Wednesday 8:30 a.m.
I've been trying to picture how the changing weather scene will appear in Chicago during the next few days. Today, it's almost like early spring. The temperature started at frosty levels but will head toward 50 this afternoon. Overnight, the temperature will drop through the 30s. Now, since snow, cold and wind have been mentioned as starting tomorrow, the first look outside may give the impression it was all hype. It's been a snowless winter so far, and we wake up Thursday morning and nothing drastic is happening. Then, as we go through the day, it starts to snow. At first, the snow melts because it has been mild and the cooling process will start out slowly. In the afternoon, it gets colder, the snow falls more heavily and we see everything getting covered. The snow hides the thin coating of ice forming underneath. Finally, the wind cranks up tomorrow night. As temperatures fall through the 20s, blinding snow is streaming almost horizontally. Travel becomes an ordeal. Snow on the ground drifts and whips around in little whirlwinds. The wind always makes those curls and twists on windy days, but unless the air is carrying something like leaves, or dust.... or snow... we don't notice it. As the snow continues through Thursday night, you can see it lit up by all the street lights... and the sky even has a tint of orange or red amidst the ocean of falling snow. On Friday, the snow is mostly over, but the wind continues to cause blowing, swirling and drifting. However, the cleanup is underway, and the weekend will be cold, but much less windy.
In Philadelphia and New York City, expect a dose of heavy rain tonight, then a drying trend tomorrow with a hint of spring in the air. On Friday, however, there will be a big change to colder weather. There should be some early showers, perhaps mixing with snow, then gusty winds will tell us that it really is January. One of the computer models transforms an Alberta clipper into a coastal storm on Sunday, but we'll have to examine that situation during the next few days to see whether the picture on screen takes on reality... or not.
In the interior sections of central and northern New England, tomorrow morning will turn quite snowy, and in the mountains and Vermont and New Hampshire the snow will continue at varying rates right through Friday with a foot of new snow quite possible. Will sunsets next week look like this?
This map shows a draft of our starting time lines and expected accumulation from tomorrow's quick-moving East Coast storm.
A storm that has brought hardship and danger to parts of Texas and Arkansas with an assortment of ice and snow will send a swath of snow northeastward today and tonight. Here is a map showing our overall estimates as of 10 a.m. ET:
That could lead to tough travel at the end of the weekend. This map for Sunday at 7 p.m. ET shows where those troubles could be (north of the line with the label "snow rain line.")
This table shows the ensemble means for the next two weeks at Philadelphia: It suggests that whereas it does turn cold, any snowfall looks quite limited.
It is too early to be confident about any forecast for Christmas Day (or even the week before). However, the GFS model does go out 16 days, and it has a cold look for the Northeast exactly one week before Christmas.
As the flow aloft becomes southwesterly, mild moist air will spread northeastward from the Gulf States. In summer, this creates a hazy, very warm and humid scene for the Northeast. Now though, the warmth is slowly drained away as the moist mild air advances over cold ground. With temperatures near the saturation point, clouds form.