3/23/09 FCST: NE, KS, OK

[Rocky Rascovich]

Jeepers! Everyone's getting crazier than a bunch of hunchbacks at a limbo contest over this set up.. must be the SDS going in overdrive. I can relate.
I'm a little perplexed over the GFS speeding up the system like it is. I'm not buying into that yet as the other models including the Euro, all hold it back some.. which would put the western half of OK. under the gun.

My biggest concern is instability.. this seems to also have been scaled back, and this may be a plausible scenario giving that despite recent rains over north central TX. area's south of there didn't get as much and they are parched, that would probably have something to do with this BUT, the 850mb. jet is flowing gangbusters, advecting that gulf moisture northward, so that may compensate. Speed and directional shear are outstanding for much of Okla. from 18Z on until late evening. I do see more of a cap with CINH values on the increase.. that's something I'll be watching. Also, these subtle waves that come through over the day before, and into Monday morning, this COULD lead to subsidence in the wake of one that comes through.. that could be the reason the NAM has CINH values as high as they are during the afternoon hours on Monday.

So... yeah, the dynamics look great, almost scary... my original forecast of a couple of violent tornadoes is not out of the question IF we can get the moisture and IF storms can stay discrete long enough.. with all the forcing going on.. you can bet that a raging squall line will soon result by mid evening.

As a few have mentioned earlier, the play over southwestern Neb. and even NE CO. (if the NAM, Euro and UKMET verify) is something to really consider. It's almost a given that with the cold core set up, the strength of the surface cyclone, good shear and dews in the 40's. Low topped supercells will almost certainly form and tornadoes will be a high probability, and, they won't be moving near as fast. These could be real picturesque, but my guess is it will happen early (maybe as early as 17Z) along the I-80 corridor from Grand Island on west to the I-76 junction. The GFS though has this scenario happening much further north, like, Scottsbluff and on up into SW SD. That would be too far for me. Right now, I'm seriously considering in biting the bullet, roll the dice and head up to Goodland Sunday night, maybe even McCook, and play the cold core. I have a big feeling this will play out.. or, I'll be stuck in a fog bank and hearing reports of everyone gathering at my farm witnessing a wedgefest northwest of Piedmont.. of which case, have a nice padded cell ready for me.

 

[Chad Cowan]

Looking over this thread I would like to point out that, as I've learned over the years (mainly from Jeff Snyder's contributions), instability is only half the equation of updraft strength. As evidenced by 2/28/07 and numerous other high shear/low CAPE situations, vertical pressure gradients can provide the extra kick needed for tornadogenesis especially with dynamic systems such as this. I definitely understand the chaser-hatred expressed in this thread given the storm motions that generally accompany these type of high shear/low CAPE type systems but it's all about finding that perfect balance between the two and the foresight/luck to position oneself properly. I'm not convinced this will be an 'outbreak' day, but given the great dynamics I wouldn't be surprised to see a few tornadic supercells from southwest NE into OK. Lack of quality surface moisture (and subsequent high LCL's) in the warm sector (or GFS' mild sector) will likely be the limiting factor for long-track (and probably full condensation funnel) tornadoes in this case. The one upside to the meridional steering flow is that it will keep the storms within the zone of highest instability for longer than zonal flow would... unless of course we get an optimal right-turning supercell, in which case it will optimize itself right out of play.

IF the low-level moisture advection is higher than forecast AND early/mid-day cloud cover is limited across the warm sector, I would definitely consider playing away from the dryline from south-central KS (near Wichita) southward into central OK (near OKC). Here you would have a better chance of staying discrete given the very strong forcing along the synoptic boundaries due to the the premature ejection of the shortwave and the further south you go, you get into better surface moisture and hodograph shape. Both the GFS and WRF have been consistent in breaking out precip in this area but like I said, this is all contingent on enough instability developing eastward to sustain surface-based updrafts.

I'll be available for nowcasting, PM me if interested.

 

[jamesmseitz]

Ok some explain to me why they think this is still a good set up. Really I want to know because where I sit..... Moisture is lacking, cloud cover seem very likely, instability is moderate at best and most of the forcing seem to be in the colder sector. Do I think there will be some tornados, yes , but I do not understand why they are saying that is going to be significant. Am I missing something..... If so, what.

 

[Derek Weston]

Really narrow axis of CAPE per the latest NAM, with only a few pockets pushing 1200 J/kg. Latest NAM (0Z) also depicts a big fat line of convection fired off the dryline by 0Z across much of Kansas into N Oklahoma (not surprising considering 500 flow there) -- while I don't exactly have full confidence in the NAM's precip prediction model, it does make me wonder. Our storm motion will be nearly parallel to the dryline... though we ought to have anvil level winds that would perhaps keep the storms from seeding ontop of each other. (course, the precip model doesn't seem to think so)

jamesmseitz -- it's all pretty dicey if you ask me. The reason for excitement with this system, if you ask me... are the shear dynamics it offers. Maybe on top of the low early on, looks interesting... that or down in SW OK, if I were going to play.

