WASHINGTON – The holiday season is upon us! Christmas is just a few days away, and for the most part, it does look like the weather is going to cooperate over the holidays.
In fact, Christmas Eve and Christmas Day could be two of the warmer days of the year for our region, which is not saying much. Washington, D.C. is running more than six degrees below normal for the month so far, temperature-wise, our coldest December since 2010.
Some sunshine is expected for Christmas Eve with temperatures in D.C. expected to rise into the middle 50s with light winds. It should be one of the more comfortable afternoons of the month with sunny skies.
Clouds will increase during the evening hours, though some rain showers possible in the first half of Christmas Day. These should be scattered about though — the holiday does not look like a washout.
All things considered, not a bad Christmas! But no threat of a white Christmas either for those that were looking for some holiday snow.
It is the Friday after Christmas that bears watching! Cold air gets pushed southward into the Mid-Atlantic on Friday morning, courtesy of a high pressure system pushing through eastern Canada.
A steady northeast wind will “trap” this cold air southward, something that often happens in this region during the winter months due to our proximity to the Appalachian Mountains to the west.
By Friday afternoon, a fast moving storm system is expected to cross the region from west to east. As mid-level winds are out of the southwest, southern moisture will gather along a warm front, meeting the cold air stuck across the region and causing precipitation to break out.
While some initial snowflakes at onset are possible, especially in our northern zones, the depth of the cold air is forecast to be pretty shallow. So, the bulk of precipitation locally is forecast to fall as sleet and freezing rain.
Sleet is ice pellets, snow that has melted to rain, only to refreeze before hitting the ground. A slushy accumulation of sleet is enough to cause travel issues and slick spots. Freezing rain falls like rain, but freezes on contact with a surface where temperatures are below freezing.
Ice is a major concern to travelers. Such mixtures are difficult to pre-treat roadways for, as the more liquid nature of the precipitation can lead to runoff of any pre-treatment chemicals.
The question with shallow cold air events like this one is how long will the cold air hold on, and how fast will the region transition over to all just plain old rainfall, if they even do at all.
In similar past events, weather models tend to underplay how long cold air lingers in the D.C. region, leading to a longer than expected sleet and freezing rain event. This is particularly true in our northern zones, where cold air just naturally hangs on longer.
Winter advisories seem likely for parts of the region on Friday due to the threat for icing and hazardous travel conditions. Those traveling, especially Friday afternoon and evening, should exercise extreme caution.
Snowfall wise, the best chance of getting any snow would be at the very start of the event when the depth of the cold air is deepest. Some models do suggest there could be a quick burst of snow in our suburbs north of D.C. that could put down a quick coating before a transition over to a mixture of sleet and freezing rain.
For travelers, heavier snow looks more likely across the Northeast. Cities like New York and Boston could squeeze out a few inches of snow, while interior regions could see 4-8″ of snowfall, which is likely to disrupt travel on a regional basis.
After the system moves out of the region early on Saturday morning, the remainder of the weekend looks rather mild weather wise.
Impacts from the Friday system should not linger as temperatures rise well above freezing on Saturday with 50s possible by Sunday. Though a few showers are possible Sunday as well, it does not look overly impactful for travel.
The next blast of strong, cold winter air is set to move into the D.C. region just ahead of the New Year’s Holiday. Tuesday in particular looks especially cold, with high temperatures struggling to make it above freezing across much of the region.
At the moment, it does look like this next burst of cold will come without any winter weather threats, but it is far enough in the future that we need to monitor for potential forecast changes. We will keep you updated!
From all of us here on the FOX 5 Weather Team, happy holidays and Merry Christmas! Have a safe and wonderful holiday.