Plans are in their final stages for tomorrow's marathon chase. As of now, I have Jon V, Allison, and Tom coming along with me. I've talked to everyone and we're all a go as of now.
There are two areas to watch for tomorrow. The first is the better of the two up north. The second is along a dryline which is forecasted to setup from north to south in Eastern Nebraska, Eastern Kansas, and southward into Oklahoma.
The northern target is my initial play. With a departure out of Brighton at 6:00am, we could feasbly make Sioux City, IA by 3pm CDT. If storms haven't fired yet, we could find ourselves in decent position. Better dynamics and shear rest up there. The front is in the vicinity, and will need to remain behind us, otherwise we'll be sitting in a fast moving squall line with little hope. This area is also closer to the low which will keep surface winds coming out of a favorable direction. The WRF at 0z Sun has 80 and 90kts of winds screaming out of the SW over Central Nebraska into NW Iowa and Southern Minnesota. Better difluence is just south of this over Eastern Nebraska, Southern Iowa, and Northeast Kansas. The 250mb jet max is centered over Northern Nebraska and Southeast South Dakota, so the area of concern sits in the right entrance quad of this jet. Closer to the surface, the WRF is hinting at TDs near 70 which I think is way overdone. Currently, TDs are in the 50s with 60s over Southern Kansas and points south. I'm not sure all of that will advect into our target area by tomorrow afternoon. I think mid 60s would be a reach, but definately a safer bet than lower 70s.
On the other hand, the GFS continues to slow this system down. The previous runs had the 500mb low sitting over Central North Dakota at 0z Sunday. The latest runs have it backed even further west in extreme Western North Dakota. This obviously pulls our target area back to the west and closer to home for us. The bulk of the precip being shown on the GFS is sitting in extreme southeastern South Dakota and extreme northeastern Nebraska. However, CAPE values look much better in Southern Nebraska as opposed to the northern areas as the GFS is progging nearly 2500J/kg along the KS/NE border and only 1500J/kg in SE South Dakota.
This is a tough call... you know there's going to be a squall line along the front, which is why areas in Southern Nebraska and Northern Kansas are being eyeballed; while the dynamics are a bit weaker there, the chances for storm isolation look much better, and of course with that, tornado chances also improve a bit. Storm motions are also a concern as models have them progged as high as 40kts. The biggest concern is the time frame heading out; can we be where we need to be in time? We can spend all night running around as we have most of Sunday to get home, but if we're going to drive all day Saturday to fall short, that'll all but kill any reason to go out.
I must admit to liking the GFS's slowing of the system. Even if there's a northly trek in our journey tomorrow, areas west trim off valueable time for us.
With all that said, our plans are to be on the road from Brighton tomorrow morning at 6am and we'll just haul out I-80 towards the Lincoln/Omaha area and make a quick evaluation from there to determine what warrents the next move. The upside to a setup like this is that there will be storms to play in, regardless whether they're lined together or isolated. Add to that cheaper gas prices being split four ways makes for a reasonably cheap trip. I'll probably post a quick update before I leave campus later this afternoon.
