2016-03-31 EVENT: MI/IL/IN/KY/TN/MS

[chrisbray]

Surprised no one has posted this yet, must be people are still focused on today's event. I have been watching this for a while. Still not sure if I will go or not.

A fast moving upper trough and surface low with trailing cold front will move out over IL/IN/MI tomorrow afternoon. NAM has been kind of an outlier in terms of system speed and location for days now, but the Euro and GFS seem to have slowed down to match up with it a bit as of late. My target, should i choose to go, will be the IL/IN border, as far North/West as possible, so I will focus on that area. NAM insists on bringing 60+ Tds as far north as Chicago (we sit here 24 hours in advance with a dewpoint of 41, so we shall see), and showing much more cape than other models (what else is new), 1500-2500 North to South, with 70-80 knots of bulk shear progged!

It isn't all roses, however, as NAM is kind of an outlier as having a trailing, secondary surface low feature over N. IL at 21z. That helps to keep surface winds SSW across this area, but if the center of the low is farther NW, winds will be much more veered and the shear will be almost entirely speed without direction. Another negative will be very fast storms speeds, up to 55 knots (!), as well as LOTS of forcing, making me worry this will rapidly become a squall line. ON top of that, we have to see how early morning rain/convection goes before we know if this area will destablize under the sun or not.

I am hoping models continue the slowing trend as the day approaches, giving more room for a warm sector closer to me.

 

[Ethan Schisler]

I had been watching this event as well since it was fairly close-by. However I think I may end up sitting this one out, despite its somewhat close-proximity to home. We have a fairly strong surface low (~992mb) that will be pushing through Northern Illinois around mid-day. The timing appears somewhat fast to offer up a favorable solution further west, so I think if I were chasing I would target somewhere just north of I-70 in Southeast Illinois into Western Indiana. Terrain into Indiana can get kinda sketchy, but Eastern Illinois has some fairly flat terrain to work with.

As for meteorologically, I don't really like the fast timing of the surface low, which seems to keep surface winds veered from the SW and most of the wind profiles I looked at were fairly unidirectional. Instability looked fairly decent on the NAM this morning with SBCAPE values of ~2000 J/KG along with pretty good moisture (low to mid 60s). The wind fields are going to be the biggest issue that I see as far as getting a significant tornado threat out of this. Otherwise if we had our typically backing of the winds with the approach of the surface low, we would be looking at a much more sizable event. Maybe things will change between now and tomorrow, however right now I'm probably sitting this one out. Good luck to those that venture out.

 

[Matt Magiera]

I've been watching this for the past several days as this has slowed, and I'm thinking of giving it a shot since I'm off work and have no classes tomorrow. I'm liking the NAM as of recently, bringing good dewpoints into the mid 60's across the southern half of Illinois and modest instability of around 2000 J/KG. If diurnal heating and morning crapvection doesn't mess with this too much, there could be a shot at a few tornadoes. I'm probably going to end up leaving around 9am for a target of around Effingham, IL. The wind profiles aren't particularly impressive and are largely unidirectional, however a lot could change especially with this recent slowing trend. I'll probably end up sniffing out any leftover mesoscale features or outflow boundaries as a focus for better supercell development.
Here's a sounding of right along the IL/IN border at 21Z from the latest 4km NAM:
Lapse rates look alright, with "eh" shear values. I'm not particularly impressed, but there's a shot there.
Overall I'm going to keep an eye on this and watch it as the 00Z comes in and make a final decision on whether or not to chase tomorrow. I probably will give it a shot simply because I have nothing to do tomorrow and there's just enough a chance, but this isn't something I'd give up a ton to chase for.

 

[Robert Forry]

Thanks for posting this Chris. Like the rest I too have been watching for the last several days, figuring we'd at least get a shot of severe up here in the Mitten. While that's a possibility, I believe the real TOR threat is down in the delta where the parameters are better, and that said, the latest HRRR shows things clearing out nicely in NW IN just after lunch, allowing the atomosphere to destabilize before storms refire in clusters from SW MI back into NE IL around 1930-20Z.

Ft Wayne, IN

That said, without backing winds at the surface my thoughs are that this will go linear pretty quickly after 21Z, unless, that is, what I'm seeing are storms firing up on an OFB leftover from morning convection. Taking the PM off and will target South Bend/Elkhart to begin.

 

[Jeff House]

Southern target is the forecast outflow boundary OFB in Mississippi this afternoon. Tennessee low levels may be too veered. However the OFB will locally back surface winds. Also the southern stream jet stream ramps up toward 00Z. Speed and directional shear should be excellent over the OFB likely in Mississippi.

Later this evening I would look for some damaging straight line winds from Mississippi into Alabama if the HRRR is correct. Any supercells on that OFB may expand into a bow echo or QLCS and race east from there. Apart from the HRRR, wind fields are robust which supports some high winds.

 

[chrisbray]

Surface dews are creeping up to 60, but moisture above the surface is bad, per 12z ILX sounding. Not a lot to like about it. I will probably still make a run towards the IL/IN border by danville but i don't have high hopes

 

[Tim Paitz]

Heard quite a bit of thunder earlier as they were developing. It rained for less than half an hour but there was no thunder until after they moved out of the area.

 

[chrisbray]

Just got back, and boy, that was a mess. 16z ILX sounding was pretty decent actually, but for whatever reason, maybe it was the massive forcing from the jet streak, it was mostly non-severe and linear. I was on the storm near Tuscola, IL that had a wall cloud early in it's life, but never got much more organized than that. I followed it east into Indiana around i-74, but it fell apart. A few now storms popped up just south of it, but they didn't seem to organize well at all.

End of the day, very little lightning, no hail or wind. I thought it would be a bust, but I also thought it wouldn't be THAT bad