5/13/09 FCST: IA/IL/MO/OK

[Mike Johnston]

The RUC us indicating some sort of wind shift line well ahead of the cold front which will likely be the focal point for isolated development in E MO/W IL. If this does verify then I think we could see some interesting things today. The RUC also shows the line of storms north of I70 rapidly moving into Illinois clearing out much of E MO/far W IL by 11am and points east by noon. I am slowly becoming more optimistic about today. However I still have no defined target we will be blasting east on I70 at 9am planning on heading towards Columbia or St. Louis before adjusting.

Edit: After seeing the new RUC it appears Columbia, MO will be the place to be, it breaks out one lone supercell that just sits in C MO all afternoon with CAPE 3000+ j/kg and 70F dews, it could get pretty wild in this area around 2-3pm. I also like to see the cold front hang back in NW MO and W Iowa all day with supercells erupting all along the 'wind shift" line in E MO and far W IL.

Yes, sure are signs of a pre-frontal trough that one would like to be out ahead of. Surface winds look to be veering badly behind it. Looks like around 21z, an area around Osage Beach, MO would be the place to be - just along the convergence associated w/ noted wind shift. Plus, robust instability w/ CIN just starting to erode. In the hours leading up, looks like this area will have ample heating and be on the nose of theta-e ridge.

 

[Chad Cowan]

12z RUC showing high instability and not much of a cap at 21z, looks like storms firing off away from the cold front is a real possibility:

 

[Tom Dulong]

Visible satellite and OK area radar data indicate OFB from last night's MCS now runs from Coffeeville - W of Tulsa - N of Oklahoma City. West ptn of this feature appears to be moving back northward. Question is how much of boundary will be left from strongly-mixed boundary layer by initiation time late this afternoon. I'm thinking that perhaps Enid eastward to Tulsa and north might be best initial target zone. Have to hope you get on first storms early, because everything will line-out quickly.

 

[Joel Wright]

I'm really liking the weak surface low forecast by the RUC in northeast Missouri by late afternoon. This keeps the winds backed at the surface over west-central Illinois. There could be an outflow/differential heating boundary setup near this area also, leftover from the morning junk. RUC also forecasts CAPE in excess of 3,000j/kg with 0-3km helicity near 300m2/s2. If this comes into fruition we should have some nice supercells to chase in this area.

Our original target of Macomb looks pretty good. May have to head a bit further south depending on how the morning stuff evolves. My gut feeling though is west-central IL is the place to be!

 

[CZandbergen]

Visible satellite and OK area radar data indicate OFB from last night's MCS now runs from Coffeeville - W of Tulsa - N of Oklahoma City. West ptn of this feature appears to be moving back northward. Question is how much of boundary will be left from strongly-mixed boundary layer by initiation time late this afternoon. I'm thinking that perhaps Enid eastward to Tulsa and north might be best initial target zone. Have to hope you get on first storms early, because everything will line-out quickly.

I agree. Just finished drawing my second map of the day and at this point I am planning on Enid as my target. Plan to leave Tulsa about 1PM and stop at I35 to evaluate data. Will have to keep a close watch on that OFB and how it interacts with the forcing later in the day. Sheer is going to be marginal, but if you get on the right cell before this thing lines out early evening I think there is a chance that it might produce. Tds in the target area are coming up nicely. Just have to wait for something to break the cap.

 

[John Farley]

I think with all the model disagreement there are several possibilities. The one I like the best, both meteorologically and for my ability to chase it given my time limitations today, is the potential for what might happen when the MCV moving up from NW Arkansas intersects any remaining outflow boundaries from the convection now occurring in central IL. This could lead to quite a show south of I-70 in IL and maybe south of I-44 in MO - but the latter is TERRIBLE chase terrain. IL isn't great either once you get south of I64, but it is a lot better than the aforementioned MO area. Strong storms have broken out SE of SGF already - I would rather they had waited until the MCV got farther up toward STL, but we will see how this evolves. FWIW SPC gave pretty prominent play to this MCV in their morning outlook.

Another possibility, as others have mentioned, is convection out ahead of the cold front around the Columbia-Jefferson City area. This is too far for me to get back in time for my evening commitment, so I will pass on this. Also once you get south of Jeff City it is nearly impossible chase terrain. Been there, done that!

A third possibility is that the elevated stuff just north of STL backbuilds enough to get on the warm side of the warm front and become surface-based. This would be good for the chase opportunities in the area between STL and Quincy and could keep the much-discussed Litchfield target in play. Not sure if there will be enough instability here after all the overnight and morning rain, though - but the models do pedict pretty good resurgence of instability this afternoon.

