Update on Sunday 4/9

First of all, I should mention that one of our veteran members, Squall Line, was able to intercept a tornado today in West-central Iowa - nice job Squall Line. I nominate Squall Line for the 1st ever Chaser of the Month award, though he's got a bit of a home-court advantage...!

Now that I owe Squall Line a burrito because I lost our bet of under 2.5 tornado reports before dark, I want to point out something. I think severe weather forecasting has come a long way even within the past few years. For example, I was watching the weather channel today (which, if you hold an atmospheric degree, is illegal in some states), and the severe weather expert Greg Forbes, who was a grad students for the legend Ted Fujita, was pointing out how well SPC's "significant tornado parameter" coincided with the 3 or 4 supercells occuring around 8pm in Iowa and Nebraska: see image below. This location was under the gun from about 2 days out, and I would argue that it wouldn't have drawn a moderate risk based on the tools we had 5 years ago. Sure, some improvement is merely from increasing resolution, but that cannot explain all of it.

Anyways, enough with the flattery, we've got an impressive setup for severe weather tomorrow close to the good ol' Badger State. However, as always, there's uncertainty ... For tomorrow, in my mind, there are two uncertainties:

1. Evolution of nighttime convection, and it's impact (through mid & high-level cloud "debris") on surface heating tomorrow.
2. Whether it's worth chasing a potential tornado when you're dealing with the Mississippi River, hilly terrain and ~50mph storm motion.

My Go Zone forecast is below and here's the explanation for it: the surface cyclone, currently fairly broad will consolidate into one center by later tonight. The supercells and other small convective clusters look to merge into an MCS-looking blob and carry on north and east through the night. The GFS looks like it's suffering from a case of an underactive convective parameterization scheme and generates splotchy precip covering Iowa, Minn and Wisconsin for the next 18 hours straight. I think this model's out to lunch - I like the NAM a lot more.

At the surface, the cyclone's triple point will move northeast with the mean flow and will be positioned near Willmar, Mn at 18Z and Hayward, Wi at 00Z. Looks like convective initiation will be around 20Z west of the Mississippi and the storms may be discrete all the way down the cold front due to the high sfc-500mb shear and some veering even on the front itself. However, the best shot for discrete cells may be closer to the triple point, like today, which is why I'm thinking of going a bit north towards the warm front and backing surface winds.

Now it's time to figure out whether its worth braving the trees, hills and river crossings to chase...