I have looked over the 12Z data and there are some differences between the two, but I’m not going to point out every difference between each one because it’s a pain in the ass and doesn’t tell you anything anyway. I agree more with the GFS on some things and I agree more with the NAM on others. I still haven’t checked the European or UKMET.

My forecast focuses on the dryline area over the northern half of Oklahoma and the southern half of Kansas since this is the area that I plan on chasing (I think this area and the surface low have the highest tornado potential).
Monday morning a dryline should be located over western Kansas and extend south into the Texas panhandle. The dryline will mix east through the day and should be in the the vicinity of Woodward by late afternoon when storms fire (dryline location could change).
The big problem with this setup is moisture and instability, as it traditionally is this time of year. I honestly don’t know what to think about dewpoints and instability. Both models have been pointing towards 55 degree dewpoints or so near the Kansas border by Monday afternoon. Surface temperatures over this same area have changed drastically from one run to the next over the last couple days, so there is a lot of uncertainty regarding that too (which influences instability). Both models are showing around 1000j/kg of CAPE ahead of the dryline. That is far from good, but it is certainly OK for this time of year. My thinking is that cloud cover will begin to clear/break up over Oklahoma Monday morning and spread northward into Kansas allowing decent insolation in a 60 mile wide area (at least) ahead of the dryline. This will create your typical spring time thermal tounge that covers the dry sector and overlaps into the warm sector.
Moisture advection is much more difficult to predict. Soundings along the gulf show very shallow moisture currently. There are favorable trajectories in the low layers of the atmosphere from now until Monday afternoon for moisture transport to the target area and there are dewpoints in the 60′s over the gulf, but the models want to mix down the moisture as soon as it moves on shore in Texas and then the dewpoints are more like 50 degrees. By Monday both models show mid 50 dewpoints over the target area and possibly high 50′s. I don’t know much about vertical mixing and its effects on moisture so I’ll have to believe the models for the most part on this one. If dewpoints only get up to 55 near the KS border, that isn’t very good and the tornado potential will be very low. If we can get dewpoints into the upper 50′s near the KS border then I think we’ll have a solid 5% tornado probability over the dryline area centered on the border.
The good news with this setup is the shear. A few days ago the directional shear was nonexistant, but it is half way decent now. Deep layer shear is quite good and when combined with 1000j/kg of CAPE will be supportive of supercells. Low level shear is pretty good with both 0-1km and 0-3km SRH exceeding the traditional thresholds for a tornado threat. 0-1km SRH gets as high as 200m2s2 around 00Z, which is quite good (and 0-1km SRH is a better predicter of tornado potential than 0-3km SRH). Forecast soundings show decent hodographs with a little curvature in the lower levels (not as much directional shear as I’d like to see, especially in the 0-3km area) and sufficient length. The low level winds are very strong though and this can help to offset a lack of directional shear. 850mb winds will be screaming by 00Z.
With poor moisture LCL heights are going to be at the higher end of what is acceptable for a decent tornado threat. I haven’t looked at many forecast soundings, but I expect them to be around 1000m AGL.
The GFS and NAM have both been very consistent in breaking out convection all along the dryline with a tail end to the convection in the KS-OK border area. I think this is the best area where you have a good chance of a storm firing early and remaining discrete. Further north storms likely won’t be discrete and farther south storms may fire too late. This is my compromise between the two.
My target is going to be some where between the Woodward area north to the KS border (where ever the dryline is). I think storms firing in this area and tracking northeast towards Medicine Lodge will be in the best environment.
Basically we have a setup with good deep layer shear, moderate directional shear, poor instability, poor moisture and strong low level winds. That is a good mix of good and bads and makes forecasting the tornado potential extremely difficult to say the least. I do think they will get a couple weak tornadoes near the surface low and then I think there is a pretty decent shot of a tornado with any persistent supercell firing along the dryline in the area I’ve discussed as my target (we may not get any persistent supercells though). I think there is a solid 5% tornado probability over my target area and another lower end 5% near the surface low (higher probability along the dryline to account for the potential of stronger tornadoes).
We are still a long ways out and a lot can and probably will change. Check back for updates and additional forecasts. I will be updating regularly (whenever I have something to say) and I will be posting forecasts at least once or twice a day.
Below is a map with a striped box to indicate the general area I think has the best tornado threat.