Given the nearness of and uncertainty between the first and third areas discussed above, I think I will just watch things from home in Edwardsville and if something decent pops either in the northern or southern target that I can get to and back from by around 6 p.m. (when I have to be back to leave for that Beach Boys concert), I will head out for a more or less local intercept.

 

[Tyler Burg]

RUC spitting out some extreme instability in OK, area of 6500 j/kg at 12hr...just insane

http://twisterdata.com/index.php?prog=forecast&model=RUC&grid=255&model_yyyy=2009

I guess that link doesn't work, can't get the URL location on this computer, sorry.

 

[Colin Davis]

The last two RUC runs have really made me think hard about WC IL again. Jacksonville area back S and W toward the river is my favorite reachable area. That weak SFC low that Joel mentioned earlier has been staying there, and RUC has backed surface winds in that general area until at least 1z, with a nice tongue of instability pushing its way in there. Give me a boundary as a focal point and I like that area a lot.

I'll be heading down 67 toward the Jacksonville area momentarily.

 

[Jeff Snyder]

RUC spitting out some extreme instability in OK, area of 6500 j/kg at 12hr...just insane

http://twisterdata.com/index.php?prog=forecast&model=RUC&grid=255&model_yyyy=2009

I guess that link doesn't work, can't get the URL location on this computer, sorry.

Tyler, you may want to be a bit careful with RUC 9 and 12 hr forecasts of CAPE. I've noticed that, on many days this year, the RUC is vastly overforecasting surface moisture (i.e. 2 m Td), which in turn is leading to a significant overforecast of CAPE. I'm not sure if this is a new bug or something, but I've seen it on many days this year. It's most prevalent at the longer forecast hours, which isn't terribly surprising.

I'm getting sick of the dislocation between moisture (and, thus, largely instability) and shear the past week (and through next week). Another relatively weak flow day in OK with shear that is only marginally supportive of supercells. The extreme CAPE certainly will help ensure intense updrafts (and stretching of tilted vorticity), but we'll have to see how quickly the front sags southward. I'm still hoping for dryline initiation in SW Oklahoma, where there's a better chance of seeing some backed sfc flow (and where the front has the least chance of undercutting the storms).

 

[Derek Weston]

Seems to be a good bit of capping now over central Missouri. CAPE building nicely... clouds starting to burn off here... nice shear even if a bit veered at 850s. The cap, for the time being, is a good thing... if we can hold out an hour or two here we could have a pretty impressive environment for initiation.

edits:

And here we go with a SPC MD... latest mesoscale analysis data shows cap weakening.

 

[Mike Hollingshead]

In Macon MO now and actually getting tempted to drive back north and west a bit. Outflow from these storms has a boundary kind of going se to nw into southern IA. It's making me think of that other day in this same area with sw winds bisecting a nw-se boundary. Only this time the moisture will be there in time. Could completely see something trying to ride that ese as it lifts some. RUC really focusing in on that area as well. Hmm.

Edit: MD out for that area now. http://www.spc.ncep.noaa.gov/products/md/md0812.html

 

[Ryan Wichman]

Will be heading west within the hour. Looks like the destabilitzation is occuring back into MO with good backing winds just on the west side of the Mississippi. Probably will cross in Quincy and see what the storms have to offer then. GL

 

[jshields]

In Macon MO now and actually getting tempted to drive back north and west a bit. Outflow from these storms has a boundary kind of going se to nw into southern IA. It's making me think of that other day in this same area with sw winds bisecting a nw-se boundary. Only this time the moisture will be there in time. Could completely see something trying to ride that ese as it lifts some. RUC really focusing in on that area as well. Hmm.

Edit: MD out for that area now. http://www.spc.ncep.noaa.gov/products/md/md0812.html

i'm actually in macon, mo too!! i think i am going to sit tight for now. right now there is a shower moving through. is that ofb also the "warm front" that the spc was talking about in their md?

 

[Chris Allington]

We are in the moberly, MO area... continuing to head north toward Macon. Hoping for something to initiate and latch on to this warm front/ofb

 

[Dan Rupnow]

19Z RUC paints a tantilizing picture in the tri-state area of IA/IL/MO around 23Z. 0-1Km SRH of around 450m2/s2 juxtaposed over CAPE of around 2,000 J/Kg! Hope that isn't too good to be true.