Tuesday 10:30 a.m.
A storm bringing snow to Chicago today threatens to dump heavy wet snow from northern Virginia to eastern New England. The greatest chance of significant accumulations will be late tomorrow and tomorrow evening in the D.C.-Baltimore area, tomorrow night in New York City and later Thursday or Thursday night in Boston. From D.C. to Philadelphia, a major factor is how much rain there can be and how long it will take for pavement to become cold enough for accumulations to occur. If there is heavy precipitation, things can turn hazardous very quickly, whereas if precipitation is lighter, streets could remain wet throughout.
This morning you could see only a narrow zone of high pressure between the departing storm off the East Coast and the approaching storm from the west. The ridge axis is shown by the dashed line.
Here is a story about March snow:
In the chameleon month of March, few items change character more quickly than March snow. When a March snow begins, it seems to be swallowed up by the warm ground. The flakes melt as if vaporized on Star Trek. However, as the March snow continues, it paints the landscape canvas like a patient artist. First, the trees and wires are outlined in white, then the lawns and car tops are coated. Clumps of grass that started growing look like islands shrinking as the tide comes in. If the March snow is light enough, it can snow all day without bothering the roads, but if the flakes join together into cotton ball puffs, an oozing layer of slush starts to form, eventually thickening into a spongy meringue that splashes wildly with each passing car or truck. Carried to its extreme, a March snow shows its sinister side. Branches and trees are weighed down with the gluelike snow until they bend and break. Powerlines snap like matchsticks. Cars look like igloos. The morning after a March snow can seem like a day plucked from January. The slush has congealed into crunchy rocks and pebbles underfoot. The town looks like a Christmas card. Then the March sun goes to work. All at once, gutters turn to rivers. Piles of snow cause hidden swamps, waiting for unwary pedestrians to step into this urban quicksand. The plowed snow leaches a salty, cindery solution onto streets long after other snow has melted, always ready to smear the windshield. March snow: its changes match perfectly the pothole-lined winding road that leads eventually to real spring.
The wind has increased over the western Great Lakes. This pressure analysis shows tightly packed isobars from Lake Michigan westward and much looser spacing of those lines of equal pressure farther east. You can also see the circulation that is developing around the Carolina coastal low pressure area.
Note how far south snow is being predicted, but how no accumulation is indicated for the cities from DC to Boston. This apparently happens because the cold air rushes south, but by the time it reaches the East Coast, the storm developing over the ocean is too far east to cause any snow in the major cities.
A storm will form along second cold front. Its track and strength will determine when, where and if any snow will fall along the Northeast coast. The forecast video follows. After that, I show the GFS snowfall map from last night. It suggests no snow accumulations for the cities between D.C. and Boston. Stay with AccuWeather.com as the story unfolds. The north Georgia mountains may get snow before Buffalo does.
Here is that map. With borderline temperatures and great uncertainty on precipitation placement and amounts, the I-95 corridor from Maryland to Maine could have anything ranging from zero snow (and comments like "Where's all that snow they promised?") to the first accumulations of the season.
This map shows the pressure pattern as of 8 a.m. ET today (Monday, Oct. 27, 2014). A northwesterly flow is still in place across New England, but with weather systems moving steadily eastward, a southwesterly flow of warmer air is on the way.
All foliage colors have peaked across much of the interior sections of New York and New England, but this weekend will offer plenty of dazzling color farther south. This barn and wooded hillside scene was photographed 4 miles west of State College, Pennsylvania, this week.