4/4/09 FCST: TX/OK/KS

[Connor McCrorey]

Saturday looks to be at least a decent chase day as of right now. The ECMWF is, of course, slower than the GFS, which is something I am very glad to see. If the GFS verifies, a dryline will probably setup somewhere around I-35 Saturday afternoon. With 60F Tds up to S OK, moisture shouldn't be too much of a problem further south, although it would certainly be nice to see some better moisture return. The ECMWF is quite a bit farther slower and farther west, which would certainly be nice from a chase standpoint. Overall instability doesn't look great, but it could be worse. So once I get out of the ACT Saturday morning, I'll most likely be chasing

 

[Adam Lucio]

Yesterdays GFS runs took a dump on the setup IMO, with Tds barely in the 50s and the main trough out of there by the end of the period. Right now im scrapping my plans to chase this one. It looks like stuff wouldnt get going till after dark. The shear is there though, but right now this looks like another waste of a good wind profile setup.

Still something to watch though, if later runs slow the system back down we may get juice to work with.

 

[AndyGabrielson]

I'm not sure if I would write this one off just yet. We all know the GFS has been all over, I won't make a final decision til Thursday or even Friday. I think we will see a little better moisture return than what the GFS has at this time, it has been slow with moisture on a couple of occasions now. Like Adam said, if this system would slow down we could really have something here...

 

[Darren Addy]

The NAM has the 500mb low a lot farther south than the GFS does. Obviously, the farther south it is the better the moisture return environment will be (and the better for southern chasers).

 

[Tony Laubach]

I think a farther south setup will do better, but overall, I don't see a whole ton of change in the moisture profile that will make this setup any different from what we saw last week. Obviously the dynamics are good, but the moisture profile is iffy. Its not a terribly setup in terms of severe weather chances, so I'd definitely go out if things fell into place, but I wouldn't be expecting a lot different that what was seen last week if things continue to look this way.

 

[Ted Keller]

I checked a point sounding in central Oklahoma (on 12 GFS) for 00Z Sunday and noticed a fairly deep saturated layer from 700 to about 450 mb. I hope a cloud canopy doesn't become an issue.

Otherwise, this morning's runs do look better than yesterday's. Higher instability. Interesting split in the jet over Oklahoma. 140 kt 250 jet over north Texas.

This will get me out to test new streaming equipment at the very least!

 

[Andrew Stoller]

With storm after storm and cold front after cold front coming through the continental US every 2 days or so and sweeping out the northwestern gulf, moisture return is going to be a problem for the central plains with any decent kinematic trough. It would be nice if we could get a lull in the pattern for a week or so and then get a big trough to slowly dig into the western US and be able to pull up a deep, rich airmass into the better kinematic environment, but I don't see that happening in the near future, especially for Saturday.

 

[Wesley Luginbyhl]

I agree with Andrew, moisture return is going be a major issue. Compare the 12z NAM 84hr to the 12z GFS 84hr. The GFS is being much nicer with the return flow at that point. The GFS barely gets 60 dew points to the Red River area in time for Saturday. The 50 Dp line is at the Gulf on Friday evening on the NAM. Unless some changes occur I dont see anything worth while coming out of this system on Saturday.

 

[nickgrillo]

Right now im scrapping my plans to chase this one. It looks like stuff wouldnt get going till after dark.

Where do you see this? GFS has been consistent with bringing the mid-level shortwave trough into the warm sector during peak heating, rapidly initiating convection along the dryline by 00z. Latest GFS runs also project a more negatively-tilted orientation of the trough, with 50-70kts of SW 500mb flow overspreading the warm sector by the late afternoon. GFS has also been trending with the ECMWF by slowing (placing the surface cyclone further west at 0z) down the system. As far as moisture is concerned, I do NOT see much of a difference between the 4th and 3/23; even with the 55 Td isodrosotherm peaking into central KS, it will still yield enough surface-based instability for supercells given the degree of deep-layer shear. Now, I'm not saying we'll have a slight problem with boundary layer moisture return, but with the strengthening low-level flow, I don't see why we couldn't see >50 Tds into KS by the time the shortwave moves over the warm sector.

