Wednesday, 11:45 a.m.
The worst of the extreme cold is now beginning to fade, but not after setting a number of records yesterday and causing some troubles in terms of ice around Houston. There was even a bit of icy rain on parts of the Delmarva Peninsula early this morning as moisture from a disturbance crossing the eastern Carolinas snuck up to the southern half of the Delmarva peninsula for a brief time.
A reinforcing shot of arctic air will come through the Great Lakes into the Northeast tonight and tomorrow behind an upper-level trough of low pressure, as high pressure over Ontario today pushes into upstate New York and northern New England late tonight and tomorrow. Look at the early morning lows underneath that high:
Some of those same bitterly cold readings will show up tomorrow morning from Pennsylvania and New York state into parts of New England where the sky is clear and the wind is light.
In contrast to the very dry and cold air there, it will be quite moist across the Gulf Coast region. We've already seen one wave of low pressure move across the northern Gulf, with some of the rain still lingering in the eastern Carolinas and southern and eastern Georgia. The second upper-level trough cut across the Rockies last night, bringing a couple of inches of snow to Denver. As that feature slides into the southern Plains, rain and mixed precipitation has broken out in the Texas Panhandle this morning, and we expect a little rain at times this afternoon and tonight over parts of central and eastern Texas.
More robust rain will pelt Louisiana overnight, spreading eastward across the Deep South later tonight into tomorrow morning. The upper trough will carve out a surface storm over the north-central Gulf late tonight and tomorrow morning, and as warm, moist air is pulled in around, strong thunderstorms will erupt, largely offshore, but tending to bring heavy rain into parts of the Florida Panhandle and North Florida into Georgia tomorrow.
The storm will be cut off from the main flow of the jet stream, so it won't be a particularly fast mover. As outlined yesterday, the difference in pressure between this developing low and the surface high moving through New England tomorrow and tomorrow night will to generate stiff winds along the Eastern Seaboard. That will also help to spread a lot of low-level moisture well inland, meaning a pretty cloudy finish to the week all the way up through the mid-Atlantic.
Then another cold front will come along in the flow, moving across the Midwest Friday and into the Great Lakes Friday night, and then into the Northeast and Ohio Valley later Saturday and early Saturday night. Ahead of the front, it will warm nicely, especially where there is some sunshine, and temperatures in the afternoon may rise several degrees above normal for a rare change! This will be most noted over places that have no snow on the ground.
Alas, even that warmup will be brief, especially from the Midwest and Ohio Valley into the mid-Atlantic and New England, as a smaller chunk of arctic air will move in behind the front. And most of this will be restricted to areas from the Great Lakes to the mid-Atlantic and New England, which is depicted nicely on the GFS ensembles for Sunday:
There will likely be a second little front and weak surface storm that will zip across the Great Lakes Sunday night and across the Northeast Monday. The 12z GFS forecast for Monday morning:
It actually wouldn't shock me if Monday turned out fairly mild from the Ohio Valley to the mid-Atlantic ahead of that front with some sunshine and good mixing and a strong March sun, perhaps even leading to an above-normal day.
After that, the focus will shift much more to the West Coast, where a storm coming inland Monday will bring rain and mountain snow to the Northwest. That storm will track across the country, and it will have a bearing on the weather from the Great Lakes and Ohio Valley to the Northeast and mid-Atlantic in one form or another. The details of that are yet to be determined, but it does look like a much bigger chunk of arctic air will be unleashed on a much broader area of the country in the wake of the storm for the second half of next week.
A dominant ridge will keep it hot from the Ohio Valley to the East into next week, while the disturbance north of Cuba is slow to develop as it approaches the southeastern Gulf of Mexico.
Two systems will delay the onset of warm weather in the Ohio Valley and the East over the next week or so, but then it should get warm all across the country heading into the Memorial Day weekend.
A turn to much colder air over the Northeast and mid-Atlantic states will set the stage for a rain and snow storm later this weekend before it turns much warmer later next week.
It's warm now, but will turn much colder this weekend, with a storm threat later Saturday into Sunday. Warmth will return by the second half of next week.
Though it is cold now east of the Mississippi, with a couple of opportunities for snow into the weekend, a blast of warmth is due for much of the country east of the Rockies next week.
Warm air will once again surge eastward from the Plains to the East Coast this weekend and early next week. A strong storm next Tuesday and Wednesday will then be followed by colder air later next week.