A strong cold front pushed through the region this morning, with temperatures in the 60s overnight pushed back into the 50s by sunrise and into the 40s through the afternoon.
Scattered showers will continue through the afternoon and end later tonight. High pressure will move over the D.C. area Saturday making for partly cloudy skies and cooler temperatures in the low to mid 40s.
- 3pm Friday Temperatures (WeatherBELL Models)
Saturday night will be cold and dry, with low temperatures in the 20s and 30s in the region and dewpoints back into the teens to low 20s. This is all setting the stage for a disturbance to move into the region Sunday, with warm, moist air moving over the cold, dry air at the surface beginning Sunday morning.
- Winter Storm Watch from the National Weather Service
A Winter Storm Watch has been issued for the majority of the D.C. area Sunday morning through Monday morning. Southern Maryland and the Northern Neck isn't included in the Watch, but they still may have a little frozen precipitation before changing over to rain earlier in the afternoon Sunday.
- 4km NAM forecast for Sunday morning (Courtesy: WeatherBELL Models)
Precipitation is expected to start Sunday morning in the form of snow before changing over to sleet and freezing rain in the afternoon hours. At some point, enough warm air will get into the region to change precipitation to rain, but the question is how late in the day or into Sunday night it will take place.
If it happens earlier, much less of an impact can be expected, but if it happens later, there could be major complications in the region due to icing. Below is a look at one forecast model depiction for Sunday evening, still showing the blue 32 degree line south and east of the D.C. Metro.
At this point, we expect areas of precipitation to begin changing to rain come Sunday evening southeast of D.C. and it will be on the edge of changing in the D.C. Metro. Travel looks poor Sunday evening.
- 4km NAM Sunday Evening (Courtesy: WeatherBELL Models)
Here is Chief Meteorologist Doug Hill's discussion which I thought summed up the forecast perfectly,
"At this point we can tell you what is possible on Sunday…what we expect to happen on Sunday. Because temperature profiles will be so important, we cannot yet tell you for certain, what WILL happen.
More rain with slowly falling temperatures WILL continue tonight and perhaps into the morning hours Saturday. Breezy and chilly weather WILL tomorrow with skies becoming partly sunny. Even colder air WILL settle into the region Saturday night.
On Sunday, moisture WILL rapidly increase over the area and precipitation WILL begin to fall.. It WILL begin as snow in many areas and then mix with or change to sleet for a period and then change to Freezing Rain.
Eventually, when surface temperatures rise above 32 degrees, the precipitation will become just plain rain. This IS NOT a one size fits all forecast.
Different precipitation types with different effects WILL be the story all day Sunday. Adverse to dangerous driving conditions WILL DEVELOP. The most likely areas for this to occur will be along and west of the I-95 corridor.
The longer it takes for temperatures to rise above freezing, the greater the chances for these conditions. And in general, the farther north and west you are from D.C, the greater the chances of this happening."