Update to Forecast for 5/13

I’m sticking to my guns for the Wednesday forecast. Once again I just kind of glanced over data as I watched TV rather than really locking in and forecasting. My forecasting effort is almost always proportional to what I feel the tornado threat is. I still think this is a lower to mid level tornado threat. Nothing major, but I think we could see a couple decent tornadoes on Wednesday. The NAM finally started to make me a little nervous with this morning’s 12Z run when it did the opposite of what I thought it would and trended back south with the triple point and better quality moisture. The NAM seems to have come back to its senses with the 00Z run and has trended back north again with the triple point in SW Kansas. I’m sticking with the my initial starting target somewhere in the area between Woodward, OK and Minneola, KS. The NAM has storms trying to fire right there near the triple point/dryline bulge in the Oklahoma panhandle, but it dies out quickly. The NAM has consistently shown a narrow warm sector with a waving warm front running east of there. Meanwhile the GFS has stuck to its guns and has a more traditional wide warm sector and more aggressive moisture return into the plains with a plume of good moisture running all the way up through Kansas by Wednesday afternoon. Again I barely glanced at data tonight so take this with a grain of salt, but the driver of the difference between the two on moisture return (which is very important with this setup) seems to stem from convection that will form tonight in the western plains and track through Oklahoma tomorrow. How expansive that is and how disruptive it is to low level flow and the onset of moisture into the central plains will probably start to indicate which models is closer to the truth. Going off past experience and the trends between the two models, my guess is still the NAM is closer to right, but it’s still been overdoing the disruption of moisture return and keeping the triple point/bulge too far south on most runs.

I’ll have to take a closer look tomorrow at the warm front in south central Kansas. I try not to get wrapped up in composite indices, but I definitely look at them regularly. Supercell composite is always a quick easy way to check 850-500 crossover and get a feel for shear profiles across an area. Being a directional shear junkie, that’s always something I’m keeping a close eye on. It’s hard to miss the NAM continuously spiking composite indices along the warm front. Not a big shock. That’s pretty normal to have a spike there with backing surface winds and moisture pooling with any setup. The warm front in south central Kansas doesn’t look like the type of place where a surface based storm would initiate, but there is a chance for morning convection in that area to potentially lay down an outflow boundary and locally reinforce/sharpen the front later in the afternoon, so it’s something to keep an eye on when I do my detailed forecasting tomorrow. Tomorrow’s 00Z run when the HRRR will pick up on this will be real interesting too. As I mentioned yesterday, it seems like the NAM has underdone precipitation with every setup this year. None of the models have done very well I don’t think, but the HRRR has been the closest to right most of the time so I’m real curious to see if it has any storms coming off the dryline bulge/triple point in NW Oklahoma and SW Kansas. Hopefully it doesn’t have some of the BS disruptions at the surface that the NAM does which could limit the instability axis for storms in that area too. It would make me feel a lot better about this setup. Either way I’ll be fine. I’m planning on taking off around noon or 1 on Wednesday and I’ll head towards that Minneola to Woodward area. If I need to drop south along the dryline, I have no problem doing that. I really don’t want to play south of I40 though. That’s kind of my cut off for this one. I’ll be at my target area early enough to make adjustments if need be so these detailed forecast questions are really a nonissue this far out.

So I guess in summary, still a lot of concerns and potential problems with this setup if moisture return into the central plains is disrupted too much. That picture should become much more clear during the day tomorrow. Then I still think the best tornado potential is going to be near the triple point where low level shear is stronger, but in order for that potential to be realized we need some decent width to the instability axis ahead of the dryline bulge, which is a bit of a question mark with the NAM’s output. There are problems, but it’s also May. This is the time of year when things that usually go wrong to mess setups up start to go right. Enough rambling, I’m keeping an eye on it and I’ll get back on it tomorrow.

This entry was posted in Uncategorized. Bookmark the permalink.