High pressure sliding eastward to the north Sunday and then remains strong and holding in from central Quebec to southeast of Maine on Monday as the complex storm system with front now off to our south works back northward as the colder air continues to comes in.
As far as sky cover Sunday, looks like we are or quickly end up, cloudy. The moisture streaking eastward to the north of the frontal boundary to the south can clip the city for a time later Sunday afternoon and evening, but really the best chance Sunday afternoon and early night will be in the south.
Later Sunday night, as cold air continues to come in from the north, the moisture from the south will increase and it looks like we have a more significant precipitation event starting very late Sunday night and continuing Monday with frozen precipitation and a slushy covering of snow and sleet possible in and around BWI.
There will be colder temperatures, and higher chance for a slippery coating to an inch of snow and sleet even on roads off to the north and west later Sunday night and Monday morning.
South and east of the city, there’s less of a chance. Once we get the change to all rain Monday midday and afternoon, rainy, cold weather continues Monday night.
The low pressure separate from this overrunning event moving into the Dakotas on Monday night that will track away from Lake Superior and northeastward across Ontario Tuesday. This low will have a cold front that sweeps eastward across our area Tuesday morning as low pressure will also try to develop along or near the coast of New England.
So we are still likely to have some precipitation early Tuesday morning before milder, drier westerly wind kicks in and clouds break for some sun. Out of this whole set up, there are going to be significant accumulations of snow across at least interior New England Monday night and Tuesday with some amounts over 1 foot.