Tuesday, 11:55 a.m.
One powerful storm left the playing field late yesterday and last night, finally pulling all of the precipitation away from the Northeast. Even as that was unfolding, another nasty storm was charging across the Plains into the Midwest, with a full-fledged blizzard raging across parts of North Dakota and northwestern Minnesota. Many locations piled up 6 to 12 inches of snow, with some between 12 and 18 inches - and that doesn't include the snow drifts that no doubt had to be several feet deep in some places because of the powdery snow being moved all over the place by winds gusting over 40 miles an hour at times.
This latest powerhouse is now crossing Lake Superior, and a chunk of arctic air is now driving across the Dakotas and the Midwest. It will turn colder across the Great Lakes, but the arctic air won't get much farther downstream tonight and tomorrow as the storm lifts out to the northeast into central Quebec and weakens.
With time, though, the area of high pressure over the Canada prairie provinces will be reinforced by another high building in from the Northwest Territories, and the renewed high will move eastward and send chillier air into the Northeast Thursday and Thursday night into Friday.
The impact of this bleeding of colder air from the north will be felt down into the mid-Atlantic states into Friday. As the next storm starts to evolve on the Plains tomorrow, it will spit out a wave of low pressure that will travel along the front separating some of the chilly air stretching from the northern Plains to New England from truly warm and increasingly humid air to the south. This wave will generate some rain and strong thunderstorms from central and northern Illinois eastward into Indiana, Ohio and part of Kentucky tomorrow afternoon and tomorrow night. This will then move through the eastern Ohio Valley and into the mid-Atlantic states Thursday before exiting off the mid-Atlantic coast. Colder will be drawn southward behind it, and that's very well illustrated in the 6z April 1 GFS ensemble 2-meter temperature anomalies for Friday:
Over the eastern Plains and Mississippi Valley, though, the weather will become very active late Thursday and Thursday night as the storm forming in the Plains begins to intensify and head toward Michigan. Look at the following images, starting with the 12z April 1 NAM 850mb forecast for 6z Friday:
Those are strong winds just off the deck blowing some really warm air up the Mississippi Valley. Here's the projected dew point temperatures:
These things combined with a plethora of severe weather parameters would strongly suggest it won't be a matter of IF there will be severe weather, but where it will be and how widespread it will get. Here's what the current thinking is here at AccuWeather.com:
As the storm pulls a cold front through the Ohio and Tennessee valleys into the Deep South on Friday, there will be SOME severe weather, but it will be past its peak, and there will be little severe weather east of the Appalachians. Behind the front, whatever warmth there is will be wiped out, so that most places from the Plains to the Appalachians will be below average Saturday, and other areas around the country won't be much above it.
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.