6/8/2010 FCST: IL/IA/MO/KS/CO

[Tim Balassie]

I’m wondering if N/NE MO might not be in play tomorrow (8 June).

I looked at the WRF from the surface on up, and the thermodynamics would seem to be there in the afternoon. A lot of moisture/ThetaE pooling along the warm front from S IA SE into C IL. Quite a bit of SB CAPE and at least somewhat notable LIs.

Helicities seem to follow the thermodynamic gradient along the warm front. Kinematics look quite decent – SSE surface winds under backing flow, with 85H winds over 40kts.

Unfortunately, I then looked at upper level temps – ugh. I’m not sure if 5H temps of -6 are going to cut it.

Anyone one else thinking about tomorrow?

TMB

 

[Fred Dearborn]

Been thinking about tomorrow since yesterday,but like you said about upper level temps a problem as well.I wont make a chase decision till early morning.Models didnt look too impressive for Saturdays outbreak the day before,so anything is possible.

 

[Scott Wilks]

I would have to agree that the upper level temps aren't quite there but beings as this will end up a back yard kind of chase day I will decide tomorrow also.

 

[sebenste]

0Z NAM has 2 K CAPE at 0Z along and north of the IA/Mo border, along the U.S. 34 corridor, in southeast IA. As the low level jet kicks in around 0Z, 0-1 KM shear is insane with up to 500 M^2/S^2 in that layer. A tight 700 MB shortwave, negatively tilted, across eastern IA and northeast MO should provide point forcing in this area. Lapse rates will be better than Saturday, and the EFFECTIVE warm front will be the key to it all. The GFS is more optimistic with 3K CAPE through SR 17. Even the 6Z Tuesday forecast from the NAM tonight shows 2K MLCAPE into northeast IL. Wait until morning, but if we get even 2-3 hours of sunshine, we could have an outbreak that tops Saturday. I predicted a significant potential for strong/violent tornadoes from Fairfield-Burlington, IA to Peoria and either side of that axis, maybe a little further west. That thinking hasn't changed in my mind this late Monday night. The 21Z SREF has 50% probs of siggy tornadoes in that corridor at 0Z tomorrow.

 

[Joel Wright]

The 00z NAM is a bit disconcerting regarding tomorrow's setup. First and foremost, the morning convection takes forever to clear the area of interest. This keeps instability very marginal over southeast IA/northeast MO. Second, the winds above H7 are terrible as compared to the new GFS, and previous NAM runs. Bulk shear is about 20-30kts less than Saturday's setup.

With all the above being said, several of the previous runs of the NAM looked considerably better than this latest one. So hopefully tonight's run was a "brainfart".

On the flip side, the SREF model has indicated a very impressive setup over southeast IA/northeast MO over the last several runs. Since it nailed last Saturday's outbreak very well this is definitely something to consider.

 

[Tim Balassie]

Looked at the morning surface chart. Looks like an area of low pressure situated in NE KS with a warm front extending ESE across N MO into C IL. 60 Tds into most of IA and MO, with 70Tds inching into SW MO.

Surface convergence along low pressure axis from a second low in SE SD, basically along the MO River, as well as along warm front. It looks like clearing taking place in S IA. I'm assuming the clear air in SC MO will be displaced by the line of storms working SE across the state.

The RUC has an area of surface low/wave working from NW MO at 15Z to SE MN by 0z, with attendant warm front moving from SE IA up to Lake MI. Looks like an area of backed and convergent flow will be present all afternoon into early evening across SE IA, NE MO into WC IL.

RUC surface stats looks impressive, with high CAPE, ThetaE and LIs working NE from MO into WC IL by 0z, including Tds approaching 75d. Helicities seems to follow the warm front NE, out ahead of the instability axis - not sure what to make of that.

Winds look moderate and backing from the surface up to 250mb most of the period. I particularly like SW 35kts at 85mb. If I'm not mistaken that type of flow pattern assisted storms on Sat.

What I don't like today is the same as yesterday - upper air temps. If anything, 500mb are even worse, something in the neighborhood of -4 to -6 across S IA ans N MO. 700mb temps are just as bad, and I question the ability of updrafts to stay robust in that kind of environment.

Cautiously optimistic about today. I think my first stop would be Burlington, IA.

TMB

 

[Andrew Pritchard]

Really liking a corridor from Jacksonville to Peoria in western Illinois today for a few tornadic supercells. Early morning MCS clearing out very early with clearing skies almost to the Mississippi River. A couple hours is all it usually takes along these Illinois warm front / ofbs and it appears we will get at least that. By 0z the instability tongue should reach in along and south of the warm front from Missouri into central Illinois reaching approximately the Bloomington area. Along the warm front, long looping hodographs will definitely favor supercell development and assuming ample instability return, which appears to be the case, tornado development. Again, given sufficient destabilization 0-1 km helicity values on the order of 200 m2/s2 along the warm front a significant tornado is possible in western Illinois in that general corridor.

