Tuesday, 11:00 a.m.
A fast-moving, upper-level disturbance is in the process of carving out a weak low pressure area along the mid-Atlantic coast. Snow has swiftly moved across the mid-Atlantic region, with some rain in parts of Delaware at this hour! The snow will concentrate on New England this afternoon into tonight, with the heaviest snows from Rhode Island and eastern Massachusetts up into Maine.
There's also a trailing upper-level disturbance moving across Wisconsin into western Michigan at this hour, and it has helped to create a rather odd temperature configuration from the mid-Atlantic to the northern Plains! South of the track of the first feature, it's warming fast in Delaware and Maryland into Virginia, especially where there is some sun breaking through the clouds. North of there, it's cold. Then you have a trailing cold front extending from western New York down through northwestern Pennsylvania into western Kentucky. There's a nice spike of mildness in southwestern Pennsylvania ahead of this front, followed by more arctic air right behind it. Yet there's also been this odd warm wedge that came out of the Dakotas into southern Minnesota overnight in conjunction with the trailing feature. Here's the 10 a.m. temperature map:
And the Midwest:
This trailing upper-level feature will generate some snow showers this afternoon across the Great Lakes and Ohio Valley, but few places will get more than an inch of snow, and many won't get more than a covering. In fact, east of the Appalachians, with the boundary layer warming so much this afternoon, any precipitation that survives east of the mountains late this afternoon and early tonight could easily start as rain before the column cools to the point at which it may snow - assuming there's enough moisture left!
That's long gone by morning, and in its wake, it will be a chilly day tomorrow throughout the Northeast all the way back to the Midwest, but that's as cold as it will be for days to come.
The next main feature will come into the Northwest via British Columbia tonight and tomorrow. It will then dig into the Southwest Thursday, pulling colder air southward with it. The bulk of the cold air will go into the interior Northwest and northern Rockies at first, but then it will spread more east than south Friday thanks to the developing split in the jet stream. However, some of the cold air will make its way down the Front Range of the Rockies and to the southern Plains this weekend once the upper-level low comes out of the Southwest and a surface storm moves out of Texas and crosses the lower Mississippi Valley and heads into the Tennessee Valley.
This storm could have everything with it. I mean impressive warmth and reasonably high humidity by December standards is moving into the South and Southeast and trying to climb the Eastern Seaboard this weekend! Severe thunderstorms may erupt ahead of a cold front which is moving from the Mississippi Valley Saturday night and across the Tennessee Valley and Deep South on Sunday. There will be a fair amount of rain in the Ohio Valley into the central Appalachians, and perhaps even into the Northeast, and given the amount of warming that may accompany this rain, there may also be some flooding. And, of course, there will be some snow, though that may not be the main feature of the storm. Still, some snow is all but certain on the northwest flank of the storm, and that includes areas from eastern Oklahoma to Illinois and Michigan, including parts of northern New York state and northern New England. And even in these latter areas, that may also be accompanied some ice and rain for a time. Here's an initial broad brush snapshot of how this might look:
Yet another winter storm, though at least this one will be during the official winter season, which arrives Saturday at 12:11 p.m. EST. Up to now, all of this snow has been under the fall watch!
A quick shout out to a cycling friend from near Hershey, Pa., celebrating a birthday today! Beth, You got your snow - and a delay! Hope you can plan a great ride with friends in the mildness of Saturday! I'm jealous!
Good news, though. Only 55 days until 'Pitchers and Catchers Report.'
A pattern of extremes is once again unfolding across the country over the next week, with two shots of cool air interspersed with intense heat.
Despite the heat over the central and southern Rockies this week, an amplified pattern means cool air will dominate in much of the country for the rest of July.
Heat will resurface over the eastern Rockies and Plains this weekend and early next week, but the warming in the East will be much slower.
In the wake of the deep upper-level trough over the Great Lakes to the Tennessee Valley, a strong upper-level ridge is poised to blossom over the Rockies, one that will bring on the heat this weekend into the start of next week.
Beyond the big chill now engulfing the Plains, it will turn warmer and more humid in the East back into the Ohio Valley. The heat will be turned up in the northern and eastern Rockies and northern Plains into the Midwest this weekend into early next week.
The West is very hot, while it is turning much cooler in the Plains and Mississippi Valley. Before the cooler air reaches the South and East, there will be a lot of showers and thunderstorms, including severe weather and flooding.