6/7/09 FCST: NE/IA/KS/OK

[Melanie Metz]

Yes, there were many tornadic supercells that day, with the stronger cells south of the warm front in the more unstable warm sector, just ahead of outflow boundary/ dryline intersection. Cells along the warm front were more elongated and didn't maintain as long but did produce some tornadoes. May 22nd was a very potent day with everything in place.

This last run did seem to slow the system down, but not too much to discourage me. I don't know how many times days look promising only to see the system slow more and more each run! I'm still liking the 7th though. We'll see what the morning runs bring!

 

[Scott Weberpal]

Too me this set up looks a bit familiar to the Hallam Nebraska Tornado Outbreak. Most of the warm sector in KAnsas also didnt have many reports of anything, as to what you are saying above.

The 00z NAM shows a very strong convective signal in SW IA before 00z (7 pm) Sunday evening.

http://www.tornadofx.com/stormtrack/Sunday00z.jpg

H85 temps around 18c, and H7 temps between 10-12c should be breakable.

 

[Mike Smith]

Mods: Suggest adding KS and northern OK to thread title.

I am going to be the odd man out here and opine that there will be enough dynamic forcing (if the 12Z NAM and 00Z European are correct) to break the cap in Kansas and, perhaps, N Cent. and NW OK. In addition to the PVA, take a look at the difluence centered over ICT at 200mb ( www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/nam/12/images/nam_200_060m.gif ). These are unseasonably strong winds from 500mb on up at this latitude. With SSE winds at 850mb ( www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/nam/12/images/nam_850_060m.gif ) this -- if the cap is able to break -- an excellent situation for this late in the season.

Winds along the Texas coast are now southeasterly and there is plenty of time for a Gulf return between now and Sunday afternoon.

While it might be evening before storms develop, I believe there is reason to watch Kansas and northern Oklahoma for Sunday.

 

[Jeff House]

Agree with Mike. 00Z 6 Jun models show great directional and speed shear. Expect moisture return to be adequate after 48 hours. Western trough will begin to move out into the Plains by Sunday afternoon and eve. I will be in Wichita on Sunday and chase from there. Believe dryline will go in Kansas and I will target DL warm front intersection. Finally, morning rain should sweeten the whole deal.

 

[Brian Stertz]

Certainly liking the triple pt. target out in the Hays KS-Hill City KS-Hastings NE area....or thereabouts. The 00z NAM shows some interesting tornadic supercell potential in the corridor from Hill City to Lincoln NE. EHI's at both 0-1km and 0-3km are downright nasty with values of 8+. The GFS is a little south & east with this but the general ideal is the same. The good part of this setup is that there is warm air and pooled moisture on the north side of the boundary. Take this and in excess of 45 kts. of deep layer shear, and there could be some bigtime tornadic supercells erupting over NC Kansas and tracking into SC/SE Nebraska. This looks like a solid chase op. I plan on heading west on I-70 Sunday to a target in the Hays-Plainville KS area. Hopefully this setup can hit FULL potential. Not too many events this spring have hit that magic level.... although the SE Wyoming/NE Panhandle event was pretty much the chase event of 2009 to date it seems. Maybe a trend in the more active direction???

 

[Kevin Crawmer]

I just looked over the 00z NAM, WRF, and GFS. Obviously with these MCSs going over the previous night, a lot will be determined with the details of the day. As of now, I like an area between Nebraska City, NE (kafk) and Creston, IA (kcsq) Points west and south of there appear to be too capped with convective temps in the 90s or even up over 100.

The NAM favors Nebraska City:

http://beta.wxcaster.com/cgi-bin/parse_skewt_trace.cgi?model=NAM&fcsthr=048&STATIONID=kafk

Where the GFS appears to favor Creston, IA:

http://beta.wxcaster.com/cgi-bin/parse_skewt_trace.cgi?model=GFS&fcsthr=048&STATIONID=kcsq

**both are time sensitive

There is a very narrow area of potential in my opinion, but a significant storm or two is definitely possible, especially if there are some decent boundaries set up and clearing happens so instability can get cranked up as advertised.

 

[Brendon Lindsey]

Well I just took a look at 0z NAM I am not really gonna wait around for the GFS... As of now... Seeing as I am biased to closer spots, I think from Oklahoma Border up to Wichita, If the CAP can break, I think there is enough UA support to support a Supercell... LCLs could be better, Moisture isnt the greatest but it is do-able. Precipatation simulation show maybe a Tail end charlie in SC KS... That would be cool haha. How about that 4500 CAPE today in NW Oklahoma none of the models forsaw that!!!!! Well Lets see what the GFS shows...

 

[Mikey Gribble]

Backing 850's and AOA 4000 CAPE is good enough to get me out of bed. We are on the road driving home from the cap bust today, but I think the highway 54 to Hutchinson area looks great for an discrete storm. Yeah the lcl's will be high again, but I've seen worse in the last couple weeks. I wouldn't be surprised to see a tornado report out of tomorrow if the NAM is correct, and that is a big if. I'll check it out in the morning. That sure took me by surprise. It lessened the depression of the cap bust today because I wasn't planning on chasing tomorrow.

 

[Joel Wright]

Like many I have my eyes set on southwest Iowa for tomorrow. Best instability looks to remain down in Missouri and Kansas, but the northern edge of it will bulge into southwest/south-central Iowa. CAPE values in this area are projected to reach around 2,000j/kg according to the new NAM. This seems reasonable as long as the morning convection clears out of the way.

