2016-06-14 EVENT: KS/NE/MO/IA

[Jeff House]

Tuesday I like eastern Kansas for a chase target. Short-wave timing is still a slight question, but with such long days the chance of recovery for a second round is there. Outflow boundary may be in play.

Morning rain may be in progress as a lead short-wave moves over the Heartland. Believe chances are pretty good rain pushes away from eastern Kansas by midday. Outflow boundary OFB should result from any early rain. Cap may be strong south of the OFB but looks like cells can get going along the intersection of the OFB and quasi-dry line. Weak surface low may develop in eastern Kansas at the boundary intersection.

Upstairs the jet streak will already be sitting over Kansas. Spoiler could be convection redeveloping midday, too soon, but I think it is not too likely with the warm mid-levels. Also even if the whole jet streak moves out faster, I expect a break between the left front/exit and right rear/entrance regions of the jet streak. New development later in the afternoon seems like a reasonable forecast.

Assuming morning rain pushes away, I like an eastern Kansas target near the intersection of the quasi-dry line and outflow boundary. A weak surface low at the said intersection would add confidence.

 

[Royce Sheibal]

As much as I want to write a 3 page essay on tomorrow's event, the models simply aren't in agreement enough on frontal locations, ongoing convection, and low level winds in order to justify any semblance of a target forecast for me. I won't be able to chase tomorrow, but If I could, I'd be sitting in Jefferson County, Nebraska. SREF shows Hebron to Fairbury as the best target this side of KS for bulk shear and MLCAPE, the 2 most important factors on a day like tomorrow, IMO. If you want to stray into Kansas, the Concordia area isn't too far away and is also looking good.

Again this will all depend so heavily on morning convection that I'm going to wait to do a full meso-analysis until tomorrow morning when the models hit and HRRR is available. Don't trust NAM-4km, it's been a fail-boat this year. Trust the Climatology, Luke.

 

[Ethan Schisler]

Tuesday's severe weather setup seems pretty typical for this time of year. I think there are 2 defined target areas for tomorrow to consider. (1) NW IA/SW MN...4KM has shown for several runs storms firing up near the tri-states border region and moving northeast. This is with the arrival of a ~50 knot mid level jet streak pushing into the area. Surface winds are well backed in this region ahead of an apparent surface low (~15-20 knots). 850mb winds are also quite backed in response to this as well out of the southeast around 30 knots. Pretty good turning with height as a result. Instability doesn't appear as strong up in this region as further south, however values of at least 2000 J/KG MLCAPE should be enough to get the job done, given an appropriate storm mode. Especially factoring in ESRH values on soundings of at least 200m2/s2 in this region.

Target area 2, and the less certain of the two is further south in Eastern (SE?) Kansas. This will be highly dependent upon morning convection I think on how things set up. I can easily see a scenario where the current SPC day 2 risk area ends up being split into two (in other words, 2 targets seeing convective activity and the middle ground being a void, if that makes sense). I digress though! Down here, instability is pretty extreme with MLCAPE values in excess of 4500 J/KG (taking the 4km NAM at face value) and very rich moisture for any-time of the year (75+ TDs!). I think the biggest question as far as this target goes is whether we see any outflow boundaries from possible morning convection that could tip this area towards a higher end severe threat. 4km NAM seems to be possibly picking up on a secondary surface low (?) in this region as its showing a maximum in 0-1km values of ~200+ m2/s2. This combined with the aforementioned thermodynamics creates quite the volatile environment should any storms develop in this region. I think in my mind right now, that is the biggest question. Latest runs of the 4km NAM say storms fire in this region and produces some impressive helicity tracks, however its just one model and I think this will be a developing situation as we go into tomorrow to watch closely.

