05/12/04 FCST: S Alley

Well, considering I have nothing else to do... I'll be hanging around the panhandles Wednesday. Would like to see the dryline get its act together. The stuff up north looks nice, but I want to stay closer to central OK, just in case.
 
Wednesday Synopsis- Based on 12z Tues. ETA forecast for 00z Thurs


Instability- Bulls eye of extreme instability over eastern KS, Surface based CAPE over 4000 J/kg and mixed layer CAPE over 3500 centered just south of Emporia. Broad area of strong instability from MCI to OKC.

Vertical Wind Shear- 90 degrees of veering from surface to 700mb across eastern KS and eastern OK. Speed does increase with height, but 850 mb winds are less than 20 kts across eastern KS. Speed shear from 700mb up is available from Emporia northward due to 50kts 500mb winds moving across northern KS. Helicites are not impressive in eastern KS due to the structure if the lower level winds.

Triggers- Cold front basically positioned 30 miles north of I35 from MCI to ICT. Models indicated significant vertical velocities at 850 along the front just north of I35. Also northeast ¼ of KS located on right rear of max wind at 500mb.

Discussion:
Structure of atmosphere supports slow moving supercells. With weak speed shear in lower 3km tornadic activity is questionable. Dewpoints will be near 70 and LFC heights will be around 1800m. Storm will move parallel to the front possibly causing flooding concerns through east-central KS.

Initial Target
Emporia, KS
 
Tomorrow is looking okay in my eyes. Instability is very strong and we finally get some real moisture in here. However, the winds are just crap. The ETA not been very consistent in forecast wind profiles over eastern OK and KS. Thus, what looked like a day with good low-level shear (ETA was putting 200-400 over parts of the area just a few runs ago) is looking more like very poor shear profiles. Perhaps if we some sort of boundary to play off of.. Otherwise, where there are decent mid-level winds (decent by this year's standards, lol) in northern KS, there are very weak low-level flow. Likewise, where the best low-level flow is (eastern OK), mid-level flow is poor. Most disappointing in all of this is the fact that low-level shear is decreasing with each model run. I could take 35kt deep layer given 3000-4000 CAPE and 200-350 helicity. However, by taking away that low-level shear, it looks more like what we've seen lots of this spring -- big 'ole HPs with wet RFDs that have plenty of wall clouds and funnels, but can't produce.

I hope things change. I guess with the way the models have been handling everything lately, things WILL change. Maybe it's okay to have a poor-looking setup now, since there's time for it to change...

Ugh, the ETA forecast soundings look very summer-like. Plenty of juice and instability, but poor wind profiles. Why is July coming early? I want may MAY back!
 
Originally posted by Jeff Snyder
-- big 'ole HPs with wet RFDs that have plenty of wall clouds and funnels, but can't produce.
Click to expand...

This has certainly seemed true so far - overall, wind profiles have remained such that storms have not been fast-moving (there was basically no typical early spring this year), which is nice in itself - but the caveat is that with weaker mid-level and surface flow you also have to take the reality that tornadoes are iffy at best ... and when they do happen they will tend to be short-lived and weak (better hope you get on the storm early and stay on it if it shows any signs of rotation). We can get some neat structure out there, but not much in the way of tubes.

I look for a similar situation to evolve tomorrow - though I am anxious to see the SPC take as of 12:30 here in about 45 mins. If storm motion is parallel to the front, we can hope for some right turning supercells that manage to initiate ahead of the boundary in northeast Kansas and slowly move off to the east. Another fairly easy chase possibly as far as the logistics are concerned, but for now I'm not looking for another Limon, Colorado to happen tomorrow in eastern Kansas, though that would certainly be nice.
 
This chart says a lot, if it should happen verify -

http://www.wxcaster2.com/CENTRAL_ETA_SVR_C...HSWEAT_36HR.gif

while CAPE at 0z looks impressive, and SWEAT is in the 450-500 range in eastern KS, helicity looks very bad ... keeping in mind that helicity and low level shear are elements that can indeed change dramatically overnight, it just isn't overly impressive yet ... helicity is slightly better on the earlier 30hr run, but still nothing to get excited about.
 
Well, from SPC's language in their latest Day 2, it would be wise to sit right on the Low. They make it sound like if you're anywhere else, thanks to the lack of help at the low level, you're in for disapointment. But, like Mike P. says, things could change by tomorrow morning. Well see what happens tonight north of there and how it affects things. What an odd Spring this has been. The next time things line up correctly will be the first.

I've still got tomorrow afternoon off, and am still considering heading southwest into KS, but I think I might have picked the wrong day.
 
