Friday, 10:50 a.m.
One storm is now pulling away from New England, and the snow has all but stopped falling across the region. It has left an impressive blanket of snow, too! I'll post a graphic of snow depth just in the Northeast, where the storm brought as much as 20 inches of snow to parts of Vermont. However, suffice it to say there's snow on the ground in most of Pennsylvania, Ohio and Indiana, as well as large parts of Illinois, southeastern Missouri and parts of Arkansas, not to mention most of the Midwest.
The next storm is already gelling in the northwest Gulf and will streak from there to off the Virginia Capes later tomorrow. Here's the 12z Dec. 28 NAM surface forecast for 18z Saturday:
Here's an interesting map from the 12z NAM - total precipitation through Sunday morning:
If you're struggling to read the key to that forecast, the NAM now has over 1/2 of an inch of liquid from the south shore of Boston to the northwest suburbs of New York City and much of New Jersey, with a secondary max of over 1/2 of an inch in West Virginia. It actually prints out about 1.5 inches of liquid over Nantucket Island. Somewhere northwest of there and south and east of I-95, given that kind of printout, you might see 6-12 inches of snow where it is, indeed, all snow. Again, that's if the 12z NAM forecast, the latest one, is reasonably accurate. The truth will probably be a little less than that. Still, it stands to be a better snowstorm in southeastern New England, specifically southeastern Massachusetts, southern Rhode Island and Long Island than virtually any place else.
From the southern third to half of New Jersey to south of Philadelphia to near Washington, D.C., to Roanoke, there will be a period where it isn't all snow, cutting down the snow totals there. Just northwest of that line, where it is all snow, an average of 1 to 3 inches is likely, with locally higher amounts of 4 or 5. Not a big snowfall, mind you, but snow nonetheless.
As that system exits stage right, a new system will enter the West, stage left. You can see the two separate features on the 500mb chart Sunday morning:
As this deeper trough moves into the Southwest, snow will break out in the central and southern Rockies later Sunday and Sunday night. This may bring some snow to the Colorado Front Range Monday and early Monday night, but there's apt to be a little more farther east across Kansas. The models diverge on their handling of this whole feature entering the new year. Much of it will be focused on whether the entire upper-level trough comes out Tuesday and Wednesday or if an upper-level low digs into southern California, northwestern Mexico and southern Arizona, with just smaller pieces being spit out of the Southwest and across the southern Plains and points downstream.
How that turns out will go a long way in determining how much snow can fall in places east of the Mississippi entering the new year, and it will also play a role in how much arctic air can sweep through the Midwest to the Northeast.
Four cold fronts will bring cooler air across much of the country in the next few days, with the cool air reaching the East and the South by the weekend.
A cold front will organize on the Plains at midweek, and as it charges eastward Thursday and Friday toward the East, it will generate strong to severe thunderstorms.
Late-summer heat in the northern and eastern Rockies and western Plains will expand eastward in the coming days as a strong upper-level trough digs into the West tomorrow and over the weekend.
Once the storm bringing wind and rain to the East Coast departs on Friday, most of the country from the eastern Rockies to the Northeast will be warm, while it turns cooler in the West.
Most of the country will be dry the rest of the week, though a storm moving up off the East coast will mean rain, while a cold front brings some rain into northern California and the Northwest.