When it comes to forecasting a mixed winter precipitation mode in the Southern Plains, we ask only that you give your local weather guy a break this week. I can guarantee you they’re drinking tons of coffee and Red Bull and probably even using their best mystical tricks to gaze into the unknown to try to figure this one out. The potential winter storm this week, January 13-14, is going to be a toughie to figure out as most are in this region.
Its All About that Freezing Line
These types of events hang on one big line in the whole show: the freezing line.
In a situation like this, where you have significant warm air advection going on over the top of a shallow arctic airmass, getting freezing rain seems a certainty in the transition from a cold 33F and 34F rain to a freezing rain of 30-32F.
However, warm air is going to want to be building in, so the actual location the freezing line is at during any given point of an event is going to be hard to discern — and then figuring out the actual amount of glazing of ice you can get before it warms back up above freezing in that transition line and it all melts is also going to be hard (nay impossible) to figure out at this point.
What I can say is that the models above (GFS and NAM) have vastly different ideas about where that freezing line sets up. Currently the GFS has been consistent in keeping it NW and the NAM has been more consistent with putting it over the I-44 corridor. Historically, I’d lean towards the NAM over the GFS on this battle and I tend to now. Throughout the years, chasing/documenting ice storms in the Southern Plains it seems the GFS always has a weird slow to cool bias that gets proven wrong. Probably the case again on some level.
So Let’s Be Real, How Much Ice and For Whom?
Now that I’ve spent some time talking about the why this setup has a lot of uncertainty, let’s talk like things are certain (when they really aren’t).
The NAM shows a band of stronger precip totals over the top of a pretty shallow arctic (in this case just at freezing) airmass:
As of 6pm on Friday, the NAM is showing our temps to be warming and the freezing line retreating north, giving way to the warm air advection a bit I’d assume. The GFS is more aggressive on the warming and has the state going from freezing temps and ice storm in the NW for a bit and 60s and humid in the SE. The Euro (we can’t share it, sorry) is a bit on the cooler side with the NAM but even it warms things up by Saturday.
It certainly appears the prime time for icing will be Friday and Friday Night. At some point Friday Night into Saturday I think that warm air starts winning and we warm to above freezing and perhaps some of us will go from an Ice glaze to 60F and rainy over the course of 24 hours.
There will probably be a narrow corridor of some significant icing somewhere just N and W of where the freezing line sets up — but that icing may not last a long time as the air warms above freezing with continued heavy precipitation (rain in this case) on Saturday.
So in short, there’s a lot of details still to figure out. There will be some icing going on Friday for sure and possibly into Saturday with the freezing line gradually shifting N and W. Heavy rain will continue throughout the weekend with flooding becoming a possibility as well.
We’ll have at least one more blog on the site sometime before Friday. Check back then!