3-28-07 FCST: SD / NE / KS / OK / TX

[Brandon Sullivan]

This mornings materials bring me to enough confidence to finally make a thread about this event. And while it is a ways out, it could be a significant, (and as you can see by all the included states) a widespread one too!! Basically for the outline of states I used the SPC 4-8 day, as it matched up nicely with the risk area I had drawn early this morning.. I wrote this post somewhere around 330.. But wanted to see the outlook before I made a fool of myself!

Discussion, 0z European models show an embedded shortwave trough in the southern stream long wave trough to move into the plains/Mississippi Valley Region at the start of the period.. And the other model analyzed, the GFS is somewhat slower with eastward progression of the main shortwave trough.. Although I wish the timing of the GFS would verify, the European timing and progression would mean more of a significant and widespread event, Although shear and instability parameterss are indicative of a severe event regardless.. A quick look at the ECMWF and NGM, shows the low to eject nearly due north, putting the entire area in the warm sector, with very nice return flow.. SKEW-T showing some pretty good instability/shear across the area... Timing may play key, but with such a dynamically driven system, it will most likely be able to hold together overnight... The system will likely continue into 3/29 posing a threat to the eastern outlook area.. I will be out of town on the 28th, I will be soo mad if the first high risk happens that day!!!! GRR!

This system has good potential, im ready for the new 12z models!!

 

[beaudodson]

I believe we have already had at least one high risk day this year.

The models are picking up on this system nicely. Depending on which model you prefer...it appears a decent shot at a squall line into the Missouri Valley - possible as far east as Indiana and Kentucky. Still a ways off...and multiple more risk days in front of it. This has been a prolonged event. I believe we are in our fourth day of a risk now? Tomorrow looks to be moderate as well. The Paducah, NWS is starting to mention the potential for severe later in the week...around Thursday or so. So looks like this is the one to watch for those of us outside of the Plains.

 

[Scott Weberpal]

Certainly looks like a widespread sig wind event. I don't like the chances of tornadoes given the relatively unidirectional flow...Reminds me a lot of 4/6/01. Strong confidence in sig straight line winds, much lower confidence in tornado outbreak attm.

 

[Doug Mitchell]

'Nuff said

 

[Brandon Sullivan]

Yes, we have had a high risk.. I should have been more clear.. I meant first high here in IL.. lol.. my bad... still on track with this system.. but im busy with planning tommorow at this time

 

[Brett Adair]

I wouldn't go anywhere near saying anything about a high risk just yet.....there seem to be a few things missing for a high. It doesn't look like a MAJOR Tornado outbreak like the first high risk of the year, so I don't see a high risk unless the tornado potential jumps WAY up. Does look like a widespread event. I like the 60+ dewpoint that the model shows....but 65 would be even better. I can see evidence of the pseudo-wedge across the Appalachian mountains with the 55° pool of points across East AL.

 

[Brandon Sullivan]

I know. I was simply correcting myself from an earlier post.. Don't look for a high risk either.. GFS shows a strong unidirectional windfield.. looks favorable for damaging winds

 

[Andrew Pritchard]

Not being able to leave Macomb before 1:00 p.m., I'm thinking Cedar Rapids, IA would be a good chase target for tomorrow. One must remember that crossing the Mississippi River can be a challenge in NE Iowa.

Think you got the wrong thread there buddy

Thursday looks a lot better in the mid miss valley area on the latest gfs run. Surface winds are actually backed strongly, instead of this stupid SW crap it's been showing. That could mean more of a chance at sups, and maybe less towards winds ehhh, I don't know. It never really struck me as interesting until tonite's run as far as the gfs is concerned. Too early to tell though now, I'm sure the system will end up in Wyoming before all is said and done.

 

[Brandon Sullivan]

I am really starting to get excited on this system... Local WFO's really talking this up.. DMX even said it would be more significant than today.. Im liking it.. GFS is weaker, as usual, and faster than the ECMWF.. Im not sure if I would say weaker, as it shows a nice low. But it shows lesser on the dynamics and instability.. By tuesday, i will start planning more... Im more confident about this system than todays, in terms of severe weather

 

[Mikey Gribble]

I think this system is more than likely going to be the first major severe weather outbreak for the plains this year. I am still pretty skeptical on the tornado potential, but I am sure things will change a lot between now and then. Deep layer shear is good, moisture should be fine (although it's always a concern this time of year), and insolation shouldn't be an issue (over Kansas at least). I didn't look at previous runs very closely, but last night's run of the gfs had the moisture gradient spread pretty wide along the dryline. I don't think I'm buying that though, especially with surface winds backing. Another problem is that the shear vector isn't normal to the boundary. I don't think this is neccessarily going to cause a problem along the dryline, but it obviously causes some comcerns about storms not remaining discrete. I think by far the biggest problem is the lack of directional shear, which would put a serious dent in the tornado potential. As of right now, I would either target the dryline in north central Kansas or I would go down to southern Oklahoma where you get better directional shear. I think both could produce on tornadoes.
On another note, I thought Edwards did a fabulous job with the day 3. He is definitely one of my favorite forecasters.

 

[Brandon Sullivan]

I agree. Roger is a good guy..

Anyways.. This mornings GFS forecast thermodynamic profiles are looking good... They show a good target around the LSX area.. Im a little worried that the slowing of the system could cause some problems.. GFSX GFS are slwing the system way down.. Which wouldnt pose a problem to those of you in the plains states. but for us here in IL....... The QPF fields show the heaviest activity to the west of us.. over NE KS IA TX.. May be a good chase day. Sometimes it looks like instabilty may be outrunning the precip.. ? 12z materials out shortly.. Im busy with NWP ensemble training so I may not post until tonight.

 

[Brian Stertz]

Wed. setup

Just a quick glance at the 12z ETA data...it looks like the 0-3km shear and instability would favor the best chaseable tornadic supercell threat from NC Kansas into SC/C/SE Nebraska on Wed. I am not liking the looks of the qpf panel, but still too early to tell if this will be broken line of supercells or a more solid squall line with embedded supercells . 0-3km CAPEs are bullseyed in 2 areas SC Nebraska between GRI and LNK and over SC Kansas between SLN and Wellington.

The best 850/700mb vv couplet at 00z appears to be well focused west of Lincoln NE so this is a bullseye to take note of. Time to watch the models closely and decide if this is worthy of taking off a 1/2 day to head out northwest. It looks to be a low end MDT risk at this point IMO. Things can change quickly with such a strong upper system though...including the trend of things being further west than what the 12z ETA was suggesting.

 

[matt patterson]

im Curious Brandon, Are you refering to the St. Loius area as a good target on wed the 28th or thurs the 29th??? I dont see any decent possiblity for severe weather in or around St Louis at all for wed. Back on topic, I am having a difficult time figuring out which model soln to jump into bed with in regards to wed... still waiting on 12z to make any further assumptions/crystal ball gazings/wishes....

 

[Adam Atkins]

Deep layer shear progged to be greatest towards the base of the trough, while better backed low-level flow is north near the surface low (Nebraska/SD). I am looking at southern KS if the dryslot doesn't mix out low level moisture too drastically, which the NAM hints at by 00z Thursday. CAPE values in excess of 2500 j/kg very tempting.

 

[Skip Talbot]

The area along I-80 in central Nebraska looks really nice. As Adam pointed out, surface winds are backed in this area. There is a very nice CAPE/SRH combo as well. This is causing some of the severe indices to spike with a sig tor of 5. The WRF also has the CINH eroding by 0z too. My Minnesota bust didn't phase me, and I'll probably be heading west on I-80 Tuesday night if these parameters hold.