10:40 p.m. update: Our late-evening model data has also trended slightly warmer and drier (as did the early-evening model information). So again, odds are tending to favor roads being more wet than white in the morning, except for colder areas from around northern Loudoun, northern Montgomery, northern Howard counties and to the north. That said, we can’t rule out a heavy band of snow developing somewhere in the area late tonight into the morning. And with temperatures generally expected to dip to around 33-35 toward dawn, such a snow band could briefly lower the temperature to around freezing and whiten and slicken the roads just about anywhere.

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This is one of those situations where you’ll want to look out the window (and check in with us) when you wake up to get a sense of the conditions. As far as total accumulations, as we said earlier, this evening’s model data suggests the middle to lower end of the snow totals in our accumulation map below. But this remains a difficult forecast, and a couple of well placed heavier snow bands could easily push some areas toward the higher end.

We’ll be back by 5 a.m. with the latest on conditions outside and the forecast…

9:20 p.m. update: The first wave of model information coming in this evening has trended a few degrees warmer late tonight and tomorrow — staying above freezing except from northern Loudoun, northern Montgomery, and northern Howard counties toward points north (see graphic below) — and drier as well. That would suggest roads to be more wet than white heading into the morning commute for most of the metro area except far north, and overall the middle to lower end of the snow totals in our accumulation map further down in this post.

We are, however, still waiting for what has been the consistently snowier model to come in, which should be around 10:30 p.m. We’ll be back with an update around that time.

From 5:30 p.m.: Temperatures pressing into the mid-40s marked a mild afternoon ahead of the winter storm streaming into the area. Rain showers will zip into the region as the evening wears on and gradually mix with and turn to snow from northwest to southeast overnight. Occasional snow continues at times Tuesday, with the possibility of a heavier burst in some locations, most likely but not for certain north of D.C.

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[Programming note: This post will be updated through the evening as precipitation develops and to make any necessary modifications to the forecast.]

Through Tonight: Light rain develops this evening, with temperatures still in the 40s. The turning point, when rain starts to transition to snow, should be between about 10 p.m. and 3 a.m. from northwest to southeast. Overnight temperatures fall through the 30s, closest to freezing in our colder north and west suburbs – where an inch or two of accumulation along with some slick road surfaces are most likely by morning.

Conditions in the morning may be highly variable – with some areas slick, other areas just wet. We encourage you to check our updates in the morning to get a lay of the land before heading out.

Tomorrow (Tuesday): Periods of snow are likely. Whether and where substantial accumulations occur depends on the development of a heavy area of snow, which will probably be narrow and localized if it forms. We think the best chance of localized heavy snow band is north and northeast of the District, but models are having a difficult time coming to any consensus on this. Where snow does not fall steadily – most likely from D.C. south – temperatures are likely to remain above freezing, preventing much accumulation. Highs temperatures range through the 30s, coldest in our northern suburbs and highest to the south.

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Late in the afternoon and into the evening, temperatures fall back below freezing with continuing snow showers, meaning roads could be slick in some areas for the PM commute.

See my forecast through the weekend. And if you haven’t already, join us on Facebook and follow us on Twitter and Instagram. For related traffic news, check out Dr. Gridlock.