4/5/10 FCST: NE,KS,OK,IA,MO

[Jacob Ferden]

At this point, I am highly doubtful about the possibility of initiation along the dryline before dusk. A strong cap, as shown by the Lid Strength Index map Skip provided, will make it very difficult for anything to get going, and, as night takes over, will probably kill off anything the does manage to get a start as any developments move to the northeast. I think there just isn't enough of a forcing mechanism to promote adequate lift for initiation, which is a shame when one considers the CAPE AoA 2,000 j/kg, Tds AoA 60 F, and the forecast soundings ahead of the dryline.

I do think the possibilities of significant severe are much better along the warm front in SE Nebraska, northern Missouri, and southern Iowa, but I will not be able to chase those areas tomorrow. I will make a final assessment in the morning, but at this point, there is a pretty good chance I won't be heading out.

 

[Mike Smith]

No change in what I posted last night after reviewing today's 12Z RUC and NAM.

Things looks very favorable from Minneapolis, KS down to about Medicine Lodge for initiation. While LCL's are a little high at 21Z, they are forecast by the NAM to lower by 00Z.

There is a weak short wave initialized by the RUC over Colorado that is forecast to move into Kansas this evening. That is a possible source of the energy for initiation. Water vapor satellite loop shows some evidence the short wave actually exists but is not clear on that point.

However, the water vapor loop as of 1345Z shows the sub-tropical jet from CVS, Stratford, TX; PTT, Ft. Scott,. KS. The inflection point near PTT is moving slowly east. At 5pm Central per the RUC the LLJ will cross the STJ around Medicine Lodge. That crossing point is also a favored area for initiation.

Unless both the RUC and the NAM are completely out to lunch, things look very favorable for supercellular tornadoes in central Kansas, given that initiation occurs. Very large hail is also a threat.

 

[John Farley]

Looks like the models this morning are keeping the warm front a little farther south through the day. Still not breaking out much precip in either target area. However, there is a lot of (probably elevated) storm activity roughly along I-70 in western MO where the blue box is currently in effect, and I suppose if this can keep going through the day and eventually interact with the warm front, there might be a play. But it might also just stay north of the front and elevated.

Given the uncertainty and since the more southerly position of the warm front brings the MO/IL potential closer to me, I think I will just watch and wait and see how things unfold. Difficult forecast, for sure.

 

[Jason Haller]

No change in what I posted last night after reviewing today's 12Z RUC and NAM.

Things looks very favorable from Minneapolis, KS down to about Medicine Lodge for initiation. While LCL's are a little high at 21Z, they are forecast by the NAM to lower by 00Z.

There is a weak short wave initialized by the RUC over Colorado that is forecast to move into Kansas this evening. That is a possible source of the energy for initiation. Water vapor satellite loop shows some evidence the short wave actually exists but is not clear on that point.

However, the water vapor loop as of 1345Z shows the sub-tropical jet from CVS, Stratford, TX; PTT, Ft. Scott,. KS. The inflection point near PTT is moving slowly east. At 5pm Central per the RUC the LLJ will cross the STJ around Medicine Lodge. That crossing point is also a favored area for initiation.

Unless both the RUC and the NAM are completely out to lunch, things look very favorable for supercellular tornadoes in central Kansas, given that initiation occurs. Very large hail is also a threat.

What will also help it this morning convection has laid down a few outflow boundaries that I am sure will help with initiation along the dryline. Things are looking good right now if we can get some of this cloud cover to burn off and give us some good day time heating in central Kansas.

 

[Jim Bishop]

The cap will be very strong along the dryline. Even *IF* a storm fires, it will likely struggle with the cap, given the lack of any large scale upper forcing, probably keeping the storm's life short. Thus, the tornado potential will be diminished. Quite a shame too, wind shear will be very impressive. Certainly can't rule out the chances though....you never know if daytime heating and dryline mixing can get the job done. Just appears unlikely. Very conditional situation.

Not that the setup in south central Iowa looks amazing, but I'd put my money on that area for a tornado today. No dry 850mb advection during the day and a weaker cap. Plus, the cap will be even weaker just north of the warm front. It's no slam dunk, but I think it has better prospects than along the dryline today.

 

[Jim Hunt]

The cap looks to erode rather quickly after 18z and cape quickly jumps to 1000+ a couple of hours later at Redding, IA. Dew points will be still be a bit low (55-60) but it might be a great place to be.

 

[jeremy wilson]

Looks like a nice bulge in central kansas this afternoon. I think somewhere along the dryline in cape thats pushing 3000+ something will fire. We're gonna drift a little north outta Wichita and hope for some magic this afternoon. Good luck to everyone.

 

[Tim Supinie]

One thing that worries me about the dryline play is that any storms that do develop along the dryline are going to move east and run into the cap again. Also, it's a SW-NE oriented dryline. Would be better if it were slightly more to the S-N so multiple cells don't feed into each other. Though it might not be an issue if there's only one cell out there, and another plus of the current (and forecasted) dryline orientation is that it gives more cap-free area for storms to move in and get developed.

I can't chase today, but if I could, I'd probably be leaving for Kingman, KS right about now (or very shortly) to watch what goes down. Yeah, I realize it's pretty conditional, but I can't drive to NW Missouri (which, IMO, looks like a bit more of a sure bet for storms.) I'll probably go out west of OKC tomorrow to see what I can see.

 

[Mike Johnston]

Looks like the potential for development along the dryline is perhaps a bit further south than previously thought - say from Pratt, KS down to Fairview, OK. The intrusion of hot, well-mixed PBL air (into the air mass with deeper moisture) seems most pronounced in that area.

