In almost all of the cases, the amount of cold air is limited, which will make it hard but not impossible for any snow that falls to accumulate. Accumulation chances will tend to improve north and west of Washington and in higher terrain.
In other cases, moisture might be in short supply depending on how storm systems track.
A little bit of luck, or misfortune, depending on your perspective, will be required for a significant snow event in the region.
First snow chance: Tuesday night and Wednesday (40 percent south of the Beltway, 60 percent chance north of the Beltway)
For the second time in five days, a major nor’easter will rapidly develop off the Mid-Atlantic and Northeast coast. While our region is likely to see some light rain and/or wet snow Tuesday night into Wednesday, it looks as if the heavier precipitation and the prospects for significant snowfall should remain just to our northeast. But it’s a very close call, and we cannot yet rule out slushy accumulation, especially north and northeast of the Beltway.
Philadelphia is likely to see a major snowstorm, and significant snow could even come perilously close to Baltimore. If the storm shifts any farther south, the Washington region could get into sneaky snow accumulation.
A storm system tracking toward the region from the Ohio Valley is forecast to weaken and redevelop into a coastal storm near Cape Hatteras, N.C. As the storm tracks north adjacent to the Delmarva, it will intensify, draw in Atlantic moisture and pull down cold air. Light rain developing late Tuesday afternoon may mix with and change to wet snow Tuesday night into Wednesday.
For the most part, air (and ground) temperatures should remain above freezing, which should limit accumulation chances — especially if the precipitation is light. However, if any heavy snow develops, slush buildup would be possible late Tuesday night into Wednesday.
What makes this forecast especially difficult is that models forecast the storm to intensify rapidly just north of Washington, which puts it right along the edge of where heavier precipitation starts and stops. Since Sunday, models have generally shifted the storm’s track south, placing the Washington region closer to the zone that could have a period of accumulating snow. But it is probably still too far south.
“For snow lovers, the storm is more likely to be a tease than a significant snowstorm,” Junker said. “The only way to get significant accumulations would be for the low to bomb out far enough south to provide heavy precipitation and dynamic cooling across the area.”
For the moment, we favor areas north and northeast of Interstate 70 to have the best chance for accumulating snow, but this is a forecast you want to pay attention to. If the storm track (both aloft and at the surface) shifts south another 30 to 60 miles, this could suddenly turn into a meaningful winter storm in the D.C. area. Areas south and southwest of the Beltway have a lower risk.
Second snow chance: Thursday night into early Friday (30 percent chance)
This shouldn’t be a big deal, but a high-altitude disturbance zipping through the region could put down snow showers. This system, passing over the mountains, will be moisture-starved and isn’t predicted to tap any from the Atlantic. Nevertheless, models have consistently shown this feature, and some flakes may be in the air at times, especially in Washington’s northern suburbs. Most areas probably won’t see accumulation, although we can’t rule out a dusting, especially on grassy and elevated surfaces (car tops, trash cans, decks, etc.).
Third snow chance: Saturday morning (20 percent chance)
This one also shouldn’t be a big deal, if it even happens. A rather weak weather system will streak into the region Saturday morning. It may be cold enough for light conversational snow; that is, snow falling from the sky that does not accumulate much, if at all. Temperatures should mostly be above freezing when any snow falls, and its intensity should be light. It may end up as mostly light rain, especially if it comes in during the day rather than early in the morning.
Fourth snow chance: Sunday to Tuesday (50 percent chance)
This last snow event in the series is the one you may have already seen hyped up on your social media feeds. Some forecast models show this producing a ton of snow, especially in our colder areas well west of the Beltway (Loudoun and Frederick counties toward the Interstate 81 corridor).
Models show a rather classic evolution for a major Mid-Atlantic storm. Low pressure over Texas tracks across the south, drawing up moisture from the Gulf of Mexico, and then redevelops into an Atlantic storm off the coast of the Carolinas. It’s a slow mover and potentially dumps periods of moderate to heavy precipitation over the Mid-Atlantic for two full days.
However, the amount of cold air likely to be in place is marginal for significant snowfall, especially along the Interstate 95 corridor and to the east. Also, the storm track is far from being etched in stone. Today’s European and American model runs track the storm far enough south and east that the D.C. area would only be grazed by the storm.
“For us, I think it has more snow potential than the storm slated for Wednesday, but still will have to end up with a near-perfect track to garner significant snow,” Junker said. “Even with a favorable track, temperatures look to be marginal for accumulating snow.”
In short, there are a lot of question marks about this event, and it is way too early to buy into some of the snowfall maps you may see floating around. As time goes on this week, we’ll be able to drill down and talk more about specifics.
After this final (?) snow chance, there are signs that temperatures will trend markedly milder, starting around March 15. Cherry blossoms are then likely to transition toward peak bloom, and it will be about time to declare winter over.