Category Archives: Weather Outlook

Light Snow Possible for late Saturday in PHL

A weak low pressure disturbance will move along a frontal boundary just to our south late Saturday afternoon.

There are increasing signs that a last minute intensification will occur as the disturbance reaches the coastline.

If this occurs  in the evening rather than during the daytime hours, the high March sun angle won’t be a factor and some snow accumulation is possible.  Current NAM QPF values are about 0.33 inches water.  Current thermal profiles support the precip falling mostly as snow, but light QPF in March can be difficult to accumulate, unless it occurs at night.

Each recent successive model run has shown slightly greater intensification.    Not a sure thing, but it needs to be watched.

The long range models are suggesting a continued overall somewhat cold  pattern with another deep cold outbreak the end of next week, followed by moderating temperatures.

Philly Winter Weather Update

Wednesday AM Update: Last night’s NAM has backed off on the snow quite a bit, with much of the precipitation moving past us to our north.  The GFS continues with light precip early Friday morning.  Will have to wait on this forecast .

Sunday’s potential forecast snow has also changed, with a more definitive movement to our south, missing us.

The newest possible storm is Tuesday to Wednesday timeframe.  As mentioned many times this season, the lack of model continuity lately has made forecasting beyond a two day timeframe very difficult.

Some snow is looking likely for late Thursday night into Friday morning as a disturbance rides along a stalled frontal boundary.

Despite much recent model run inconsistency, the forecast for this early Friday period has become more consistent

The models are cranking out about 0.30 inches of water falling as snow. It’s extremely difficult to predict accumulations in March, as solar insolation through clouds tends to melt all but the heaviest snows on dark asphalt roadways.

If this were January, we would be talking about 3-4 inches but in March, snow accumulation discussions become more academic with “grassy” surface vs road accumulations. Ground temperatures are starting very warm, further reducing accumulation potential. That said, expect some accumulation at daybreak (due to the onset occurring at night) and messy driving during the morning commute. A coating to an inch, maybe two, is possible.

Looking ahead, a storm on Sunday is expected to keep much of its snow in Maryland and Virginia, but that could change.

Another potential snowfall is possible next Tuesday night.

Stay tuned.