to post a more in-depth forecast discussion tomorrow morning. I REALLY want to chase tomorrow, so I hope things start to look up. For what it's worth, it seems that the Tulsa NWSFO favors nc OK for svr probabilities tomorrow, and actually has some strong wording in their AFD pm update:

Originally posted by Tulsa NWSFO

LATEST ETA
INPUT TO TSA GFE CONVECTIVE PARAMETERS
YIELD A MORE POTENT SCENARIO WEDNESDAY
WEDNESDAY NIGHT THAN 18Z DATA REVEALED.
LATE WEDNESDAY AFTERNOON/NIGHT CERTAIN
TO BE ACTIVE. BE READY. GW

--> http://kamala.cod.edu/offs/KTSA/0603080323.fxus64.html

Oh, in case TSA is wondering... I'm ready!

 

[brody_clifton]

Judging from tonight's 00Z NAM for tomorrow, I agree with the post above that Topeka appears to be about a perfect target. Just due east of developing surface low and along/very close to the warm front. NAM also indiicates strong moisture pooling with low 60s surface dewpoints in far eastern KS. 850mb Tds 10C+ in a narrow east-west band in far ne KS at 18Z, possibly indicating pre warm frontal convection moving out to the ne. 18Z output shows low 850 Tds for most of the region but building up to over 12C in parts of SE KS and 8-10C east central KS by 00Z. So a rather shallow boundary layer at noon quickly thickens by early evening. Judging from 700mb Ts, the CAP looks breakable around the Topeka area, with the 6C+ temps remaining south of the Red River. And in the left exit region of the 500mb streak moving crossing eastern OK into Western AR.
I also agree that if a storm or two could hug that warm front for a bit tomorrow afternoon they would have a much better tornado threat as opposed to places to the south, which are forecasted to all be in SSW surface winds. From what I see the only mitigating factor for the Topeka area bullseye of parameters could be thick cloud cover aloft, but will just have to wait and see. Best daytime target at least I see, unless that surface flow is progged to back more in the next runs.
Right now the GFS is faster with the system, moving everything 250 miles or so the ene by mid afternoon, but with roughtly the same target relative to the surface low and warm front/triple point. My guess is the NAM is more on with the location of this one, keeping the action in east KS.

 

[Jason A.C. Brock]

DECISIONS DECISIONS

Looks like you are in the same pickle I am Jeff. You are much closer to the potential Kansas action than I am but the potential in North Central Texas is TEMPTING. I am only worried storms wont fire until about 6pm and this will be mostly a nocturnal event. Sitting in Enid this afternoon was bitter sweet. While the target area was good. The timing wasnt good.
Unless things just take a turn and look outright amazing in the morning for Kansas or NE Oklahoma I think I will take a chance on the Texas scenario. One thing about it....no blasting north suddenly if it looks like a poor choice about 5pm lol.
The cap will be stronger and the dynamics perhaps better in Texas but Kansas should be a pretty good "sure thing" as far as relieving SDS.
If things fire in North Central Texas about 3pm however things could go gangbusters and ill be one happy camper . Ill be glad when we dont see total darkness till about 9pm. Montague county usually gets in on the action on days such as these. Perhaps Cooke county and the Gainesville area towards Lake Texhoma.
I suppose for those who like ligthning photography chasing out of DFW this could be a great upcoming evening for you!

 

[Anthony Silver]

I'm looking at two targets for this afternoon: 1) I-70 corridor between Topeka and KC, and 2) Highway 54 between Yates Center and Ft. Scott, KS. I think #2 will be the best bet simply because the instability and wind shear look very favorable for supercells in that area. The only factor that may put a damper on tomorrow's activity would be the debris left over from ongoing convection. If the clouds linger around for most of the day, all bets will probably be off. However, if sufficent clearing and heating can occur, I would expect explosive thunderstorm development by 4 or 5 PM. In either case, I'll be out tomorrow afternoon. I'll look over everything around 9 or 10 AM and make my final decision on a target.