Re: prospect of support from a short wave trough, a kink in the height lines at 500mb over central CO/ northern NM is currently analyzed, so that could certainly play a factor.

Oh, there's definitely a strong EML - but notice a very narrow corridor right along the dryline where NAM output is showing a lid strength index of -1 to 1.

I would say there is a window from ~21z to 01z, in or around the area mentioned above, for possible initiation. Besides signs of a short wave trough, one thing to look for early this afternoon is development/eastward progression off the high plains of steep low level lapse rates. The moisture and potential instability will be there; approach of a disturbance from the west will be the key.

 

[Darren Addy]

Not being able to chase today liberates me much more in picking a target. I realize that the warm front is going to be a focal point for severe thunderstorms, but I'm interested in something I can definitely see before dark and I'm not that confident in what the lift mechanism is before a LLJ kicks in for IA/MO ... therefore, I'd still be targeting the dryline-warm front intersection (where ever that may be). Certainly cap concerns in this area today, but that could work in your favor with getting a truly isolated storm rather than your string of pearls. I'm looking much farther south than I have been previously and I like a line from Medicine Lodge to Newton KS. Splitting the difference, I guess I'd say Kingman. I'd hate to get hung up trying to navigate Wichita around rush hour, so I'd be hoping to guess on the correct side of ICT to be on before the show starts.

Model hodographs look good down there, you are getting a better chance of convective temps down there and you've got a possible shortwave down there timed pretty well, if I'm reading the 700mb map correctly (admittedly a big "if").

 

[Bill Schintler]

Chase Target for Monday, April 5
20 miles north of McPherson, KS.

Timing and storm mode:
Storms will develop after 7 PM CDT. A tornado or two is likely, especially during the early evening hours. Storm motion will be towards the northeast at 25 mph.

Discussion:
This will be an interesting setup today, and this discussion concerns isolated convective development late in the day in the southern extent of a broad area of active weather. More widespread severe weather is likely further north in MO and IA, however the isolated development further south is preferred chasing target. Development further south across southern KS and OK will remain capped with H7 temperatures AOA 8C.

Northward moisture transport will increase dramatically during the afternoon, with SFC dewpoints increasing to 65 F by late afternoon. MLCAPES will increase to 2000-3000J/kg as mid-level lapse rates of 8-8.5 C/km overspreads the moistening AMS. An E/W-oriented WF will sharpen by early evening, serving as the focus for convection. Low-level flow will become increasingly backed after 00Z and SFC-3km SRH’s will increase to 300-400 m2/s2 as a southwesterly LLJ increases to 60 kts.

- Bill
11:00 AM CDT, 04/05/10

 

[Brian Stertz]

Looks to me like the enhanced TOR threat area today is from extreme NE Kansas into far SE Nebraska...NW Missouri...and SW Iowa. This area should be primed for more surface based supercells and tornadoes this afternoon/evening. South of this area...things should be capped off strongly and storms/supercells would be above the cap if anything does develop. 9-10 degrees at 700mb is a death wish this time of year Another area which also looks good for possible supercell eruption this afternoon is between SPI and STL.

 

[John Farley]

For the warm front play, I think northern MO and possibly western IL will have the best chance of daytime tornadoes. The RUC does not move the warm front into IA until after dark, so I think daytime tornadoes are unlikely there, except maybe in the far southwest corner. RUC breaks out some (but not a lot of) precip in NE MO, so I am leaning for a target somewhere in the Bowling Green-Quincy-Kirksville triangle. Still a little unsure; watching convection SW of STL for any trend of intensification, but leaning toward heading up toward the aforementioned target area within the next half hour or so. Unfortunately, that area is not great chase territory.

 

[David Wolfson]

The dryline isn't retreating much and Pratt is clearly out of business, but temps are on the rise. So I would be on the move east to the I-135/I-35 junction south of Wichita. Little change in the ambiguous picture, except that moisture is a few degrees shy of what one would hope. Earlier vis satellite had an indication of an outflow boundary just east of Wichita.

I hope for the IA folks that things improve soon, because anything north of a ST. Joseph/Chillcothe line looks pretty trashy. FWIW.

 

[Jeff Snyder]

I, Gabe Garfield, et al., are currently just S of ICT getting some food, with plans to continue Nward. Clouds have cleared out nicely W of EMP, with strong heating occurring that's resulting in current temps considerably warmer than the 6hr fcst from the 12z NAM. For example, the 18z FCST from the 12z NAM has the 70F isotherm near a line from HUT-ITC-PNC (cooler temps east), while current observations show the 70F isotherm from CNK-TOP-JPL (or JOP, whatever Joplin is). Heck, the 18z ob at EMP has T=79F, while the NAM forecast was 65-70F at the same time. In other words, it looks like the higher-than-NAM-forecast temps should result in a considerably wider CAPE corridor and a larger area of weaker CINH by afternoon. OK Mesonet is showing 65-67F tds in a 2-3 county-wide corridor a little E of the dryline, and these should work northward on 20-25 mph S winds. It'll be nice to see an 18z sounding from LMN (and it'd be really nice to see an ICT sounding, but oh well), though I'm not sure if an 18z balloon is being launched from LMN.

Of course, this doesn't say too much for initiation chances (more about the longevity of convection, in terms of how long a storm has before it "runs into" the stronger cap, should it initiate). Mesonet obs showing due S winds across most the dryline in NW OK, save for one site that's SW wind. We're probably going to meander northward towards the HUT area, but not sure about destab terribly far N.

I'm not looking at IA/MO/NE today, so my lack of discussion for these areas should not be interpreted as a pessimistic forecast for the warm front play.