How Much Snow Do I Think Will Accumulate?

The “prolonged” — ‘storm’ being advertised (if you can call it that) from Wednesday evening through Friday morning is a classic over-running event.  Over running occurs where warm air glides on top of cooler air at the surface causing condensation and precipitation. It is a weather scenario that typically ends up being a snooze fest of intermittent light snow, not a heavy snow that accumulates quickly. Sleet may mix in at times along and south of Interstate 66 and then we will likely have prolonged lulls in activity during the day on Thursday and then again on Friday morning when the heavier moisture looks to escape south of DC.

Every model I am looking at has the textbook look of a bust for DC. Temperatures look to be marginal at best cutting down what is already looking like pathetic SLR (snow liquid ratios).

The system I am more interested in arrives next Tuesday which will be coming from the south with ample moisture.

Breaking News: Sometimes It Snows during the Winter

I’m going to be honest that i don’t foresee the upper-level pattern phasing in time for a decent snowfall in D.C. points north.

Saturday Afternoon and Evening “Overrunning Event – Light snow breaks out Saturday late afternoon mainly across the interstate 66 corridor/points north with 1″ of snow accumulating. Over-running occurs when warm air rises on top of cold air at the surface.

Saturday Night “Lull– Lift associated with overrunning weakens as coastal low begins to form off the NC coast.

Sunday “Snow Storm” (South of DC) – Coastal storm develops, but slips too far out to sea (because the northern branch of the jet stream is not phasing with the southern stream energy) keeping heavy snow threat across central Virginia (yes those of you who live along a line from Charlottesville, Virginia to St. Mary’s county in Maryland).

My rather pessimistic suspicion is a result of looking closely at some of the latest individual ensembles below (courtesy WxBell):

Some of these scream “DC Snow-Hole”

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DC Area Snowfall Accumulation Map Posted for Friday March 10th

  • A mix of rain and snow will develop across the Washington Region on Friday morning.  The mix will gradually change over to light snow showers during the afternoon hours mainly across our northern and western suburbs.

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