 

[Evan Stubbart]

Chasing

Based on the latest data I'm going to make Gainesville my camp until things start actually doing something here in North Texas. If anyone else is in the area- my cell is 940-783-2136. I think this might be a long shot though based on models.

 

[Jeff Snyder]

Man, the NAM has been bad with the sfc low position forecast... 24 hours ago, it had the low in west-central OK this afternoon; the new 12z has it way up near Kansas City. :roll: Regardless, models agree on surface pressures falling and cyclogenesis commencing farther south, from cenral OK into Texas, ahead of the strong vort max that'll head out of NM this afternoon and evening. Strong deeplayer shear, and upper-50s to low-60s dewpoints, should support supercells as the initial mode. Both the 12z RUC and the new 12z NAM show initiation in southcentral OK before 0z, though the NAM also shows precip is SE OK (though this looks a little dubious). As pressures all in this area, both the RUC and NAM indicate a kink in the dryline developing over sc/sw OK as moisture in north TX heads northward. With 1500+ SBCAPE, instability looks ok... As long as Tds are >60s, T-Td should be in <=20F, yielding LCLs that are at least 'doable'. North of I40, winds veer out as the sfc low in KS moves northeastward, so low-level shear is relatively poor (not that it's much better in sc OK). Clouds corrently cover the area se of I44, but they should move away within the next couple of hours. Occassionaly cirrus will traverse the area, but they should be thinner and less persistent than yesterday. All that said, I'm favoring sc OK.

EDIT: Doh! Again, no time for more indepth analysis (which is needed, since I mainly mention the models in the paragraph above -- need to compare w/ obs!). Apologies.

 

[C Brian Batey]

Re: Chasing

Originally posted by Evan Stubbart
Based on the latest data I'm going to make Gainesville my camp until things start actually doing something here in North Texas. If anyone else is in the area- my cell is 940-783-2136. I think this might be a long shot though based on models.

I think I'm going to stay north, but probably head a bit further west than that. Probably somewhere between Gainesvill and Vernon.

I plan to 'ride the dryline' during the afternoon and watch for initiation.

I've got a Stephen King book on CD. Wedgefest or bust, it'll be good to be out of the office!

 

[Bill Tabor]

Hmm Ruc's breaking convective precip out in Tx by noon. Hope that doesn't happen cause not that far away and I can't go!

 

[Bill Tabor]

I'm still looking at this but couple of big changes I notice per NAM:

1) By 18z it shows sfc low today further in central or northeast KS whereas yesterday position (12z run I believe) was near Medicine Lodge.

2) Intense wave of vorticity was going to hit overnight tonight sometime after dark across Tx, but now appears to not be arriving until Thursday morning.

IMO this takes the sfc system further east and begins removing it from the southern plains KS, OK, TX equation quicker and with late arrival of vort really should minimize what we see tonight.

I'll have to keep examining this. I'm doing this while watching stocks - so distracting.

Edit: The wave has slowed, but influence will arrive Thursday morning by 12z perhaps earlier so nighttime activity can possibly be intense as previously expected.

 

[Mike Hollingshead]

Looks like ne KS could go fairly early today. 15z RUC has stuff trying to go there by 3. It then has a broken line of convection trailing sw by 6, including right where I'm at now in Winfield KS. So, expect this area to go crazy as I leave here and head north. I guess I'm heading towards TOP area right now. SPC meso page has 1500 sbcape there and the cin is showing down to 50 is all already. So, anyway, something near the sfc low could go pretty early today.

I see spc will be upgrading for the wooded areas for tonight. Good luck to all heading out today.

 

[Dan Dawson]

1500Z RUC is looking more interesting to me for SW-SC OK. Between 21Z and 00Z it breaks out precip along the dryline from SC OK southward into N Texas. This appears to occur while, as Jeff noted above, a kink in the dryline forms in response to a developing surface low in the OK panhandle ahead of the approaching trough, as the lead low moves off into NW MO. The surface winds locally back on the RUC in this area too, and this also happens to be the area with the highest CAPE. It will be interesting to watch this unfold.