The storm that came up the coast during the weekend included snow that changed to rain and freezing rain from parts of eastern Pennsylvania and New Jersey to eastern Massachusetts. This left trees, cars and many other things encrusted in ice as the storm departed. Now, a smaller, but still significant low pressure should move from Missouri this morning to near Delaware Bay tomorrow morning. One area of snow broke out ahead of this system and affected Cincinnati this morning. That snow should dissipate crossing the Appalachians.
A new area of snow now over southern Minnesota should expand southeastward to reach Chicago this afternoon, streak to Pittsburgh this evening, then reach the Philadelphia/New York City area late tonight or early tomorrow morning. This all suggests a slow evening commute in Chicago, then a slow morning commute tomorrow in Philadelphia and perhaps New York City. With an addition of Atlantic moisture, snow could adversely impact travel in Boston for their afternoon/evening commute.
This video has more:
This map shows a low pressure area over Missouri. The line extending east from the low is a front that separates cold air to the north from milder air to the south. As the mild air is forced to rise over the entrenched cold air, it cools to the saturation point, leading to clouds and then precipitation.
Putting it another way:
The great composer Ludvig Von Beethoven was born on this date in 1770. Of course this week, most people are trying to orchestrate their last Christmas purchases. If you're finished, you have our praise... but if unfinished, symphonies.
In the weather department, it has been cold and snowy recently from Maryland to Maine. With each storm, it was difficult to orchestrate movements. Temperatures will be on the low end of the scale today through Wednesday, and by tomorrow, a new storm will cause snow to spread across parts of the area. The key to our accumulation is the exact track of the storm. If the storm is conducted by to our north or south, the accumulation will B minor and shouldn't harmony one. However, if the main part of the storm comes toward us, we would C major snow: several inches. That would cause dischord and force people to improvise. However, if you keep your composer, you should be okay.
In the finale, chilly woods winds will return. Wednesday will be chilly, bassoon milder air will arrive. Temperatures late this week will not drop of clef, but instead go upscale. What about Christmas? You have my symphonies again about this, but that part of the forecast... is unfinished.
That moisture may move away for the afternoon, but thunderstorms will erupt farther west where morning and midday sunshine adds fuel to growing cumulus clouds. This forecast map from the main U.S. model suggests little or no rain in the I-95 corridor from Maryland to Maine tomorrow afternoon.
The surface pressure pattern looks chaotic today, with a multitude of trough lines. A few of these can be caused by glitches in the data, but any of the real ones could be all that's required to organize a short band of showers or thunderstorms. However, these features tend to change character with time, or they disappear and new ones pop up.
Here's a cool fact: even when Death Valley, California, has a temperature of 110 or 120 degrees, you only have to go up a little more than 3.5 miles to find temperatures at or below freezing.
It appears the dry comfortable air mass now in the Northeast will be replaced by a humid flow from the South Atlantic states for the coming weekend. An upper-air forecast map sequence in the video shows how this could happen. The following map shows the predicted flow from Florida to New Jersey Friday night.
This map shows the pressure analysis for the Northeast and Great Lakes. The gusty flow on the west side of the low pressure area adds a real autumn feel to the air.
Since individual lines and clusters of thunderstorms have limited life spans and change character constantly, forecasting whether it will or won't rain at any one time this weekend is difficult at best. One solution is to have your tablet or phone available with the AccuWeather.com app so you can see where all the storms are at the times when it concerns you the most.