There should be a pretty decent boundary lined up east west just north of this area as well. Moisture will likely pool to the south of this and any storm that stays discrete should have a pretty decent chance of producing. 0-3km SRH looks like it increases a bit as we move past 00z 6/8 as the 850mb winds pick up a bit. I'm hoping the models are underdoing the strength of these winds.

Looks like our target will probably be in the Red Oak/Corning Iowa area. If instability fails to evolve as well as the models show we'll probably drop south into northwest Missouri.

 

[Mike Smith]

My previous comments regarding tomorrow (earlier in the thread), based on the new 00Z NAM, still appear valid and I would not change them at this point.

That said, here some additional information based on 00Z (this evening's) NAM.

There is a very nice short wave moving across the KS-NE area that should be sufficient to break the CAP. In fact, at 7pm Sunday, there is no CIN from ICT to EMP ( http://twisterdata.com/index.php?pr...nglemap&sounding=n&output=image&archive=false ).

SPC Tools show mixing ratios and dew points continuing to rise in KS. If we could get the thunderstorms now in KS to continue to increase there is even a chance of a weak boundary in the region, increasing low level vorticity.

Finally, the NAM shows surface pressures dropping 4mb from 1pm to 7pm tomorrow along the KS-OK border. That should help keep winds from sfc to 850 mb south to SSE.

Bottom line: I think a good part of Kansas and north central and perhaps NW OK have a real shot at supercells, and perhaps tornadoes, tomorrow.

UPDATE: The ICT 7pm sounding looks very favorable with 55kt winds at 500mb (impressive this late in season). At the same time, the Colderwater, KS grid point has 85kt winds at 250mb with very nice difluence over southern KS.

 

[Andrew Pritchard]

For what it's worth:

http://www.emc.ncep.noaa.gov/mmb/mpy...0/refc_f24.gif

That thing nailed today's cap bust and the supercells in Nebraska.

Wouldn't be surprised to see a small moderate risk over NE Kansas tomorrow. With models actually breaking out a good amount of convection and the progg'd wind fields plus bonus outflow boundaries I could see a few intense supercells anywhere from Beatrice, NE to southeast Kansas. LCL's are going to be pretty high for tornado potential over the southern half of that area, but could still be some big hailers. LCL's should be lower near the warm front, and with very strong low level shear I'd say any supercell that can form will have decent tornado production potential.

I'd say Topeka, KS by late afternoon for a decent tornado threat. Be nice to make it back to back years for tornadoes on June 7th.

 

[Darren Addy]

At this point, I'd have to say that Concordia to Hiawatha, KS looks extremely promising. The NAM's model skew-t for Concordia with SRH (1 KM) at 263.4 and LCL heights of under 500 meters. Supercell parameter there is 96.9%. Significant Tornado Parameter is 5.5. Mid-level lapse rates of 7.2. Hodograph looks very good (better the closer you get to the NE border in NE KS).

This day looks like our first May-like moisture return. NAM is saying 70 but as always, that is probably optimistic. Upper 60s would be more than good enough for some excellent CAPE in the area and I like the fact that the low level winds are not anemic tomorrow.

 

[Chad Cowan]

Tornado chances are looking stellar for tomorrow in eastern KS if we can get initiation to the south of the warm front. The forecast hodograph shapes are just about classic; unfortunately the second lobe of this potent EML will be over the target area tomorrow afternoon featuring 700mb temps likely 1-2C degrees higher than the cap bust we had today. BUT we will have a couple things working for us tomorrow that today lacked. First of all, low-level moisture may be of much higher quality given the trajectories coming from the western Gulf instead of northeast Mexico. This richer moisture may not make it far enough north in time to have a huge positive consequence but the extended period of low-level moisture pooling we've had along the surface front should be sufficient to weaken the cap and provide high instability. Now all we need is some lift to fire this loaded gun, which brings me to:

Above, from left to right, there is the 5z IR image, the NAM 500mb vorticity map for 18z and the GFS 500mb vorticity map for 18z. What you can see is a small piece of subtropical energy that was sucked up into this swrly flow from off the coast of the Baja. This subtle upper-level disturbance is forecast to be slightly upstream of the target area near initiation time which will hopefully provide lift with the help of upper-level diffluence and more significantly the strong, negatively-tilted shortwave ejecting across the Central Plains. This little piece of energy may not have a big roll in initiating convection on the warm front or triple point, but if I were targeting further south along the dryline I would be keeping a very close eye on it.

 

[Brian Stertz]

Active day ahead

Target seems pretty clear cut..sfc low, boundary shear and sufficently high CAPES will mean a rocking time between I-70 and the KS/NE border across NE Kansas...extreme SE Nebraska and eventually NW/WC Missouri. RUC on 12hr. forecast has solid CI in the Manhattan/Topeka KS area. Guess it is time to join the masses on a fun backyard chase.

A more detailed forecast later this morning....

 

[Justin Turcotte]

Setup reminds me of May 8, 2003 but that day had more robust H50 flow and rapidly mixing dryline allowing storms to fly once initiated. Right now an OFB along I-70 is intersecting the front in central KS. At peak heating this point will be near Salina. Consensus target among forecasters on the night shift is Junction City, KS. Nebraska looks to be socked in clouds much of the day but the extreme southeast could see some clearing. I figure areas north of Concordia to Falls City will have a better shot at slightly elevated hailers while I-70 is the focus for a tornadic supercell or two. A few folks from my office will be chasing today. Given the setup is good enough for chasers from Grand Forks I can expect a chase circus in addition to what mother nature provides.