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The book hasn’t closed on the 2023-24 winter. Its defining chapter has yet to be written.
The development of what appears likely to be a near-textbook pattern for surges of cold air and possible winter storms in the eastern half of the U.S. over the last two weeks of February and maybe a week or two into March has the potential to rewrite the script considerably on what has been mostly a mild, rainy winter. At the least, it will provide some windy, chilly speed bumps on the way to what may seem like an early spring already starting this week.
Forecast guidance is in strong consensus on the development of large blocking high pressure over the northern latitudes that will push colder air southward. Add to this high pressure over the western U.S. to help drive the cold air more deeply southward over the central and eastern U.S., plus a potentially enhanced southern branch of the jet stream common during El Niño, the ongoing warming of a stripe Pacific Ocean sea surface temperatures, and the stage could be set for wintry precipitation chances in the next few weeks.
The hopes of many eastern U.S. snow fans, including those in Southwest and Southside Virginia, who have not been satisfied with a strong El Niño winter that has thus far produced barely more than a week of real wintry weather, are being poured into this period of time for a late save of the 2023-24 winter. But there are no guarantees that snowy dreams will be fulfilled.
Meanwhile, those not inclined to snow and cold are rooting for the groundhog to be right about an early spring. While this cold air appears unlikely to be as sharp as that we experienced for a few days in January, it may well have much more persistence with a few rounds of resurgence. The groundhog’s early-spring prediction — for Pennsylvania where he lives and for us — is in serious jeopardy.
Speaking of spring, for those into baseball, you can think of this developing atmospheric pattern as the meat of the order — the third, fourth and fifth batters — coming up to bat for Team Snow.
As any baseball fan knows, having the hitters most likely to get on base or hit home runs actually do so is never a certainty. There can be unknown nagging ailments and mental slumps affecting those batters, not to mention ace pitchers who know how to get sliders, curveballs or fastballs past them. The batters can strike out, ground out or pop a foul even with hard swings and fat pitches. But you figure that if three .300-ish batters are due up with the game on the line, then there’s a good chance at least one gets on base and maybe another will drive that one home.
Similarly, it is possible that this highly potent winter pattern passes with all its storm systems suppressed southward or weakened by converging winds aloft, leaving us mostly dry, or the systems nudge west between Arctic air shots bringing us cold rain. Winter storms could mostly slide around us to the north, south or east and give other regions besides our own snow and ice. Strong upper-air flow out of the Pacific Ocean or a remnant warm high-pressure ridge over the Atlantic could alter the pattern just enough for would-be winter storms to go awry. Any or all of that can happen to individual storm setups relative to our region even if the broader atmospheric pattern is considered highly favorable for winter storms.
But, for somewhere between two and four weeks, it appears there will be an enhanced chance that atmospheric setups capable of bringing snow, ice or wintry mix to our region will develop. The chances for multiple wintry precipitation episodes are higher than typical in this kind of atmospheric pattern. It is within the realm of possibility that we could catch up quickly or at least close the gap substantially on all those snowy winter forecasts that haven’t panned out thus far.
It will be during this time, roughly Valentine’s Day to a week or two into March, that the personality of the 2023-24 winter in our experience and memories will be established, based on how many of these potential winter storm setups come to fruition, and how intensely.
On one end, the timeframe could just pass as a mostly dry period with a few cold, windy shots that leaves the winter as a “one-hit wonder” for significant snow, or even for some in Southside, a near-repeat of the prior virtually snowless winter. On the other end, it could completely redefine this winter as a memorably cold and snowy one, even though most of it hasn’t been.
Something in between those extremes is the most likely — say, a couple of episodes of wintry precipitation amid two or three weeks of generally colder than normal temperatures.
Spring is likely to blossom rapidly on the far side of this colder period, about March 15, give or take a week.
The home run regionwide monster snowstorm that we haven’t had since early December 2018 has a much higher risk of occurring during an atmospheric pattern such as the one that is ahead, though the chances of that actually happening specifically for our region are still somewhere well below a coin flip.
But 10 years ago this month, such a storm happened with none of this same atmospheric furniture in place.
February 2014 snowstorm, 10th anniversary
A decade ago on this date, there was starting to be some buzz about possible snow in five days. But there wasn’t yet much of a clue about how profound the Feb. 12-13, 2014, winter storm would be for many localities in our region.
Depending on where you are in our region, it’s likely that either the December 2009, December 2018 or February 2014 snowstorm is the largest you have experienced thus far in the 21st century. (Some areas in Southside got the most in January 2000 and possibly a few here and there nearer I-64 got the most in January 2016.)
