The D.C. area is often near the rain-snow line. Here's why.

[elleng]

Here in the D.C. area, every winter, we live on the edge. That is, the narrow zone between below- and above-freezing air temperature. What side you fall on makes all the difference in weather hazards during a winter storm. It’s the bane of snow lovers and snow haters alike. . .

The difference between a day of soaking, cold rain, or accumulating snow, or an icy mix can depend on just a few degrees and a few miles.

Rain-snow lines separating subfreezing and above-freezing air masses commonly occur across North America during winter. They often develop in zones of strong temperature contrast. In the Mid-Atlantic, this contrast derives extra gusto from the region’s unique geography.

The Washington-Baltimore region, tracing the Interstate 95 corridor, sits near the midpoint between the mild Atlantic Ocean to the east and the chill-kissed Appalachians to the west. It also follows the “fall line” — where the hilly terrain of the piedmont flattens into the coastal plain. This puts the region in a spot where cold and warm air frequently mix.

During winter, some very mild air lies just off the East Coast, courtesy of the ocean’s Gulf Stream current, which is rooted in Caribbean waters. Yet roughly 100 to 150 miles west, the Appalachian spine is very adept at trapping and retaining subfreezing air that spills down from the north, out of Canada, from the high pressure anchored there. We call this Appalachian cold air damming. Chilly air is quite dense and stubborn; it sinks to the surface and is not easily scoured away unless a strong, mild wind kicks in from the south.' . .

Envision a ramp of subfreezing air stuck up against the eastern slopes of the Appalachians. This is the cold air dam or “wedge.” Overriding it on its east side is an inverted wedge of mild, moist Atlantic air. Low-pressure systems riding up the East Coast, also known as “nor’easters” — amid opposing wind currents from northwest and southeast — are very adept at pulling these airy wedges into juxtaposition and derive much of their energy from the ensuing, strong temperature contrast.'>>>

https://www.washingtonpost.com/weather/2024/01/02/dc-rain-snow-line-explained/?

[msongs]

1. log in required nt

[IronLionZion]

2. And time of day too

if it's warm when it comes down then it will be rain. Getting cold right after that can turn it into ice.

Or if snow comes down and then melts, and then freezes overnight. Or any number of issues.

I went into the office today and it was the least amount of traffic I have ever seen in my 16 years in this area. Tons of people chose to work from home today just in case. Even though the precipitation is forecasted for tomorrow afternoon.