As far as chasing goes, I will be out chasing tomorrow. Not sure at the moment which target area I'm leaning more towards. Coming from Western Illinois, I don't really have to decide until I depart tomorrow morning. The southern target really has me drooling though at what could occur given the right conditions coming into play

 

[Dan Robinson]

Models have been handling this system poorly, and I'm not surprised that I'm waking up to a dramatically different upper pattern than I thought we'd see. Instead of anything resembling a cutoff low drifting east, it's a shortwave with more of a connection to the main flow. As a result, the upper support is getting pulled rapidly north, leaving just about everything east of I-35 high and dry in terms of deep layer shear. Morning obs seem to suggest an outflow boundary/secondary warm front draped across central Missouri that will likely be in southern Iowa by storm time. If upper support could be counted on, I'd be sticking with that for the rest of the day. Without any decent flow aloft, however, I'm not seeing anything worthy of such a long drive.

 

[Royce Sheibal]

Wow, what a difference 12 hours makes. Yesterday we were expecting a cut-off anywhere from N KS to S SD, and now it will be in Canada by this afternoon. Dan was right, as this cutoff ended up being just a shortwave caught up in the greater flow. There is still a lot of DPVA and good lapse rates associated with this front on the south side, so I still expect storms down into NE and KS, however I think we're stuck with only 2 targets here. You can chase the triple point as it jets northward into W MN, or you can try and pick out the leftover surface cyclone down in S KS or N OK and hope that you get some ENH vort with that area. Wichita has been showing up on most models as a possible target for tors.

As for Nebraska, another day, another low that was missed by the forecast. We'll be running 3K Capes under some pretty heavy lapse rates if we can get some of this cloud debris to clear, so I expect some small hail and maybe a squall line, but I think tornadoes are probably out of the question unless the front stalls out and we can get some ENH surface vorticity due to the influence of the DPVA. Glad I'm not chasing today.

 

[Ethan Schisler]

Yupp. As I've anticipated, things look completely different this morning than they did when I looked over things at dinner last night. I called off a long distance chase since I don't think this system is worth driving 6+ hours for. HRRR shows some decent instability/directional shear along a NW/SE oriented boundary in Eastern Iowa/Western IL later and SPC has pulled the 2% tornado risk barely into this region. Storm organization probably will be an issue with such poor speed/deep layer shear. Although I wouldn't rule out a brief tornado with any storm that can interact with the boundary (this happened on May 9th when I saw 2 tornadoes). I'll be keeping an eye on this as its less than an hour from home for later on. Maybe a local surprise, otherwise its a non-event for me this go around (again). Some years you play your cards the best you can and still can't come up with a winning hand.

 

[Jeff House]

Yes I agree today has a major shift for Day 1. One can plan on mesoscale surface details changing, but such a shift upstairs is pretty dramatic. At any rate things are setting up farther north. Moderators may want to ad SD/MN. I am thinking northwest Iowa would be my preliminary chase target, or at least lunch location.

Morning showers between Omaha and Sioux City should leave an outflow boundary OFB. It should gradually lift north after the rain ends. Look for thunderstorms redeveloping on the intersection of the OFB and the quasi-dryline / Pacific front pushing east from Nebraska. If the OFB surges north quickly, it could start near Sioux Falls. Another scenario is southern Minnesota rain anchors the boundary around Sioux City. Upper level winds gradually strengthen through the afternoon. Low level jet should respond. NWP does not have the LLJ super strong, but the OFB will offer nice low level turning.

Missouri boundary cannot be ignored. It should lift from around I-70 to Iowa by afternoon. Upper level wind shear will be adequate from northwest Missouri north. While models do not back low levels verbatim, we know local helicity will be higher on that boundary. 700 mb temps might be a little hot in Kansas, so one might look from KCMO northeast toward/into Iowa.

Synoptic triple point in western Minnesota is another place to look. At this time I have concerns about too much other rain. If some cells can get some spacing of course just east of the surface low offers low level and deep level shear.

Bottom line: My first choice would be northwest Iowa. Western Minnesota and the MO/IA border are others.

 

[Robert S. Thompson]

After waking up in Dodge City and seeing how eastern KS/western MO is no good, we're heaing toward FDR and hoping for something on the dryline. Though if the cap fails to break it could be a long, hot afternoon...