A cold start to January has given way to a milder pattern with pleasant temperatures in recent days, but Ol’ Man Winter is prepared to flex his muscles once again in the days ahead.
There are two chances for light snow shaping up over the next seven days. Neither looks like anything to write home about, but some very minor accumulations are possible.
Wednesday night: Colder air will filter into the region late Wednesday, resulting in a rain-to-snow scenario for East Tennessee. Moisture will be limited, particularly after snow-supporting temperatures are in place, and the best chances for light accumulations will be in upper East Tennessee, as has been the theme throughout this winter. Here on the northern Cumberland Plateau, accumulation potential should be limited to a dusting or so, perhaps up to half an inch. Given warm ground temperatures, widespread travel issues aren’t currently a concern.
The National Weather Service’s Morristown weather forecast office published a Hazardous Weather Outlook Tuesday morning noting that snowfall will be possible Wednesday night and Thursday morning “across the higher elevation mountains of East Tennessee and southwest Virginia.” The HWO was vague except to say that “A few inches of snow will be possible above 3,000 feet.”
It is perhaps worth noting that the GFS model is painting several inches of accumulation across the entire northern plateau and Upper Cumberland region. However, it’s also worth noting that the GFS is an outlier. All of the other major models — including the ECMWF, the NAM and the HRRR — are showing generally less than an inch of snow for the northern plateau.
Temperatures will drop into the low to mid 20s on Thursday morning, so some isolated slick spots are certainly possible, particularly on bridges and overpasses.
Monday: A more sustained shot of cold air will invade the region by the end of the weekend, as a low pressure system over the upper Midwest drags a cold front into the Southeast. The trough that develops will keep the eastern U.S. under a northwest flow regime for a few days, which will result in colder-than-average temperatures for at least the first half of next week.
With that, there is the potential for some light snow on Monday and perhaps even continuing into Tuesday. This is what meteorologists refer to as a “northwest flow snow event,” and the northern plateau region typically can squeeze out minor accumulations in these scenarios even when it isn’t snowing in valley locations like Knoxville and Oak Ridge. The terrain differential of the plateau helps squeeze these snow showers out of the cold air advection. Typically, these snow showers feature low moisture content (what the old-timers referred to as a “dry snow” that doesn’t stick to trees and other surfaces and isn’t ideal for snowmen or snowball fights but piles up more easily on the ground). These events are typically light snow-makers, featuring only an inch or two of accumulation under the best of conditions.
Right now, the GFS model is showing a couple of inches of snowfall on Monday. But, again, the GFS is an outlier. The ECMWF model is showing less accumulation. For now, the NWS isn’t really mentioning the potential in its forecast except to say that snow showers are possible on Monday. But it’s worth keeping an eye on.
High temperatures may struggle to get above freezing on both Monday and Tuesday of next week before a warming trend begins on Wednesday, ahead of the next storm system.
Further out: There’s still no sign for impressive snow or a legitimate winter storm threat as we move into the first half of February. However, there are some long-range indications that a colder and potentially snowier pattern could be setting up for the middle of February. If you’re hoping for snow — not a few nuisance snow showers or flurries, but real snow — that may be your last-gasp hope before winter begins to give way to spring. Monday’s mild temperatures and thunderstorms were perhaps a foreshadowing of what’s in store. Thunderstorms aren’t unheard of in January, but they aren’t terribly common, either. There are some indications, though, that this upcoming spring season could be particularly active in terms of severe weather.