Don’t look now, snow hounds, but there is the potential for a light mid-week snow.
Yeah, I know, I know. Same ol’ song and dance, right?
Well, the reason I mention it this time is that this time, we’re actually within four days and the models are showing some snow accumulation.
Here’s the problem: This is a relatively weak system, with only small amounts of quantitative precipitation (QPF) to work with. The 12z run of the GFS this afternoon, for example, shows around a quarter inch of QPF. That’s enough for more than two inches of snow at the standard 10:1 ratio, but this doesn’t look like a significant snowstorm by any stretch of the imagination.
There’s also another problem: warm air advection. After very cold temperatures Monday and Tuesday, it looks like we will get above freezing on Wednesday afternoon, even here on the northern Cumberland Plateau. The ground temps will be quite cold after the arctic blast that’s headed our way tomorrow (we probably won’t get out of the 20s on Monday and single digits are likely for Tuesday morning), but as the surface temperature warms to above freezing on Wednesday, that could limit accumulation from any snow that does fall — and, as already mentioned, there probably won’t be much snow to work with. Also, if the warm air advection is deep enough, snow could change to rain. The GFS does reflect this potential.
With those thermals in play, timing will be key for this system. If it moves in Tuesday night, when the warm air advection won’t be aided by the diurnal affect, chances for an all-snow event go up. If it moves in during the afternoon Wednesday, those chances go down. One thing to keep an eye on is the model trend with the temps. Output statistics from the 12z GFS top us out at only 33 degrees Wednesday afternoon; this model has been trending colder. However, the GFS is just one model. Other models — most notably, the ECMWF — are somewhat warmer than the GFS.
A verbatim take-away from the GFS model is for light snow accumulations. Crunching the numbers, the COBB algorithm shows 2.1 inches of snow on the 12z run of the model this afternoon; the 6z run earlier this morning showed closer to 1 inch. But, again, this is a single model. Other models show less snow potential at the present time.
Bottom line? This isn’t going to be a major snow by any means. So don’t expect winter storm watches to be hoisted across the state early next week. But it could be enough for close schools for a day or two, and that’s what y’all are wanting anyway, right? On the other hand, it might not snow at all. You know how fickle the weather is around here. At the very least, it’s something to keep an eye on if you like snow, and there hasn’t been much of that so far this winter.
The warming trend is likely to continue into the latter part of the week as a more powerful storm system moves in towards next weekend to bring more rain to the region.
Further out: As we move into the day 8-14 period, it looks like the pattern is going to relax. Models have been fairly consistent in bringing milder temperatures to the region as we close out January. Today’s 12z GFS actually takes temps into the 60s for the first couple of days of February. However, this isn’t a bad thing if you like snow. This pattern has certainly delivered colder temperatures than what we saw in December, but it hasn’t produced much in the way of snow. A reshuffling of the deck isn’t a bad thing. After the pattern reset, there are some long-range signals that indicate Ol’ Man Winter could flex his muscles again in February. And February is often when the bulk of cold and snow fall in East Tennessee during El Nino winters.