The latest reliable computer models prefer a snowier scenario, with snow on Wednesday night until Thursday morning, a Thursday afternoon pause until evening, and then another possible period of snow Thursday night through Friday morning. This represents the third winter weather event in the past 10 days.
While many models place us in the right place for the snow, the shifts in where the front is located can produce very different results as the two waves pass. If one or both waves passed to the north, we would see more sleet and sleet or even rain, while Northern Maryland and Pennsylvania would get the most snow. But if one or both waves pass south, we might end up with a bit of rain, while central Virginia sees more intense snow.
Chance of snowing at least 1 inch: 70 percent
Chance of snowing at least 3 inches: 50 percent
Chance of snowing at least 6 inches: 25 percent
From Wednesday night to Friday storm scenarios
1) Snow Scenario – at least 3 to 6 inches
The Arctic front pushes south of the metropolitan area on Tuesday with forcefully cold air by Wednesday evening. Then, snow forms when winds from high southwest send relatively light air flowing through the forward region.
Snow will continue through Wednesday night, before likely stopping as the first wave of low pressure moves off the coast. Snow is likely to develop later on Thursday and continue into early morning Friday with the entry of the next wave.
The European Modeling System, UKMet Model and the Canadian Model support this scenario and suggest with high probability that it will produce at least three inches and possibly more than six inches in area.
2) Winter mix scenario – 1 to 3 inches of snow and some freezing / freezing rain
The rain will begin in the form of light snow on Wednesday evening, as the snow breaks out to mix with frost or freezing rain around the city, the south and the east due to the moderate air that moves at high altitudes. With the exception of southern Maryland, temperatures near Earth will still be below freezing point on Thursday.
As the first wave exits the coast, the front will likely sink a little further south, making the area deeper in the cooler air. A push of cold air will allow the next round of light rain to fall as snow on Thursday night through Friday morning.
The US model was suggesting this scenario, although its latest path has shifted towards a colder and snowy European camp.
3) Big Fault Scenario – Little or no accumulation of snow and ice
In this scenario, the heaviest precipitation with the first wave would lose us mostly to the north. Areas near the Pennsylvania border may see snowfall, but the rest of the area is likely to see a slight mix of rain event as moderate air is drawn into the area at low levels.
Then the second wave will come south enough that we often miss out on rain, although we might get some light snow.
This scenario favors the NAM model and some individual simulations in the American modeling system.
We can also see a mixture of these scenarios. For now, we are leaning towards a mixture of the first two scenarios. We will do our best to narrow the possibilities Tuesday.
Review the forecast for Sunday
On Sunday, we expected 1 to 4 inches long, mostly in grassy areas, over large parts of the area. This is evident in the map above, as all the sums shaded in blue on the left panel are within this range.
However, notes in purple went over four inches and started in a blooming scenario. It was mainly in the west and northwest in the mountains. Since temperatures were very marginal to build up, between 31 and 35 degrees, the quantities tended to depend on altitude. Mountainous and mountainous locations where temperatures dropped to 31 or 32 degrees saw snow accumulate much more easily than those above 33 degrees.
Our expectations for snow were very high in the area around downtown Washington and Alexandria and in the east and northeast. These sites have just seen a coating or so. While it snows here, the air and ground temperatures have proven to be too warm to stick around too much, and it just didn’t snowmatically enough to overcome it. Sometimes snow and rain mix. However, in parts of southern Maryland, where the snow was heavier, the volumes were as high as 2 to 4 inches in spite of similar temperatures.
Overall, our forecast performed well against forecasts from the National Weather Service and other outlets. We have accurately described the event schedule and when the rain turns into snow. We correctly conveyed that the storm would not have a significant impact on the region, and ranked it in Category 1 on our five-point scale.
The possibility that snow would have difficulty sticking was mentioned in lower elevations near town In our discussion. In hindsight we had to plug this into the snowfall map, which is something we’ll try to do next time when temperatures are marginal to build-up.
Another storm on Sunday is coming?
The fourth winter storm in two weeks is possible from Saturday night to Sunday. Computer models differ on how they evolved and whether they will produce significant rain, but there are some possibilities for additional snow, ice, and / or rain. We’ll focus more on that as we get closer to it.