Downpours, Storms Continue for New England Today

Today will be the most active and wettest day across the region during this stretch. A more organized trough will move through the region with the surface boundary remaining south of New England. At the same time, a surface low pressure system will glance the region, lifting north and west of New England into Quebec. This setup will provide stronger forcing for more numerous showers and storms through the day.

A slug of steadier rain with embedded downpours will continue to move across southern New England (and southern New Hampshire) this morning. This slug of rain will begin to move offshore by this afternoon. Embedded downpours have been common within this band of rainfall.

A narrow band of 2-4 inches of rain has fallen just south of Boston, prompting a flash flood warning, which is currently in effect through 11:15am. The National Weather Service has upgraded the warning to a "considerable" threat. This warning is focused just south of Boston, near the Quincy area. Portions of Interstate 93 are closed and cars are reported to be stuck.

Flooding on Interstate 93 near Boston. Photo by NBC Boston

A stalled frontal boundary with tropical moisture being pumped into the region from a former tropical storm is a perfect setup for something like this to happen, as we've been writing about all week. Multiple streets have been flooded and are impassable this morning in cities across Norfolk County. A flood watch remains in effect through this afternoon for much of eastern Massachusetts and Rhode Island.

In the afternoon, a line of scattered showers and storms will likely develop across western New England and try to slide eastward into the evening. Once these storms hit the more stable marine air over eastern New England, they will likely weaken and fall apart rather quickly. Some strong to severe storms will be possible, with the highest risk across Vermont. Some instability and modest shear look to combine with continued higher moisture and stronger lift to bring the ingredients for severe storms together.

With that said, questions about overall coverage of storms and a weak cold pool may be rather significant limiting factors. At this time, the setup looks to support more by way of isolated severe storms rather than widespread. Storms will likely be most numerous across Vermont and northern New Hampshire, with more isolated activity elsewhere. The more stable marine air being blown over eastern New England on Thursday along with an overall lack of daytime heating and instability means the afternoon storm threat is much more muted moving east of the Connecticut River.

With a generally uncapped atmosphere across western New England (mainly Vermont), storms will likely begin to fire up by midday or the early afternoon hours. Storms will likely continue to fire throughout the afternoon and evening across Vermont, northern New Hampshire and potentially interior Maine. Storms should begin to gradually diminish as the evening wears on.

Moisture content within the atmosphere remains highly elevated, with precipitable water values (a measure of water vapor in the atmosphere that could become precipitation) remaining well over an inch region-wide. This indicates a moisture-rich atmosphere that will be capable of producing heavy downpours and localized flash flooding. Should multiple storms move over the same area this afternoon, flooding similar to what has been seen south of Boston this morning could develop.

Below: HRRR showing potential weather this afternoon:

Heading into this weekend and next week, a warming trend is likely with widespread 80s returning to areas that will be kept cooler over the next couple days. Overall, a pretty typical summer pattern is on tap with the scattered storms and seasonable temperatures away from the coast over the next couple days. This weekend is shaping up to be a very nice July weekend. The extent of a warm-up next week will hinge on the timing of potential unsettled weather.