This is a map of current weather observations in the Mid-Atlantic states. The little lines attached to the circles indicate the direction the wind is coming from.
Take note of the winds in western PA, WV, and VA. Notice they are out of the west.
Now take note of the winds in eastern PA, NJ, DE, and MD. Notice they are out of the east.
Draw a line down the middle and you get our trough. When winds are blowing in different directions toward one another, air must be rising in the middle somewhere. Rising air means precipitation. Thus we get snow.
- Timing: 9 pm Mon – 7 am Wed.
- Snowfall: 5-6”
- Snow intensity will vary. Light most times, with a few bursts of heavier snow also. And it will even stop snowing at times too.
- Longer duration event.
- Strong upper low develops area of low pressure off the east coast.
- Inverted trough will develop W-NW from surface low off east coast.
- Trough will orient itself SE/NW between Washington DC and Allentown.
- Trough will move very slowly NE Tue and Tue night.
I do feel that the trough is likely to set up south of Lancaster, but north of Baltimore and then slowly shift north Tue. This will bring us snow on and off for most of Tue and Tue night.
The challenge here is that these troughs are notoriously hard to forecast and always have some surprises to give. Someone (south of us) in southern PA will likely get a surprise heavy snowfall (10”+). I just don’t believe it will be us.
Rest of the Weeks Weather Points:
- Growing Colder: Temps sliding a few degrees each day starting Tue.
- Bitter Cold: Saturday - Monday will be bitter cold. Temps may dip below zero Sun morning.
- Snow: Moderate snowfall possible Fri night - Sat morning; and light snow possible Mon.
Tuesday: 32. Cloudy. Periods of snow. Light to moderate at times. 4-6" total by Wed morning.
Wednesday: 29. Mostly cloudy. Snow showers.
Thursday: 26. Sun and clouds. Flurries. Gusty wind at times.
Friday: 26. Increasing clouds. Light snow arrives overnight. Few inches possible.
Saturday: 18. Light snow ending very early. Clearing. Very cold. Windy.
Sunday: 16. Sun and clouds. Very cold.
Monday: 24. Mostly cloudy. Some light snow possible. Not as cold.