Signals are increasing for a new round of severe weather in parts of the Northeast Wednesday. This comes as a shortwave trough tracks in a northeastern direction from the central US, beginning to transition from a neutral to positively-tilted phase.
The model guidance continues to suggest at least a somewhat favorable environment for severe weather, especially Wednesday afternoon and Wednesday night. One of the main features is a moderately strong low-to-mid-level jet span from the Carolinas up through much of New England. That wind energy paired with instability will allow for the development of thunderstorms.
Instability varies based on model guidance, thus highlighting the uncertainty still present in this forecast. This is likely due to how widespread the rain and storms Tuesday night into Wednesday morning will be. That, in addition to the cloud cover, can hamper the formation of thunderstorms in the afternoon. At this time, the best instability looks to be in and near the I-95 corridor, with values nearing 3000 J/kg.
It’s still early to know how exactly storms will play out on Wednesday but we are currently thinking that there will be several supercell thunderstorms that develop in the afternoon across western and central New York down through northern Virginia. After a few hours, those storms should then evolve into a linear line of convection, affecting areas to the east in this same region overnight Wednesday. Damaging winds and a spin-up tornado are the main threats these storms may pose. Elsewhere, there will be a few spotty storms in the Northeast. but the main activity looks to be in the morning with numerous showers around.
Another risk associated with these storms and really any of the rain that falls this week is the heavy precipitation, which may trigger flash flooding. This comes as a similar weather pattern develops by midweek, allowing for ample moisture to stream up the East Coast from the Gulf of Mexico.