Tornado Central

I'm always fascinated to see moderate convection when surface temperatures are below freezing. A look at the Spencer, OK, mesonet meteogram (Spencer is just northeast of OKC), shows that it picked up 0.5" of rainfall in a 20 minutes time span near 1am. The temperature at the time was around 30F, and the temp has continue to fall to a current value of 28F. Not surprisingly, the anemometer appears to have been frozen, given that it's currently not reporting any winds. For ASOS/AWOS and mesonet sites, calm or missing winds are usually good ways to find where the precip has been falling as freezing rain (assuming ambient/environmental winds are >3 mph). A glance at surface obs on the OK mesonet show about half a dozen sites with missing winds (at a time when most wind obs in central and northern OK are 10-15 mph sustained).

FWIW, temperatures have also fallen into the teens in far northwestern OK, with 8-15 mph NNW winds likely continuing to bring in low-mid 20F temps closer to I40. These very shallow arctic fronts have a tendency to be underforecast by most models (both in intensity and speed), so this isn't too surprising.

07 UTC SPC/RUC mesoanalysis also continues to indicate >500 j/kg MUCAPE, supportive of a continued risk of thunderstorms and upright convection. The band of heaviest precip just N of I44 east of I35 in northeastern OK appears to be in an area of decent frontogenetical forcing (and the fun ageostrophic accelerations associated with such forcing). The 850mb cold front may be a good marker for the freezing rain - snow transition zone (or liquid - frozen transition zone).

The VWP from KTLX valid 0720 UTC suggests that the top of the cold layer is ~1800 ft AGL (I'm using the 2.5 degree base velocity data to pick that out easily; KINX / Tulsa / data suggests a similar depth). The cold air deepens to >3000 ft above the KVNX radar, pretty much in line with velocity data from KICT. Given this, I wouldn't be surprised to see some sleet mix in with the freezing rain closer to the OK/KS border west of I35. Well, maybe not, but perhaps close... Same mesoanalysis shows the 850mb front located near a line from Shamrock TX to Emporia KS to the NE MO / SE IA border area.

EDIT: It's important to note that, per OK Mesonet (see HERE), current 2-in and 4-in bare soil temperatures are in the mid 30s in most of northern OK. As such, the precip is not likely to freeze upon impact of roads. Elevated surfaces that tend to cool to ambient temperature more quickly (e.g. powerlines, trees, bridges) are likely icing up rather rapidly right now N of I44. I imagine that it may take until tomorrow night for most areas to see ground temperatures (at least 2" or 4" below bare soil) reach the freezing mark.

EDIT 2: OGE System watch (HERE) is showing >1000 customers w/o power in eastern OKC. Of course, in the scope of things, this isn't a large number. However, I think this is only a hint of what's likely to occur in N of Tulsa through the morning. Latest TLX data shows convection and showers are redeveloping in the quasi-stationary zone along I44, from near Chickashaw to Norman to Stroud and Bristow. My house in Arcadia is currently between this band to the south and the intermittent activity nearer Perry and Guthrie. *shrug*