Among the locations where February 2014 rates the biggest snowstorm for the 21st century to date are Christiansburg with 23 inches; Woolwine, 21 inches; Blacksburg, 20.1 inches; Martinsville, 19.8 inches; Willis, 19.6 inches; Roanoke, 19 inches; Copper Hill, 18 inches; Rocky Mount, 16.5 inches; Radford, 16 inches; Pulaski, 15.8 inches; Clintwood, 15.5 inches; New Castle, 15.2 inches; and Saltville, 13 inches. Most of Southwest and Southside Virginia topped 10 inches in the 2014 storm, though some in Southside came in a few inches less.
In some ways, the February 2014 snowstorm was classic, with low pressure along the Gulf Coast spreading moisture northward into trapped cold air, then the low tracking up the East Coast continuing to circulate moisture into it. The surface low was followed by an upper-level low, as is typical, that provided an intense conclusion to the winter storm to some of the locations that got the most. (My location south of Roanoke got 8 additional inches of snow in about three hours on Feb. 13, for 22 inches total.)
In other ways, the February 2014 snowstorm was off the grid. One reason it didn’t seem likely several days prior that such a major winter storm could occur is that the climate oscillations we typically look at for signals of the highest likelihood of wintry weather were in the opposite phases from what is considered prime.
· The North Atlantic Oscillation, which refers to the placement and intensity of pressure centers over the Atlantic Ocean north of the equator, was in a weakly positive phase, with an index ranging around 0.7 to 0.8. This means that pressures were weaker near Greenland and stronger to the south. It is the negative phase, with higher pressure near Greenland, or a blocking high that causes the jet stream to buckle southward behind it over the eastern U.S., that we typically look for in our most wintry periods.
· The Arctic Oscillation, based on air pressure around the North Pole, was in a moderately positive phase with over a 1.0 index, signaling low pressure pulling cold air tighter to the pole, as the storm developed. We generally look for a negative phase — or high pressure over the pole loosening the tropospheric polar vortex and pushing cold air farther southward — in our more wintry periods. The AO did take a steep drop to negative territory shortly after the snowstorm moved up the East Coast before rebounding to positive numbers again a week later.
· The Pacific-North American pattern was in a moderately negative phase, below a -1.0 index, which means a broad low-pressure system was placed over the western U.S., where we’d typically be looking for a high-pressure system, or the positive phase of the PNA, to press cold air southward into the eastern half of the U.S.
Additionally, the equatorial Pacific was in a neutral phase throughout that winter — neither its warm-water El Niño phase nor the cool-water La Niña phase. El Niño has been ongoing during four of the last five snowstorms that dropped a foot or more on half or more of our region. In other words, all of them back to 1998 — except the 2014 snowstorm.
So how did this happen with everything that usually works for large winter storms not present?
First off, the 2013-14 winter was different than many recent winters that have tilted mild, in that cold air flooded much of the United States early in the season and remained fairly widespread through much of January and February.
Some of the missing features were replaced by others that performed a similar function. While there was no dominant western U.S. high as we look for in the PNA+ pattern, there was one not much farther west that occurs with the negative phase of the Eastern Pacific Oscillation, and it provided enough of a northwest tilt to the flow over the continent to keep the cold air pressed our way.
The western U.S. low with the negative PNA actually helped sweep some of an “atmospheric river” from the Pacific our way — take note, as this is occurring now, inundating California — creating a sort of southern stream moist flow like we often see in El Niño.
And, finally, an atmospheric traffic jam in Canada surrounding a lobe of the polar vortex created a sort of blocking pattern even though high pressure was not present in the places we normally look for such a block. This kept the cold air and jet stream flow forced more southward.
In short, the Feb. 12-13, 2014, winter storm formed in a narrow window when it could, in exactly the right place with sufficient cold air and a textbook track to bury our region, even though broader atmospheric patterns weren’t all that conducive. It is worth noting that the infamous 1993 Superstorm — often called the Blizzard of ’93 in much of Virginia — also occurred with key oscillations in opposite phases from what is typical for large eastern U.S. winter storms.
This is why we need to be careful to avoid overly definitive declarations that winter storms or other weather phenomena absolutely must or cannot occur with certain combinations of large-scale atmospheric patterns. You can almost always find an exception to the rule sometime in our weather history.
Journalist Kevin Myatt has been writing about weather for 20 years. His weekly column, appearing on Wednesdays, is sponsored by Oakey’s, a family-run, locally owned funeral home with locations throughout the Roanoke Valley.
