TL/DR –
A snowfall of light to moderate intensity is predicted for the D.C. area on Friday night, with a potential accumulation range of a coating up to 3-4 inches. The forecast is uncertain as to the exact amounts and locations, with a potential shift in the storm track and a possible localized zone of heavier snow of 4 inches or more. The report anticipates that the snow will begin falling at 8 p.m. Friday and end by 10 a.m. Saturday, with improving road conditions towards the latter end of the storm.
Forecast for Light to Moderate Snowfall in D.C. Area Intensifies
Forecast confidence is heightening for a moderate snowfall in the D.C. area this Friday night. The potential accumulation range is projected to be a coating to approximately 3 or 4 inches. We’ve also been able to provide an initial estimate of the regions that may see the lower, middle and higher end of this range. Look at the map above for more details.
The certainty of exact snowfall amounts and locations remains at a medium level. This is due to the possibility of the overall storm track shifting slightly, potentially causing a localized zone of heavier snowfall of 4 inches or more. However, it’s too early to predict such a zone’s location.
The odds of D.C. area receiving at least an inch of snow have increased by 20 percent in the last 24 hours, standing currently at 70 percent. This storm is a “clipper” system traveling from west to east. Anticipated to pass through our south, it’s expected to result in mostly snow for most of the region.
The timing of the snowfall is likely to lead to accumulation on untreated roads, despite temperature being above freezing. Any travel disruptions should diminish by late Saturday morning.
A Brief Overview of Snowfall Timing
8 p.m. Friday to midnight Saturday: Snow starts from west to east, potentially beginning as rain or a rain-snow mix in downtown Washington and the southern and eastern parts. Temperatures will be in the mid-30s to near 40.
Midnight to 4 a.m. Saturday: Snow could be moderate to heavy at times, accumulating on roads. Temperatures will range from upper 20s to mid-30s.
4 to 7 a.m. Saturday: Snow tapers from west to east. Temperatures will be from upper 20s to low 30s.
7 to 10 a.m. Saturday: Road conditions improve. Temperatures will rise through low and mid-30s.
It’s clear that snow accumulation will be easier in the northern parts of the region. In the southern half, warmer temperatures may delay freezing and reduce snow accumulation, adding to forecast uncertainty.
Models have been consistent in their predicted storm track. This type of storm is usually more predictable than the nor’easter that was hard to predict earlier this week.
Two major uncertainties remain: how quickly temperatures will fall to near freezing, and if the snow will fall intensely enough to allow for efficient accumulation. Additionally, the possibility of a band of heavier snow developing is still in question. If such a band becomes evident, it might necessitate an update to our forecasts.
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