* Winter storm watch Sunday morning to Monday morning *

10 p.m. update: No major changes to the forecast for Sunday and Sunday night. The latest run of the NAM model holds much of the region along (including the District) and west of I-95 at or below freezing through 7 a.m. Monday morning – which would mean a messy Monday morning commute for much of the area. It also would signify the potential for serious ice accumulation overnight Sunday, especially west of the Beltway. We will have much more tomorrow.

Radar & lightning: Latest regional radar shows movement of precipitation and lightning strikes over past two hours. Refresh page to update. Click here or on image to enlarge. Or see radar bigger on our Weather Wall.

From 4:50 p.m.: As the rain has fallen today, temperatures have steadily fallen, from above 60 at dawn to the mid-40s late this afternoon. Temperatures continue their slide tonight and remain cold through Saturday, setting the stage for Sunday’s winter storm.

Through Tonight: Periods of rain, possibly heavy late at night, and chilly. Lows dip into the mid-30s, with winds from the north at around 10 mph. We could pick up another 0.5″ of rain overnight, after about 0.5″ today (averaged across the region.)

Tomorrow and tomorrow night ( Saturday and Saturday night): Cloudy early in the morning with a 30 percent chance of lingering rain (briefly mixed with snow? western areas). Then, skies clear. It’s quite brisk, with highs 37-42. Winds are from the north at 10-15 mph, gusting over 20 mph at times. Slowly increasing clouds Saturday night, and cold, with lows 24-28 (suburbs-city). Winds from the north at 5-10 mph.

Sunday: Snow likely develops late morning into midday, gradually mixing with and changing to sleet as the afternoon wears on. One to two inches of snow/sleet is possible. Highs are around freezing. Winds from the north at 5-10 mph.

Sunday night: Sleet changes to freezing rain, with significant ice accumulations possible, especially in the colder western suburbs. Freezing rain likely changes to plain rain near the Bay during the evening, and may (or may not) change to plain rain along the I-95 corridor (and inside the Beltway) by pre-dawn.  Temperature slowly rise overnight from 27-30 to 30-33 in western areas and from 29-32 to 32-35 in eastern areas.

See our detailed write-up for more on the storm Sunday into Monday. And if you haven’t already, join us on Facebook and follow us on Twitter . For related traffic news, check out Dr. Gridlock.