 

[jamesmseitz]

I am going to go because I have Monday and Tuesday off but it looks iffy to me. I do like that it looks good on Shear but as well all know we need everything for a great day. I was just begining to wonder if it was me or is it that we all have the bug and are crossing our fingers and not looking at everything. That is all. Thank you Derek Weston

 

[Chris Lott]

I'm still liking the area along the Red with the speed and directional shear. I really think the 60 dews will verify on Monday, maybe expanding a narrow forecasted area of minimal CAPE. I still look for storms to form ahead of the dryline along or just north of the Red River and go tornadic early on before everything turns linear.

 

[CZandbergen]

The latest NAM run is really a downer. I was thinking somewhere on a line from Enid to Woodward looked interesting the last few runs, but now not so much. Guess I will just get up tomorrow and hope something interesting happens in the runs over night. It does look like the NAM is picking up the acceleration the GFS showed in the 18Z run. Not sure that is a good thing.

Then again, we have a good 48+ hours for things to change.

 

[jshields]

the 0Z run of the NAM has sped up the system up now, just like the 18Z version of GFS did. the surface low is now shown in central nebraska by OZ tuesday where it was in western nebraska on the previous runs. there seems to be a larger area of smaller CAPE, but overall the higher values of CAPE arent as large. for the best chance of tornadoes i'm thinking south central ks down thru central ok. the winds really veer with height down there. up in central/south central nebraska theres also a pocket of higher cape(=1250 j/kg), but unfortunately the winds aren't veering with height as much there with the 500 mb winds out of the south. its curious why the models are speeding up everything up now. i wonder what the 0Z runs of the gfs and european models will show? much like most everyone else is saying, i guess its wait and see what happens on monday

the OZ GFS run is out thru monday night now and it shows a little bit stonger of a low and maybe just a tad slower again. the cape still isn't there though until 06Z tuesday when it really jumps up to 1750 j/kg along the ks/ok border. its starting to look more and more like it might be an overnight show for any tornadoes in ks/ok.

 

[jamesmseitz]

These last few runs make me think should I save the gas money for later.... I just look at archive run for march 26-28 of 07 hopeing that the narrow band that happened that day was much like we are seeing now..... I was bummed out. I begining to really think that this will truely like I said before..... Nothing more than a light show.... Hope not and we will wait and see.

 

[Mikey Gribble]

I'm not terribly upset with the latest run. I don't see a whole lot of difference in the setup along the KS-OK border and south of there a ways, which is the main area I've been focusing on. Obviously we have a significant lack of instability, but it's March. That's what happens in March. It does look like there is better directional shear over this area now than there was a couple days ago due to better veering in the 700-500 layer. Low level shear isn't shabby. With 850 winds screaming out of the south 0-1km SRH is well over 100m2s2 over most of that area (I looked at the Medicine Lodge sounding). I've only spent the last ten minutes or so checking this out, but I'm optimistic and I'm sure I'll chase.
Another thing that hasn't been mentioned much and we should be greatful for is that the models consistently break out precip near and just south of the OK-KS border.
I am going to get into my real forecasting tomorrow when I actually have some time to sit down and hash things out.
If I was forced to pick a target now it would be just northeast of woodward, Oklahoma 15-20 miles.

 

[Craig McPeck]

If you would like a good map to look at dew points with animation;

http://www.spc.noaa.gov/exper/mesoanalysis/frames.php?sector=4

60 degree dew points moving into southeast texas

 

[Andrew Stoller]

I'm seriously not liking this trend of speeding the system up, along with less and less instability.

 

[Brian Stertz]

Have some surface ridging going down towrds N. Gulf this morning. Not so sure about good moisture quality for sure Sunday...and now Monday too. That wildcard may be the spoiler for the Monday chase. Still forecasted to be a very strong wave so can't totally blow off things just yet.

 

[Mikey Gribble]

There's no reason to be upset guys lol. Yeah the moisture sucks and we really need low 60 dewpoints with temps in the upper 70's, but it's not happening.
On the other hand, in every respect the shear is quite good (deep layer, SRH, 1kmSR, etc). The instability obviously sucks, but it's sucked pretty bad before when we've seen tornadoes. I'm not saying there are going to be tornaodes, but I honestly think there's a 65% chance at least that we'll see tornadoes on Monday. Dewpoints aren't good and the level of instability sucks, but there isn't anything we can do about it. It doesn't suck bad enough to keep me from chasing.

 

[Skip Talbot]

Central NE still looks a little interesting. Check out that 500 mb vort max right next to the instability axis. The dewpoints are very marginal across the whole dryline, but up in NE you might see the best instability and highlest lapse rates where the air is coldest aloft by that cutoff 500 mb low.