Tuesday 9:45 a.m.
A patch of moist, chilly air has been causing showers and some wet snow from northern Ohio into western Pennsylvania and southwestern New York state this morning. The system should weaken as it moves eastward. Dry air is promoting some clearing east of the Appalachians from southern Pennsylvania and central New Jersey on south.
A major storm will take shape over the western Plains tomorrow. It will strengthen and move to just east of Chicago by Thursday afternoon, then to near or just north of Buffalo by Friday morning. A sharp cold front extending south from the storm will whip eastward to reach the East Coast Friday morning. There will be showers and gusty thunderstorms with the front, then an outbreak of lake-effect snow from the lakes into the Appalachians. It would not be surprising to see snow flurries all the way to the coast. This morning's GFS predicts it for Saturday morning (some other models are drier).
Even though winter's first weekend will be cold in the Northeast, it will not be unusually chilly for late December. And, when the next storm develops, it looks like the major snowfall may be in the eastern Plains over to the western Great Lakes. Warming will occur farther east, though there is a chance that cold air will become entrenched in parts of New England just like we saw from the last storm.
Here is one snapshot from this morning's NAM run, depicting the precipitation it predicts for Saturday between 1 and 7 p.m. ET. The rain/snow line should be close to the Pennsylvania-Maryland border.
it appears a storm will form the Southeast and trek toward eastern New England this weekend. Current models suggest this will turn into a mostly rain event in the I-95 corridor...
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.