Tuesday, 11:55 a.m.
If model trends are to be believed, then this disturbance flying across the South today and heading northeastward toward the East Coast this afternoon and tonight will end up spreading more snow farther north and west than most anyone had previously thought! Here's what that wave looks like:
There is really two aspects to this system. One of the main plume of moisture that is ultimately tied to the upper-level low in Mexico:
That streamer of moisture, working alone, would probably keep the snow and ice confined to southern Mississippi, southern and eastern Alabama, then across Georgia and the Carolinas to southeastern Virginia. Unfortunately, there's a second area of enhanced moisture farther north over the Ozarks into Kentucky and Tennessee, and that's helping to draw the moisture farther north. Even though surface dew points are extraordinarily low, snow is breaking out in parts of Tennessee, like in Knoxville, Chattanooga and Oak Ridge.
Another contributing factor to a farther north and west snow shield may be the presence of the downstream over the Atlantic - far enough offshore that the storm isn't going to develop rapidly and hand a sharp left turn, but close enough that it may be able to deflect the whole system just far enough to the left that it brings accumulating snow, barely, to the big cities from Washington, D.C., to Boston.
That, of course, is hardly the big story. That's reserved for areas farther south, really from the Delmarva Peninsula through southern and eastern Virginia down into the Carolinas and Georgia. In much of this area, there will be plenty of snow that will shut things down for a while. Here's the most recent snowfall forecast here at AccuWeather.com:
That 1-inch line may well be expanded farther north and west to Philadelphia and Washington, D.C., if not back to the Shenandoah Valley.
Even farther south, the air isn't cold enough to support snow, at least not until the wave passes and the air aloft cools some more. Along the Gulf Coast itself, it'll be mainly a rain to freezing rain to sleet transition, as the truly deep cold air that would support all snow doesn't reach the coast until the storm is largely over. That includes the Florida Panhandle and much of southern Georgia over to coastal South Carolina. Either way, snow or ice, it will be a disruption to travel throughout the region the rest of today and tonight. Even tomorrow in the wake of the storm, it will be very cold with little melting! What does melt may refreeze at night and stay frozen into Thursday morning before sunshine can push temperatures farther north of freezing to melt the snow and ice off the roadways and dry things out.
The other big story, of course, is the brutal cold. That continues in most places from the Mississippi Valley to the East Coast. There will be a disturbance crossing the northern Plains tomorrow afternoon and the Midwest tomorrow night and early Thursday with some snow, but its initial impact will be to pull warmer air into the region, even if it is briefly milder. Another push of arctic air will follow the front into the Dakotas and the Midwest, but it won't get nearly as far south as this arctic outbreak, nor will it be as bitter where it does move in.
Then our attention will turn to a couple of features attacking the Northwest and the West Coast later tomorrow and tomorrow night. This will actually mean some rain for parts of Washington and Oregon down into northern California, a rare treat this month - indeed, this entire winter season! Yes, there will also be some snow in the mountains, but the overall moisture will do little to positively impact the ongoing drought.
These features will combine into one larger storm Friday in the lee of the Rockies over the Texas Panhandle and southeastern Colorado. From there, the storm will move to the east then head across the Ohio Valley toward the eastern Great Lakes. The 12z GFS model has finally come around to the thinking of the European and the Canadian model forecasts of recent days.
Snow is the most likely form of precipitation from northern Missouri through northern Illinois toward southern Michigan, including cities like Chicago and Detroit, though enough warm air could sneak into southeastern Michigan to change the snow to ice or even rain. That's almost a certainty in the mid-Atlantic region despite how cold it is now. That said, many places north of the Mason-Dixon Line into southern New England will see the snow transition to ice before it warms up to the point where rain falls.
If all goes according to plan, though, this will all be gone by Sunday, meaning dry, cold weather Sunday evening in and around New York City.
That will transition us into February, and while the extreme cold may not be as prevalent, it doesn't look like a warm first half of the month from the northern and eastern Rockies to the East Coast. Moreover, it looks to become a very active weather pattern, with storm after storm after storm likely to run across the country.
The record warmth of recent days will be replaced by a much colder air mass following a cold front moving from the Ohio Valley to the East. Rain will change to snow in the higher ground of upstate New York and northern New England.
Nicole crossed Bermuda Thursday morning as a major hurricane. Two storms will blast the Northwest with high winds and heavy rains in the next 72 hours, forcing warmer air out into the nation's midsection.
Matthew is a dangerous hurricane bearing down on the east coast of Florida. While it ravages Florida and parts of the Southeast into the weekend, it will spare the Northeast of its fury.
Major Hurricane Matthew is now a significant threat to the entire Eastern Seaboard Thursday through the weekend with with potentially destructive winds and excessive rains.
Heavy rain will soak drought-stricken areas of the mid-Atlantic over the next couple of days. Focus will then shift to Matthew and its potential to impact the Eastern Seaboard with more heavy rain later next week.
Summer has ended astronomically, but from a meteorological standpoint, there's plenty more warm weather heading into October from the Plains to the East.