Still no signs of big snow potential from Sunday-Monday storm

European model forecast is similar to others showing D.C. area caught between two areas of low pressure Monday morning. Not a great spot for meaningful snow, especially with no high pressure to the north. (StormVistaWxModels; adapted by CWG)

European model forecast is similar to others showing D.C. area caught between two areas of low pressure Monday morning. Not a great spot for meaningful snow, especially with no high pressure to the north. (StormVistaWxModels; adapted by CWG)

Never say never for snow in March. But as we get closer to our next weather-maker late Sunday into Monday, it continues to appear that even if we see some snow, meaningful accumulation (if any) would be hard to come by in the District and nearby suburbs:

70% chance: Minimal impact with conversational light snow, mixed with rain and sleet, and to little to no accumulation inside the Beltway and S/E; up to 1″ or so N/W of the Beltway and northeast toward Baltimore.

30% chance: An inch or so of snow inside the Beltway; 1-3″ north and west of the Beltway and northeast toward Baltimore.

Storm Timing: Light rain, perhaps mixed with snow and sleet, develops Sunday afternoon or evening. Intermittent precipitation possible through Monday afternoon.

Why so pessimistic on snow, the snow lovers ask?

The overall setup, with low pressure tracking north into the Ohio Valley and transferring its energy to a new area of low pressure off the coast, would be iffy for significant snow in the D.C. area in mid-winter, let alone late March.

Things might be more interesting if there were high pressure parked to the north helping to lock cold air into the area, but alas that is not the case. Heavy precipitation could also generate the cold air needed for snow to stick in a significant way, but being caught in the energy transfer zone means we’re more likely to see light to moderate precipitation rather than moderate to heavy, though there is potential for a period of heavier stuff Monday afternoon as the coastal low pressure gets going.

Here’s what our winter weather expert Wes Junker has to say about the situation:

The models continue to predict that a low will track to the Ohio Valley with energy then transferring to the coast.  Storms going through such a transition often disappoint snow lovers as one area of heavier precipitation tracks into the Ohio Valley with the parent low and then a second batch develops too late to give D.C. any significant accumulating snow.  There is also a tendency to dry slot after an initial period of light to moderate precipitation.  A low track to our northwest also often allows warm air to come in at some level. 

The European model has been forecasting such a scenario for several runs. GFS has now shifted toward a similar European model solution  keeping surface temperatures around the city above freezing.  They both favor little or no accumulations for the city and only minor accumulations toward the mountains.  The NAM remains colder and more bullish but has trended to a stronger low in the Ohio Valley. 

There is still time for the models to shift back toward a colder, snowier look but the odds seem to be growing that this will be a conversational snow rather than an accumulating one.

We’ll of course still need to watch this storm closely given colder air won’t be too far away — areas north and west of the Beltway and northeast toward Baltimore have a better chance of seeing a coating to an inch or so, though even that might be mainly on grass, with a few inches possible further west toward the mountains. The latest European model suggests the best chance of heavier snow would come Monday afternoon as the coastal low intensifies.

For now, though, we favor a low-impact scenario for most of the metro area.

Also on Capital Weather Gang

World Water Day: A forceful reminder that the U.S. is running out of fresh water