Monday, December 18, 2017 8:17 PM

Wintry Weather Still A Possibility For The Southern Plains

Christopher Nunley

Introduction/discussion:
Wintry precipitation still remains a possibility for parts of the Southern Plains this upcoming Christmas weekend. A strong cold front will move through Oklahoma and Texas on Thursday and Friday. Numerical guidance is struggling with the timing of the cold front, but the faster guidance is likely correct due to the density of the arctic air. This will cause temperatures to plummet just ahead of the weekend. It should be noted, patch drizzle may occur late Thursday night behind the cold front in Oklahoma. With temperatures in the 20s at this point, anything that falls would freeze on contact. This should not be a widespread event, but I will keep a close eye on the situation.

High temperatures will remain in the 30s (see Fig. 1) for most of Oklahoma on Friday, and high temperatures in Texas will likely occur on the morning of Friday before falling into the 30s/40s (outside of far south Texas where a later frontal passage is expected). High temperatures on Saturday will range from the 20s in northwestern Oklahoma to near 50 close to the Texas coast (see Fig. 2)–it is possible the models may be too warm with this arctic airmass, too.

Fig. 1: Friday afternoon temperatures (GFS)

Fig. 2: Saturday afternoon temperatures (GFS)

Light snow possible:
If the airmass behind the Thursday/Friday cold front was not cold enough, a secondary surge of arctic air will advance into Texas and Oklahoma by Saturday into Sunday. A robust shortwave will dive southeastward into the Southern Plains, sending a secondary shot at cold air (see Fig. 3). It is possible light snow will develop along and just behind this cold front as model guidance has been strongly hinting at mid-level frontogenesis.

Fig. 3: Shortwave diving into Texas/Oklahoma Panhandle Sunday morning (GFS)

Precipitation would likely fall in the form of light snow (forecast soundings show a favorable snow profile) Saturday evening into Sunday for Oklahoma and possibly northern Texas (see Fig. 4).

Fig. 4: Forecast sounding Sunday morning (GFS)

It should be noted, I am keeping an eye on southern Texas Christmas morning. Some guidance hints at moisture hanging around this area, with cold surface temperatures and very cold temperatures aloft, so this scenario needs to be watched carefully. I also plan to have an article out later this week discussing the continued cold/active period expected between Christmas and NYE for parts of the south.

Accumulations:
It is too early to accurately forecast accumulations. As of right now, accumulations appear to be light, but enough to possibly lead to a white Christmas for some in Oklahoma and north Texas (since the snow will remain on the ground into Christmas morning). Climatologically, frontogenesis snow events in this region produce between 1-3″ of snowfall where the most intense banding takes place. So, I will go out on a limb and say these are the highest totals likely with this event unless something changes. The most favored areas to see snowfall are in far northern Texas and Oklahoma (see Fig. 5).

Fig.5: Potential snowfall map