As a new area of low pressure slowly tracks east from the Central Plains, storms will be riding along its extensive cold front draped from the Plains through the Northeast. This will make for a sharp temperature contrast, but will also aid in a flood threat due to heavy, training thunderstorms.
This warm front will be responsible for several severe storms on Saturday, particularly for areas south of the front. That’s the region in the warm sector of the storm where temperatures will be in the 70s and 80s along with higher levels of humidity. To the north of there, in cities like New York and Boston, it may be too cool for thunderstorms.
In terms of timing, the radar will have a messy look to it. Instead of a strong line of thunderstorms, we’re expecting there to be rounds of strong to severe thunderstorms. So during the morning hours, there will be rounds of showers and storms tracking eastward through the eastern Great Lakes, the northern Mid-Atlantic, and the southern and central New England regions. Most of these storms will be sub-severe due to the low levels of instability at the start of the day.
The atmosphere will become more favorable in the afternoon. Showers and thunderstorms will organize in the western Great Lakes region, around in the greater Chicago area. We’ll also see a line of thunderstorms working southeastward, spanning from western New York through northern Ohio midday. Then as we get toward the evening, the storms will slowly move to the south toward the Mason-Dixon Line. Meanwhile in the Ohio River Valley, there will be hit or miss storms. These storms may then organize into a large batch of rain and thunderstorms overnight in the northern-Mid-Atlantic region and into southern New England. Thunderstorms will also continue to track through the south Great Lakes region overnight, moving from Chicago to Detroit to Cleveland, or nearby areas.
Damaging winds and moderately-sized hail will be the main threats, but an isolated tornado cannot be ruled out with any of these thunderstorms Saturday into Saturday night.