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Groundhog Day arrives next week, when by tradition we let a rodent help us reassess the state of the current winter.
But for many in Southwest and Southside Virginia, when it comes to this winter’s weather, it might already feel more like the Bill Murray movie “Groundhog Day” in which a day keeps repeating over and over again.
We get marginal, patchy ice, usually somewhere up high or out in the western or northern edge of our region, then cold rain. That’s been Dec. 14, Dec. 22, Jan. 8, and this past Sunday (very weakly, most of the moisture dried up) and on this Wednesday. It’s often followed by windy cold, a short warmup, then rinse and repeat.
Storm systems keep cutting west of our region rather than tracking south of us and up the East Coast, the optimum track for widespread snow that some are desperately yearning for and others are hoping we can run the 2022-23 table without.
The reason for this repeated pattern is a persistent ridge of high pressure over the southeast U.S., which is a common feature of a La Niña -influenced global atmospheric circulation.
La Niña refers to the irregularly recurring cooling of a stripe of equatorial Pacific waters, with historic linkage to certain weather patterns in various parts of the world. In our region, it usually, but not always, results in a milder, drier winter (this one isn’t that dry), resulting from that ridge of high pressure parking over or just offshore from the southeast U.S.
Back in early November, this column posited that the much-ballyhooed third-year sequel of La Niña and the mild winter expectations it generally brings might not entirely define the cold season ahead.
The idea that there were signs in fall that seemed to point to a colder winter seemed to hold sway early, but all that played itself out by Christmas. We certainly got the cold blast, but not snow.
Since then, it has been a pretty classic La Niña pattern for our part of the world, featuring the southeast U.S. ridge.
The ridge of high pressure keeps storm systems and cold air masses from digging too far to the south and east. That’s why the West and the northern Plains have been getting tons of snow and we’ve had very little, virtually none for many locations outside the mountainous areas of far southwest Virginia and the West Virginia border area that have had a couple rounds of upslope snow showers.
La Niña has been with us for three winters in a row now, and even though the last two have had a few more episodes of widespread snow and ice than this one has so far, the southeast U.S. ridge’s presence has been felt the previous two winters in deflecting away major Arctic air masses and pushing many storm systems off of optimum winter storm tracks.
This is only the third time in the modern era of sea surface temperature data, dating to 1950, that we’ve had a third winter in a row with La Nina. Both of those other winters, 1975-76 and 2000-01, were meager for snowfall in our region, also.
But there are some ways to get a winter storm in a pattern with such a persistent southeast ridge.
One is to have cold air pressed ahead of the storm systems tracking to our west forcefully enough to hold there while the moisture and warmth are lifted over it.
We discussed this last week in a column about cold-air damming. It doesn’t necessarily take a full-on cold-air damming pattern to get enough cold air wedged against the mountains sufficiently for moisture to overrun it for wintry precipitation. It just really hasn’t happened to a great degree yet.
High pressure placements in southern Canada could allow this to develop with some of the storm systems ahead, but it all comes down to nitty-gritty details with the atmospheric setup in each individual situation. These usually turn into wintry mix events – or maybe wet snow changing to wintry mix – rather than pure snowfall.
Yet another way is to have a cold air mass descend southward with such breadth and intensity to dislodge the southeast ridge, as the atmospheric furniture rearranges.
And that’s where we get to Groundhog Day.
About that time, the middle of next week, a potent Arctic air mass will be oozing southward from Canada into the central U.S.
This will be the most intense Arctic air we’ve seen enter the contiguous 48 states since the Christmas blast that dropped us near zero or below with those bitter 50-plus mph wind gusts that knocked out the power for thousands.
It is very doubtful at this point that this new Arctic air mass will arrive here with as much gusto or intensity as that one.
In fact, it’s at least a little doubtful it will get here at all, at least in anything resembling its original chill in the Northern Plains.
But the Arctic air mass may be just enough to body up to the southeast U.S. ridge, shove it aside at least a little bit, and perhaps create a window around Groundhog Day and the days after for southerly storm systems bearing moisture to encounter cold air without being bounced too far west.
Maybe.
What happens from there with the weather pattern is the subject of even more conjecture. Most expert bets would be on the ridge building back and resuming our mild winter after a temporary bout of cold and, maybe, some short-lived scrape with snow and ice.
But there is at least some school of thought that, with La Niña actually weakening and likely to fizzle out altogether in a few weeks, the cold push of air might gain some traction and re-work the weather pattern into something more winterlike for our region, and adjacent parts of the East and South, for much of February.
For snow fans and winter haters alike in our region, there appears to be a lot riding on the next couple of weeks.
I said once before that I never entertain the possibility of having an essentially snowless winter until at least Valentine’s Day. But we may be able to rat out by Groundhog Day whether winter is really going to happen or not, regardless of whether the furry forecaster sees a shadow or not.
ROANOKE’s WARMEST FIRST THREE WEEKS OF JANUARY ON RECORD
What if I told you that last winter up to Jan. 21 – when much of the region was covered by several inches of snow-sleet crust – was even warmer than it’s been this winter to that same date with very little snow so far?
That’s a strange but true point we’ll get back to, after acknowledging a historic run of winter warmth for the region’s largest city.
For Roanoke, it was the warmest first 21 days of January on record, averaging 46 degrees. January 1950 had the second warmest first three weeks, at 45.7 degrees, and ended up as Roanoke’s warmest January on record, going back to 1912, at 47.5 degrees. The remaining days of the month don’t appear as if they will be warm enough for this January to become Roanoke’s warmest on record, but it will likely remain among the top few.
By comparison, the first three weeks of last January, with two snowfalls totaling 10 inches in the Star City, averaged 11.5 degrees colder than those same weeks did this January.
However, in what may seem a bit of a mind-blowing twist, meteorological winter to date – December 1 to January 21 – was actually warmer last year than this go-round, 43.4 degrees to 41.6 degrees, at Roanoke.
That’s because of the vast difference in Decembers – nearly 10 degrees difference in average temperature, between 48.2 degrees in December 2021 (second warmest on record, trailing only 49.9 in 2015) and 38.6 in the December just past. Despite the extreme Christmas weekend cold blast, that ranks as only the 44th coldest December, fairly average historically for a December.
So it’s true, last winter was warmer in Roanoke through January 21 than this one has been, despite being much snowier, but this January through its 21st day was the warmest it’s ever been in over 110 years of recorded weather data.
Elsewhere in the region, the first 21 days of January were the sixth warmest on record at Danville (going back to 1918, missing nine years with more than 3 missing days in January) with a 46.3-degree average; eighth warmest on record (going back to 1893, with four years excluded for missing days) at Blacksburg with a 41-degree average; and ninth warmest on record (going back to 1893) at Lynchburg with a 44.8-degree average.
Once we get to the end of this winter and see where it finally falls with regard to temperature and snowfall, we can more accurately analyze where this season stacks up historically for our region and how that fits in with broader climate trends.
For now, we have many miles before we sleep on winter, whether or not the woods fill up with snow.
Journalist Kevin Myatt has been writing about weather for 19 years. His weekly column is sponsored by Oakey’s, a family-run, locally-owned funeral home with locations throughout the Roanoke Valley.