Tropical Storm Bonnie weakened and then made landfall near Charleston, South Carolina early Sunday morning. The biggest issue with this storm is heavy rain, which is impacting the Southeast United States this weekend. Some of the tropical moisture wil migrate up into New England by Monday.
The first batch of showers and downpours will be sporadic and spread in with very muggy air Sunday night.
During the morning hours on Memorial Day, periods of showers and downpours will be most widespread in Southern New England. This will very likely impact many ceremonies and parades. The north and west of Boston, rain will be less widespread and many will be dry. Clouds will be stubborn throughout.
Because it will be so humid, these will be the type of downpours that put down a lot of water in a short period of time. There could be some areas of street flooding that develop in a few spots.
By afternoon many of the showers and downpours will shift out, allowing for some dry hours in Southern New England. So while we'll still have lots of clouds and muggy air to contend with, the odds of having a dry cook-out or parade are highest after lunch. North and west of Boston we'll keep an eye out for a broken line of thunderstorms that will likely develop during the afternoon, particularly in parts of Vermont and New Hampshire.
A widespread 0.25-0.75" is likely from this rain, with some areas picking up 1" or more due to repeated downpours.
Any lingering clouds or showers early Tuesday will then give way to more sun and less humid air by afternoon as all of this moisture is pushed offshore by an approaching cold front.