I'm taking a moderately optimistic view of the situation I guess. It's been known that the two primary negatives for the event are the meager moisture availability and the less-than-ideal timing of the arrival of the primary vort max to the west. Regarding the first negative -- it's February, that's all I'll say. I don't recall too many February days in the past 5-6 years that featured >60F dewpoints in Oklahoma. When 500mb temperatures are as cold as they will be, I'm not AS concerned about mid-upper 50 dewpoints as I would be otherwise. Of course, temps in the 70s with Tds in the mid-upper 50s still leave relatively high (or at least not ideal) LCL heights. But hey, we've had a hard enough time getting 60 degree Tds by the end of March the past couple of years, so I'll take it.
The timing of the approach of the vort max is still an issue, obviously. The latest 00z NAM indicates the leading edge of the vort max (or basically the area of DPVA) moving into the central TX panhandle by 00z Sat (Friday evening). With sunset around 0030z, this creates an obvious issue. Without a whole lot of mid-level upward motion, we'll have to depend more strongly on low-level convergence (though we usually need some low-level convergence any) to initiate convection. Wind profiles will be moderately strong by 00z, with 50-60kt 0-6km shear oriented perpendicular to the dryline, a fact that should promote discrete initiation initially. Now, I would be quite happy if this arrived 6+ hours earlier, but I'm not sure that is going to happen. As it stands now, the 00z NAM doesn't initiate precip in the target area until 3z-6z (in southwestern OK). As others have noticed, however, model convective initiation (and convective parameters) can be suspect at times, so I'm still holding out hope. Regardless, the bulk of the forcing won't really approach the dryline until near and after 6z. Looking at the deep-layer shear vector forecasts, a squall line looks very likely after 6-12z, as backing and strengthening 500mb flow acts to back the 0-6km shear vector such that it is nearly parallel to the dryline.
[EDIT: Looking at the 0z NAM, it certainly looks to me like the midlevel trough will move out more slowly onto the plains. This does not bode well for Friday activity... I really should address the GFS more in this thread, since I'm not a big fan of the NAM. The 00z GFS remains quite consistent with the 12z run in the positioning of the cyclone and trough by Friday evening. I've generally been more pleased by the GFS than the NAM in the past 9 months, but that's another topic (and entirely anecdotal).]
I am intrigued by the potential for tornadic supercells across portions of Texas and Oklahoma overnight Friday and into Saturday morning. Intense cyclogenesis associated with the approach of the strong upper-level trough will result in a substantial ageostrophic response. With an increasing pressure gradient, I suspect that the low-levels will remain relatively well-mixed through the night (at least through 6z), which could allow supercells to become surface-based or remain surface-based through midnight. With the low-level RH being not particularly high, radiational cooling may lead to some decoupling, but, in my experience, setups such as this tend to allow for surface-based convection later into the night than is typically observed.
One of the more unfortunate aspects of this event is the fact that the developing trough won't be well-sampled by the RAOB network until Friday morning (the time at which the trough deepens and moves inland), though the downstream environment (relative to the trough axis) may be sampled by some of the sounding sites along the Pacific coast Thursday evening. Of course, there are still thousands of satellite observations (in addition to aircraft obs, etc) that are being used to initialize the models, but it's almost always good to get sounding data.
Whew. I agree that there are plenty of negatives. But, it's February, and I haven't chased since late November (and haven't had a "good" chase since September). I'd much rather be agonizing over this setup than looking at a huge east coast trough, that's for sure (though, there IS a big trough/low moving off the east coast). I have all plans to chase Friday, but my expectations are low.
If those areas were closer I'd go for it!
