I am totally baffled on tomorrows forecast. I haven't really be watching this closely with the models and I've only spent a couple hours working on it today, but man this is a tough one. I'd hate to be putting out a forecast for the general public because unless the GFS is totally out to lunch, this one has flop potential written all over it. I did attempt to do some forecasting, but I've pretty much given up on it now. I'll let the guys that are smarter than I am figure this one out and I'll just follow what they say.
I'm just going to copy and paste the post from my blog. I put a map up there too if you're interested in seeing it here is the link
http://loadedgunchasing.com/blog1/
Above is a map of the GFS solution for tomorow, which is very different from what the NAM is showing.
There is major disagreement regarding critical details with tomorrows setup between the NAM and GFS. I have no idea which one to believe. I hope the GFS verifies because it looks pretty good. The NAM isn’t so good. I haven’t been paying close attention to this setup so I’m in the dark on model performance over the last several days. SPC seems to be going with the NAM, but that is just a guess. If they were taking the GFS seriously I think they would be mentioning some tornado potential.
This is a very complicated forecast and I haven’t been spending as much time working on this as I usually do, so take it with a huge grain of salt. I focused primarily on the GFS and made my map based on that. I also tried to figure out the root cause of some of the differences between the GFS and NAM. I’ve only been working on this for an hour or two and solving the discrepencies between the two models is way over my head, but the primary difference effecting the tornado potential tomorrow seems to have a lot to do with overnight convection. The GFS breaks out a cluster of thunderstorms tonight over west central kansas, that tracks off to the northeast and along the KS/NE border through the day tomorrow. The NAM does not show this convection.
With the GFS the overnight convection along the border reinforces the frontal boundary and strongly backs surface winds over the southeastern portion of Nebraska. It also serves to keep surface temperatures down so that the temperature dewpoint spreads are low enough for a good tornado threat. The NAM doesn’t have this outflow reinforcement and doesn’t back surface winds and has much higher temperature/dewpoint spreads as a result, killing the tornado potential.
Further complicating the forecast is the fact that there is no real upper level support. There are only minor disturbacnes moving through largely zonal flow. There are differenes between the two models regarding the finer details of the mid level flow/disturbances as well. Both models do show around 40kts at 500mb over the target area tomorrow afternoon though and when combined with strong to extreme instability that should be adequate for supercells.
I have absolutely no idea what to expect tomorrow. With one model you have >300 0-1km SRH along the boundary in SE Nebraska and with the other one you have about 100m2s2. There is just way too big of a spread with these sorts of details and the surface pattern to know what is going to happen. The picture may become a little more clear later tonight when we see what overnight convection is doing. The latest run of the RUC does not show convection developing over west central Kansas like the GFS does, but the latest run of the RUC only goes out to the forecast hour before the GFS develops convection (the RUC also sucks something fierce at predicting convection).
Due to all the uncertainty and the minimal time I’ve spent working on this I’m going to have to lean on SPC a lot more than I usually would. Whether or not I chase tomorrow will totally depend on what they are saying and on whether or not the GFS looks like it is verifying. If the GFS looks like its verifying I will be on that like a duck on a june bug, but if the NAM looks like its verifying I will sit this one out.
I will update routinely between now and tomorrow afternoon as I get a better handle on the forecast.