Sitting in Hays, KS right now where I'll kick things off tomorrow. Doesn't look like I'll have to go far, even as the risk backs as far as my house in Denver! :lol: Can't think I'll go that far west in hopes of sticking around for Thursday (which I was covered for Friday, so I am FREEEEE to chase it). I don't have a target area in mind yet, although Dodge City has crept into the picture. Will be a bit more specific in the morning when I get a better look at things. AOL's dial-up doesn't allow for a lot of web surfage at speeds, so I'm not going to go nuts, but as it stands right now, I should have a pretty short trip to wherever I go. See ya in the field!
 
Funny, I almost went to Hays tonight. But I opted for Wichita. I-70 could be the slot tomorrow. I can only hope bailing on the panhandles doesn't bite me in the rear. :?
 
Originally posted by John Gnuechtel
I can only hope bailing on the panhandles doesn't bite me in the rear. :?
Click to expand...

Fortunately from Hays, I can be in the OK Panhandle in less than 3 hours! 8) I figured this would be a good starting place since its on I-70 (allows me to quickly adjust west/east), and from there, can basically drop south from just about anywhere in Kansas!
 
Well the 6Z Day1 outlook (issued over 45 minutes early nonetheless) is pretty pessimistic abt tornado chances tomorrow (2% prob, which seems like the standard minimum they use whenver supercellls are possible)... We continue the pattern of not getting any decent juxtaposition of instability and shear. Model forecasts have still be inconcsistent, although both the ETA and RUC agree that the best low-level shear in the warm sector will be in the eastern 1/2 of OK, which is well removed from even marginal mid-level flow... In fact, areas east of I-35 in OK generally have 0-6k shear <25kts, which is less than the typical threshhold for supercells. I'm still holding out hope, however, since the model forecasts have been particularly error-prone lately...
 
I agree, the models don't look too promising for tornadic activity, but as Jeff mentioned, they've been inconsistent. A couple of things make me optimistic for today. One, with the amount of instability we're dealing with, marginal shear can be overcome. Secondly, it's May. And like Tim Marshall says, when it's May, you chase.

The thing I like best is, while the speeds are generally weak to marginal, they are directionally sound for supercells. Also, as the day wears on, the mid-level winds will become stronger over all of NC OK/SC KS, enhancing the chances for long-lived supercells (with decent steering/vent winds).

Right now, my forecast is the same as it was two days ago......find the CF/dryline intersection and play off of that. Better instability (not that the lower areas aren't awesome) will be southward along the dryline into the TX pan, but the winds out there are absolutely dead. Not even extreme instability (I don't think) can make up for the total lack of shear in that region.

Right now I'm liking the Great Bend/Huthinson/Newton corridor, at least initially. Depending on the position of the front, this target will be adjusted north/south.
 
Right now, we're sitting in Grand Island, NE after a long night of driving from NE South Dakota. As of now, I'm thinking pretty much thinking an area just south of I-70; perhaps in the Great Bend area. I notice the 0Z run of the ETA places the highest dewpoints and CAPE further to the East, so I'm hoping these storms can ride the upper air later in the day and interact with the better instability and moisture to the East. As of now, I'd be happy to see a supercell that isn't outflow dominant and undercutting the inflow. Hope I'm not asking for too much.

Tim
 
DDC 3AM AFD:

"THINK TRIPLE
POINT CONVERGENCE AREA WILL BE NEAR LARNED AROUND 00Z"



No reason for me to believe this won't be close to correct, thus, 7am initial target is 30SE of LARNED. Intersection of 281 and 183. No rush today; probably won't leave norman until 12-1pm. Hopefully we can break the clouds up and begin reloading the gun.
 
Seeing as how the cold front appears to have already moved through Larned, Jason Montano and I will most likely be shifting our target a little bit further south and slightly east. As of now, I become less and less excited about today's prospects with each passing minute, but I don't have to work for the next two days, so what the hell.

We will also be leaving Norman at around noon and then hauling butt up to the border. I think we will stay away from the toll road if at all possible. After looking at the latest run of the RUC, it has trouble breaking out convective precip in cental and southern Kansas but has a good area of precip in north central OK.....I am still trying to figure this one out considering the moderate CAPE values and really no cap in KS. I do however like the backing winds out of the ESE at the sfc in KS. Maybe this will help to influence the cold front from advancing too much further south.
 
Lance - the SPC is projecting that the front will slow and then retreat across that region ... this is one you'll have to watch constantly to figure out where it ends up - don't give up hope just yet:

THIS FRONT IS FORECAST TO MOVE STEADILY EWD ACROSS THE GREAT LAKES...WHILE SEWD SURGE INTO THE SRN PLAINS SLOWS THROUGH THE MORNING. BY AFTERNOON...SURFACE LOW IS FORECAST TO DEEPEN ALONG BOUNDARY ACROSS SERN CO. THIS WILL LIKELY ALLOW BOUNDARY TO RETREAT NWD INTO WRN KS / ERN CO THIS AFTERNOON. BY LATE IN THE PERIOD...BOUNDARY SHOULD CONTINUE ITS SWD PUSH ACROSS THE TX / OK PANHANDLE REGION.
 
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