I just updated my blog so I will just copy and paste that here instead of writing it all out again...
The GFS continues to show an extraordinary setup for next Monday. The million dollar question is whether or not if will verify. I’ve seen a lot of really good setups go to absolute crap inside of 72 hours, so I am being cautious about fully buying into some of the paramaters being forecast for Monday. It is tough not to get excited though because this is the best setup I’ve seen for the plains since 2008.
The GFS and ECMWF are in pretty good agreement with the timing and overall intensity of the trough that should eject into the plains on Monday. They have been pretty consistent with each other and to a lesser degree the timing over the last several runs. They have had some significant differences on how to handle the evolution of the upper air pattern, with the GFS flopping back and forth from a one large trough to a two smaller waves solution, but that hasn’t really had any impact on Monday’s setup (it has to do with any potential chases beyond Monday). So while there have been some differences, the models seem to be doing a good job with Mondays forecast.
I think everybody is starting to pick up on the fact that Monday is looking exceptionally good. The paramaters are great all across the board. If the models were breaking out precip along the dryline and LCL’s could lower by about 200m, this would literally be as close to a perfect setup as you’re going to get. There is a lot that can change between now and then though. I haven’t seen any reason to doubt the model forecast for Monday yet, but just going off past results you know its a little dangerous to buy into details this far out.
Again in this mornings run the GFS places a surface low over southwest Kansas (north of its placement in yesterdays run) with a dryline running south from there across western Oklahoma. Dewpoints are being forecast in the low 60’s across the warm sector. I think us getting dewpoints >60 along the dryline is highly likely, so moisture is of no concern for me with this setup. It would be nice to get dewpoints up to about 65 to help bring the LCL heights down a tad, but they are plenty good enough right now to support a strong tornado threat on Monday.
Surface temps are in the low 80’s ahead of the dryline which brings CAPE up into the 3000J/kg range, which is pretty damn good for this time of year. Deep layer shear and the CAPE being forecast will create an environment extremely favorable for supercells. The shear vectors are normal to the boundary, so discrete supercells will be the mode of convection.
It is still too far out to consider the specifics affecting tornado potential with this setup, but I’ll go over some of them just because they are so impressive.
0-1km SRH is forecast to be >400m2/s2 along the dryline with >600 closer to the triple point. To put that in perspective you usually look for >100 for a solid tornado threat. We cover that four times over with this setup. With good directional shear and almost 50kts at 850mb the shear profile will be very favorable for strong to violent tornadoes.
The GFS shows 1km EHI at 8 over the warm sector and a significant tornado probability of 15.9. Those are off last nights run because they haven’t updated yet, but those numbers won’t drop with the 12Z run.
The hodograph for Monday will be amazing if this holds together. Once you get off the dryline into the warm sector surface winds are out of the southeast at around 20kts. 850mb winds are out of the south at 45kts. 700mb winds are out of the southwest at 55kts. And 500mb winds are out of the WSW around 60kts. The best hodograph I remember ever seeing was the NAM forecast sounding from the night before the Greensburg tornado and this one would give it a run for its money if it verified.
When you consider everything the GFS is showing this setup looks great for cyclic tornadic supercells capable of strong/violent long-track tornadoes. It is easily the best setup I’ve seen for the plains since May of 2008. It is important not to get too comfortable with what the models are showing this far out though. For our last setup the GFS was overdoing wind speeds by about 20kts at 850mb. 20kts makes a huge difference in a setup like this. That being said I am extremely optimistic, but I’m not signing off on this yet. If it verifies though and the cap can break, it would be a major tornado outbreak.
My biggest concern by far with what the GFS is showing is the cap. At 00Z there is still a fairly significant cap in place and none of the model runs have shown precip breaking out. Now with the earlier model runs a couple days ago when it was showing the trough just barely nosing into the plains on Monday I could see a cap bust happening. I don’t think that is a very probable outcome in this situation since you have upper level support and a rapidly deepening surface low. Even though that is the case any time the models aren’t showing convection it should be a cause for concern.
This is an extraordinarily good setup for tornadoes. I am extremely pumped to see the potential for violent tornadoes with the models because it is a very rare thing. Like I mentioned earlier I haven’t thought a setup was capable of violent tornadoes since the Greensburg outbreak. There is still a lot that can go wrong with this though so I’m keeping my hopes in check for now. I will continue to watch this very closely and I will probably update my blog a couple more times today after I have a chance to go over more details.
