quick thoughts on the convective environment tomorrow
I’ll skip all the synoptic mess, assuming that you can see that on SPC discussions, etc.
I don’t like using CAPE too heavily but it is a nice starting point as always
12Z GFS valid 21UTC/ 4PM CST

12Z GFS valid 0ZUTC/ 7PM CST

12Z GFS valid 3ZUTC/ 10PM CST (nighttime)

The GFS paints a pretty band of CAPE across the central plains, especially towards the KC metro and points southward.
The next step is to compare that to the shorter-term NAM. Since it is right around 3PM now, the new 18Z model is coming in, so we’ll use a different time for this one.
This is the 18Z NAM valid at 21UTC/4PM CST

and 24/0Z

The 3Z doesn’t merit posting here. So why the pretty stark divergence? Both seem to pick up appreciable instability along the n/s oriented boundary to the west of KC, but only the GFS brings up the e/w oriented instability in the afternoon (the NAM does see an element of this — clear from the 18Z run valid at 18Z tomorrow)

especially through the ozarks. Notably, the CAPE here is also further north — which is nice for your target.
I like using the simulated reflectivity as a nice first glance too as well, a product the NAM can offer but not the GFS. When push comes to shove, I love the hrrr model — found here — for that purpose. Really the game changer recently. Anyway, for now, the NAM shows initiation:

Which matches, pretty nicely, its anticipated CAPE field. By 7PM, the model shows three distinct areas of convection: a pre-frontal cell in central MO, a KS/NE/MO cell, and a southern KS cell. For distance I’ll focus on the KS/NE/MO (probably your target) and leave the central MO (the storm of greatest interest to me) alone. Here’s that output,
a little glance at the GFS progged precipitation shows weak initiation, esp in north central KS, an area of higher CAPE in the GFS.
by comparison, the NAM shows a more intense solution:

what this suggests, to me, is that the CAPE will be at least used — that the western band of CAPE is more likely to exist (agreed on in both models) and that the storms should be up and running by 4PM ish. This is in an area of SPC slight risk at the present moment.
First order of business — what is causing initiation here? For this, I’m going to fire up GARP, which is excruciatingly slow this far from school but worth the wait.
This is from the NAM again, and is a plot of surface temperature — in the gradient — and surface winds, plotted as streamlines.
At 21Z, a clear area of surface convergence is present.
This grows out of a surface circulation visible at 18Z

and moves east by 24Z — note the cold pools developed by the precipitation

so it seems that we have a forcing mechanism that should be identifiable too. That’s good to know.
Let’s look at the parameter of EHI — helicity multiplied by CAPE and divided by a massive number (i think 162,800). This is a great measure of storm rotation and initiation, and by far my favorite means of predicting severe weather. The NAM can provide this, the GFS can’t.
NAM 0-1KM shows a finger of >1EHI, but not much, at 21 Z

at 24Z there is an area of intensification to the west:

which is all well and good, but isn’t quite where we want it — after all — that’s not quite where the models prog storm location. Though close enough for what I’ll call “fudge factor” — If i chase, though, I’ll favor southern cells in this mess.
For the record, 3KM EHI at this time is actually pretty impressive:

So that seems to suggest rotation is possible.
Looking more at shear parameters, the helicity is healthy, owing to that surface circulation

which tells us this so far:
1.) The storms should fire by about 4PM along a surface boundary denoted by a wind shift
2.) Storms should have ample instability, especially west of the Mo/KS border
3.) Any storm towards central KS at about 7PM will have decent helicity, and the helicity increases with time.
4.) storms in IA/ NE look less promising
So it seems we are narrowing the target region down a bit towards, say, Topeka — Lawrence, KS esp. points a bit nortward of that line.
Lets look at forecast soundings in that area.
First, the hodograph for OZ near topeka, KS:

which shows a nice right turning profile in the low levels — with a defined ‘sickle’ shape — a positive sign!
The overall profile shows a moderately unstable profile, with decent CAPE — no surprises there.

and the GFS equivalents: Here, a bit east to show the slightly more quick moving nature portrayed by the GFS.
hodo again showing a nice proflie
and a slightly drier, but steeper lapse rate, sounding:

The NAM progs lows LCL heights:

Storm motion appears to be manageable — certainly NOT the 60mph mess of march 22, which I chased.
In the end, what I get out of this is the following plan:
1.) Early: check SPC outlook day 1 — look at tor potential
2.) check RUC/NAM for new EHI forecast
3.) Begin to monitor surface obs for surface convergence
4.) Do a subjective analysis (break out the colored pencils) one that is clear
5.) Watch GOES for cu development
6.) Read SPC MD of area — head out if WW likely, area maximized, reachable and back in under a tank of gas
6a.) Use HRRR as progging tool
7.) play existing storms (no radar on the road for me), using weather radio, storm structure, and a nowcaster as guidance.
A few thoughts:
1.) Initiation by 3:30-5PM along surface convergence
2) Little time for diurnal heating my limit severity
3.) Storms that can form south towards central KS may play out better on current forecast
4.) GFS seems a little hesitant on imitation comparably
5.) want the HRRR run to confirm all above
there is not a thread about this on stromtrack yet — so when the real experts begin to play I’ll see how this analysis stacks up!


