Nasty Northern U.S. Severe Weather Outbreak Continues Today, Tuesday.

Tornado near Ludlow, South Dakota Sunday
from @SeanSchoferTVN via Twitter.  

A vigorous weather disturbance is moving generally west to east across the northern United States, and it's leaving a trail of severe storms and tornadoes with it.

Yesterday, Montana, the Dakotas and Nebraska suffered through it. There were unconfirmed reports of some tornadoes with supercells, but the big story was wind and hail.

Hail bigger than softballs plunged through house roofs in parts of Nebraska, and winds gusted to more than 80 mph in storms in parts of Montana and North Dakota.

These same areas were pummeled by storms Saturday, too.

The round of storms managed to hold much of their punch overnight, and before dawn, severe thunderstorm watches and warnings were up in much of South Dakota. This storm system is so strong that thunderstorms don't seem to weaken as much as they usually do in the predawn hours.

As of 5 a.m. local time Monday, Sioux Falls, South Dakota was reporting a thunderstorm with winds gusting to 62 mph.

The heat of the strong June sun tends to encourage updrafts that create stronger storms, so storms usually reach their peak intensity in the late afternoons and evenings. This trend will continue with the current storm outbreak as it travels east.

However, as I've already said, those in the path of this cold front can expect at least some severe storms in the late night and early morning hours, when severe weather is usually less likely.

This afternoon, it looks like the timing is such that the disturbance will be in Wisconsin, Michigan and northern Illinois. With the heating of the day, intense storms will fire up in these areas again.

All kinds of threats are possible with this batch of storms, including a few tornadoes. Most of the havoc will be caused by hail, very strong winds and local flash flooding from today's storms in the Great Lakes region.

Keep an eye to the skies there.

Overnight, the storms will crash into southern Ontario, and on into New York and Pennsylvania, and maybe into western New England, places like Vermont late at night.

The storms might weaken some with the loss of daytime heating, but overnight severe weather with strong winds and hail remains possible, given the strength of the eastward moving storm system.

It's been so wet in northern New York, Vermont and New Hampshire. If no more rain falls this month, Burlington, Vermont will still have its sixth wettest June on record, with more than seven inches of rain so far.

Heavy downpours with some of these storms could cause some local flash flooding in the region. That's not a super high possibility, but it's something to watch out for.

Jet stream level winds are also stronger than normal for this time of year, and that will also help encourage severe weather.

Tuesday afternoon, it's the Northeast's turn for severe weather. The biggest threat will depend upon where the best instability and the strongest upper level winds set up during the peak of the sun's heating in the late afternoon and evening.

It also depends upon where and when a subtle line of lower pressure sets up ahead of the cold front by afternoon. It's near this so-called "trough line" where the worst storms will probably fire up

My guess, and the location might shift some, is the highest chance of severe thunderstorm winds, large hail, and even a tornado or two, is interior southern New England, the Hudson Valley of New York, eastern Pennsylvania and New Jersey.

So from the eastern Dakotas this morning on into the Great Lakes today, and on into the Northeast Tuesday, watch the skies and take shelter if storms threaten. Some of these could be really nasty.