2013-05-15 FCST: TX/OK/KS

[brice.coffer]

I have been intrigued with GFS forecasts for Wednesday D4 for a few days now. I see potential in the SW OK/NW TX region. I'll start with a negative aspect though. The upper-level cutoff low over the Baja peninsula ejects northeastward over northern Mexico and into TX/OK without much response at the surface. By the time the broad surface pressure trough develops into a surface low near LBB, the upper-level disturbance has overrun its lower-level counterpart, giving the system a distinct eastward tilt with height. Not an ideal synoptic setup from a QG or PV point-of-view. However, the GFS has been remarkably consistent for the last several days with a northwesterly flow setup. The 180 degree SFC-500mb crossover is also worrisome, but that is usually the case with NW flow. The basic parameters are in place, and considering the season so far, its a day worth keeping an eye on. I just started looking over the 84hr forecast from the NAM, and the severe potential seems lower in that model solution. I'll hopefully post more in the coming days.

SFC PRS/PRECIP:

2M THETAE/SFC WNDS

MUCAPE/6KM BULK SHEAR

 

[Jeff Duda]

Wow, this is messed up. The NAM and GFS both show a departing shortwave. Usually that means you will have northerly surface winds as a surface ridge would be approaching the area from the west or north. Here, we have the exact opposite happening somehow. It's that eastward tilt you mentioned, and I don't think I've ever seen that before. One problem with that is that you have both AVA and CAA into the region (mostly OK) as the temps are actually cooler to the southeast in TX/LA, perhaps owing to persistent cloud cover or rain in the lee of the trough. So those are two factors hampering things. Also, I see better instability north of what would usually be the warm front . In this case, it seems to be acting more like a northerly moving cold front.

I guess all in all, the ingredients are there (marginally), so if a storm would manage to go up along the dryline or pseudo-warm-cold front and continue moving south, it could have some instability and shear to work with. Also interesting is the wind profile. If a storm manages to turn in a typical fashion, the storm motion would be a nearly zero vector. A right mover might even move west!

Will have to keep an eye on this, but my guess is this will end up being mostly a non-severe weather event.