 

[Michael O'Keeffe]

Well after looking at the NAM and the GFS I wouldn't discount far S OK/N TX. With the powerful negative tilt trough and that nice split flow at 500mb over the Red River will help lead to great directional shear, that with a decent S 850mb winds. The dewpoints should be able to reach the 60Fs fairly easy south of the Red River, which is good enough for tornadic supercells. Cape will be OK with over 1000 j/kg over the I35 corridor and just west. Though it isn't great as we begin to move into the main part of the season. Also based off the 12z GFS the moisture appears deep enough to keep the storm sustained. Though it may seem impossible to get 60F dews from the Gulf Coast to the Red River in about 18 hrs, yesterday the dews were in the upper 30s over southern Oklahoma with low 50s on the Gulf Coast that morning and later that day dews reached 58-60F over much of Texas and S OK, so it is possible, with that I'd likely chase.

 

[Adam Lucio]

Where do you see this? GFS has been consistent with bringing the mid-level shortwave trough into the warm sector during peak heating, rapidly initiating convection along the dryline by 00z. Latest GFS runs also project a more negatively-tilted orientation of the trough, with 50-70kts of SW 500mb flow overspreading the warm sector by the late afternoon. GFS has also been trending with the ECMWF by slowing (placing the surface cyclone further west at 0z) down the system. As far as moisture is concerned, I do NOT see much of a difference between the 4th and 3/23; even with the 55 Td isodrosotherm peaking into central KS, it will still yield enough surface-based instability for supercells given the degree of deep-layer shear. Now, I'm not saying we'll have a slight problem with boundary layer moisture return, but with the strengthening low-level flow, I don't see why we couldn't see >50 Tds into KS by the time the shortwave moves over the warm sector.

Hell Im not sure which run I was going off when I said that. What matters its not showing up now and things do look better but still questionable. The red river area looks like it might be the best play right now. Thats another 4hr drive probably for me, so I wont commit just yet.

GFS has begun to trend with other models thought. moisture and CAPE might be a wee bit better than on 3/23 so lets keep the trend of slowing down a bit.

 

[Sean McMullen]

I've had my concerns about this system but it hasn't been the instability as much as it's been the vertically stacked nature throughout the levels. Earlier runs have been kicking the upper wave out ahead of the surface low puting the vort max in eastern Kansas with the surface low back in wesern Kansas. However, the latest 18z GFS holds back the vorticity which would create better lift closer to the surface low. Along with that a very healthy approaching jet max could give you all the lift you need without the crazy instability. A lot like what happened in Nebraska on the 23rd. Shear vectors are going to be more perpendicular along the dryline furhter south into southern Kansas and Oklahoma and that would place it in an area of somewhat better moisture so this setup is certainly looking better as of right now.

Sean

 

[CZandbergen]

Not to distract from the VIP area chaos (which is pretty funny), looks like this system is a bust in the last few NAM runs. Moisture is hanging further south and CAPE looks really limited. Looks like the show (if any) may be south of the red river and after dark I am afraid.

 

[Dustin Wilcox]

The show will be the snow storm across NE/SD. If there is any severe show (not likely) I think it will be in NE KS. The 0Z NAM is much faster with things overall and has things about 100 miles further East than the previous runs. The 18Z looked semi chase worthy across NC and NE KS, with moderate CAPE values thanks to super steep lapse rates, and the obvious favorable dynamics provide for more than adequate shear values across the entire "warm" sector. The 0Z took most of the positives about the thermodynamics from the 18Z run and threw them out, however given the nature of the system I'll keep a close eye on the sfc low, and if all else fails I'll likely drift North and play in the probable blizzard...

 

[Mike Hollingshead]

Certainly some interesting forecast soundings in se NE by 7pm.

Nebraska City

Falls City


Moisture will no doubt be pathetic right behind the monster system on the east coast by then. I think I'd settle for a 50TD on this one, but that might be a stretch. I don't recall what the dews were for that last system that produced up here but sort of doubt they'll be even that good this time. Even at that, for those attending the symposium in Lincoln this day, it might be a no brainer to chase given the location.