Interesting setup continues to come together for Tuesday. My guess is we’ll break out of our tornado drought and see the first Kansas tornadoes of 2018. There are still a lot of uncertainties with he forecast. The location of surface boundaries is still a bit uncertain, although it does look like the triple point will be in Kansas, it just may shift around a little bit from where I currently have it drawn on the map above. The extent of storm coverage is also a bit uncertain. Despite those uncertainties with the details, the general picture and what we expect to happen is getting more clear.
There are kind of three distinct areas of concern with this setup. Those three areas are the frontal boundary (red line/warm front on map), the triple point area (area where dryline and warm front intersect on the map) and the dryline (orange line on the map).
Storms along the front are virtually a given, but that’s not the storms I’m after. There could be a tornado threat with any storms developing along the front while they’re discrete, but storms are expected to fill in and that should mitigate any tornado threat. The greater tornado threat will be with any storm or tail end developing near the triple point and to a slightly lesser extent with any storms that develop along the dryline. There hasn’t been much in the way of precipitation along the dryline with the models. I don’t trust the models with precipitation though so for now I’m not too worried about it. The more likely area for a storm to develop will be near the triple point. Higher quality moisture will be working into Kansas Tuesday morning, with dewpoints rising into the lower 60’s. During the afternoon a dryline will sharpen up across western Kansas with a well defined moisture wrap around/triple point setting up near I70. This area should be the focus for the greatest tornado threat (boxed in red on the map). As is typical with triple points relative to the open warm sector ahead of the dryline, low level shear will be stronger due to backing surface winds, dewpoints will be slightly higher where moisture is pooling and LCL heights will be a little lower. Below is the NAM 30mb dewpoint map where you can clearly see the triple point and slightly higher dewpoints out ahead of it.
The NAM currently breaks out a discrete storm at the triple point. That scenario would pose the greatest tornado threat with a discrete storm tracking near/along the front. Another possibility is that storms back build along the front and you get more of a tail end to a cluster near the triple point. Regardless of how convection evolves, the best paramaters should be immediately down stream of the triple point. With moderate instability and around 50kts of deep layer shear, conditions will be very supportive of supercells. Additionally, LCL heights will be fairly low and low level shear is well within the range of supporting tornadic storms. Below is a forecast sounding/hodograph from the area ahead of the triple point if you want to see all the specific values of things mentioned above.
There is still a lot of things that can change, but based on current model data it does look like there could be a strong tornado threat near the triple point Tuesday evening. I think it is the clear target for the greatest tornado potential especially when you consider the uncertainty of any dryline storms in the equation. If dryline storms do develop, they also will pose a tornado threat. Hodographs aren’t quite as impressive, but with dryline storms you take the potential for unfavorable convective evolution mitigating tornado potential out of the equation (which could be a problem near the triple point). Right now I think I’m going for the triple point. I like the better parameters and with the uncertainty of storm coverage along the dryline it seems like the easy choice. I will keep a close eye to the dryline and I could easily dive south if I needed to. If a dryline storm did get going farther south, I may drop down to it to help with coverage since it would be tracking through south central Kansas. We’ll see how it plays out. I think one key if your chasing is to be on that triple point storm early. I feel like I’ve seen this movie before and a lot of times triple point storms with setups like this produce a couple good tornadoes early, but then transition to more of an HP warm front demon supercell as they mature. Those are absolutely no fun to chase, especially when you throw a massive convergence of chasers into the equation that can slow your ability to get out of the way. Crowded roads and a warm front demon supercell are a recipe for getting your car shit hammered.
That’s enough rambling about Tuesday for now. There are additional forecast notes on my forecast map BTW. I’ll start taking a close look at Wednesday’s setup later tonight and probably get a quick post up on that. I did glance at it this morning and it looked like the 12Z NAM had a major drop off in low level shear relative to previous runs of the GFS. That is a bit concerning. I’m most likely not chasing tomorrow. I don’t think moisture quality is going to be quite good enough to get the job done. Alright, that’s it for now. Check back later tonight though for an update and I’ll try to get into Wednesday’s setup.