7:00 AM | **Ice/snow chance late tonight and a bigger threat on Sunday with snow/ice accumulations likely**
Cloudy with occasional rain this morning and then steadier rain develops this afternoon, temperatures have already peaked for the day in the low 50's and will gradually fall as the day progresses and NW winds intensify
Cloudy with rain during the evening hours and then the rain could mix with or change to sleet and/or snow towards morning as it winds down, little to no accumulations expected, lows by morning in the low 30’s
Becoming partly sunny, cold, breezy, low 40’s
Mostly cloudy, colder, low-to-mid 20’s
Cloudy with snow arriving between midday and mid-afternoon and then mixing with or changing to sleet and freezing rain, up to a couple inches of snow and ice accumulations are possible later Sunday with tricky travel conditions for awhile, mid 30’s
Mostly cloudy, cold, rain likely, low-to-mid 40’s
Mostly cloudy, windy, cold, maybe some rain or snow early, low-to-mid 30’s
Partly sunny, very cold, near 30
An Arctic front that has been progressively sweeping across the nation will slow down and then stall out today in a southwest-to-northeast fashion near the east coast allowing for a couple waves of low pressure to ride along its temperature gradient boundary zone. The first wave will generate periods of rain around here today and tonight and as colder air continues to filter into the region in the overnight hours, the rain could very well mix with or change to sleet and/or snow in the northern and western suburbs before ending early Saturday.
After a break in the action on Saturday, a classic "cold air damming" event will take place on Sunday and Sunday night. Another wave of low pressure will spread wintry precipitation into the region on Sunday that will continue into Sunday night before changing to plain rain. The current thinking on the timetable and precipitation type is as follows (subject to change): snow is likely to arrive between the mid-day and mid-afternoon hours and then it should mix with or change to sleet and/or freezing rain before a change to plain rain later Sunday night. Accumulations of up to a couple of inches of snow and ice are possible later Sunday and travel can get tricky for awhile as there is likely to be an extended period with temperatures near the freezing mark. By Monday, milder air should win out along the I-95 corridor where the precipitation is likely to fall as plain rain, but not too far to the north and west of the big cities, frozen precipitation could linger. By Tuesday, the next Arctic invasion will begin and very cold conditions will persist through the mid-week in the Mid-Atlantic region as well as across much of the country. [A detailed video description of "cold air damming" is available on our "Meteorology 101" page].
One final interesting tidbit: there is a report this morning that the 8am average temperature across the continental US was 18.1 deg F which is colder than at any time during last winter. According to weatherbell.com, the lowest average CONUS temperature at any time last winter was 18.9 deg F.