Visible satellite trends will need monitored closely over the afternoon, but I think a regional tornado event could be unfolding this evening where the instability tongue intersects the heightened low level shear over western Illinois.

 

[Matthew Piechota]

Think Andrew said it pretty nicely, We are on the road probably going to head to the Macomb area. moisture and shear will not be a problem today. Just need to get the instability up into the area. already have some descent clearing taking place in southern IA. CAPE values of a 1000-1,500 j/kg could be all we need today and with a nice shortwave moving in at H7, forcing should not be a problem.

Today could be another big IL warm front day if mother nature decides to play things out the right (or bad) way.

 

[Warren Faidley]

RE: Colorado.

Initial target: Limon, CO.

SPC Mesoscale Analysis composite indices are continuing to show a regional area of SVR potential later this afternoon as convective initiation occurs over / near the mountains between Pueblo and Denver. Both the 12z RUC and NAM composite reflectivity have a storm or two in the area between 18z-21z. Surface winds are trending to turn E / SE --- and there appears to be a boundary or two moving W / SW from earlier convection to the E / NE.

W.

 

[Jeri Correll]

I think eastern KS has a chance today. Instability is occuring at a good clip, temps have increased 10 degrees in the last hour. Dew points in the 70's currently and CAPE 3000-4000+ J/KG. Slow season for KC metro area but maybe today is the day.

 

[Colin Davis]

As is generally the case, Pritch and I are thinking similarly. For me, though, I'm leaning to the Jacksonville to Macomb corridor. All models have pushed that instability tongue to that area by about 21z, and most recent VIS is clearing things out from SE Iowa into WC IL near the Macomb area. If this clearing continues to expand, I think a couple strong tornadoes are even in play again this evening. It's close enough that I can wait and see this unfold before leaving, as it's still rather conditional. But I'm fairly optimistic at this point for that area.

This clearing is actually coming sooner than it did in IL on Saturday, and the low level winds are better. Similar at 850 and backed at the surface. I'm not expecting a huge day, but I think we may see SPC push that 5% a little northeast again.

The SFC obs in NW/W/C IL are impressive. With a little nose of a LLJ in there and those backed surface winds juxtaposed with low LCLs and what appears to be a tongue of usable instability, tornadoes, with a chance at a strong one, are definitely within the realm of possibility.

I'm staying in Canton for now, but Macomb to Jacksonville is my target.

 

[Michael Riedl]

I agree with you Jeri. Shear, AOA 40 knots is not the best but with such high instability one can not rule it out.

 

[Mike Smith]

Kansas Threat

SPC has issued a tornado watch for much of south central and eastern Kansas.

I believe that if a supercell can develop, there is a tornado threat in Kansas. If it were the old NSSFC days, I would issue a tornado watch 60 either side from P28 to 30 NE of EMP valid 22Z until 02Z (for tornadoes, severe thunderstorm threat will continue until later, I believe). Initiation should be around 21Z.

Per 18Z TOP sounding, sfc analysis, and SPC tools there is a weak low on the front near DDC with some localized backing from around ICT into the Flint Hills. Strong instability on a CFV to SLN axis and breakable cap. There is marginal, but acceptable, veering with height.

There appears to be a weak impulse in the water vapor imagery from EGE to 25 E RTN moving into western Kansas. If that is an actual feature, then it should be the trigger needed to get this going. The TCU from southwest KS into TX Panhandle seems to indicate this is real with PVA and/or cooling aloft.

While I agree with SPC that this will evolve into a very wet (watch for flash flooding with PW's around 2") MCS/Bow with damaging winds, there is an opportunity for a few tornadoes. I would have taken the watch a two counties farther west, however.

Note: This discussion pertains to Kansas only. I agree there is a threat into western Missouri.

 

[Andrew Burnett]

SPC has issued a tornado watch for much of south central and eastern Kansas.

While I agree with SPC that this will evolve into a very wet (watch for flash flooding with PW's around 2") MCS/Bow with damaging winds, there is an opportunity for a few tornadoes. I would have taken the watch a two counties farther west, however.

Note: This discussion pertains to Kansas only. I agree there is a threat into western Missouri.

I agree Mike. The bulk crossover shear and cape both look great. Like you said if one can get isolated I like the odds. Just looking outside, today is easily the most humid it's been this year.. lots of energy out here in eastern KS.

 

[Colin Davis]

Kept this in FCST thread since it is technically more of a fcst still, and because NOW thread only has MO and KS. Move if you see fit.

Currently sitting in Lewistown, IL. Had planned to go to Rushville, but am growing more and more pessimistic with each passing minute.

There is just no surface-based instability (socked in with clouds all day), we're losing our backed surface winds earlier than models predicted, and the cells in W IL in Brown County, which look like crap anyway, are going to prevent any further destabilization and are moving into worked over air, so they won't do either. Lapse rates are just as bad as Saturday in Iowa.

I'm headed home, and I live pretty close to this setup. No thanks this time.