Saturday night into Sunday night...
A progressive upper level trough moves from the Ohio Valley
Saturday evening to off the Massachusetts coast Sunday evening.
It surface low pressure reflection is forecast to move from the
Mid- Atlantic coast northeastward to near or just south of
Nantucket. There still remains some model differences, but all
models spread rain from SW to NE across the region Saturday
night, mainly after midnight. Rain should continue much of the
day on Sunday, with the steadiest in the southeastern half of
southern New England. Looks like 0.25 to 0.75 inches of rain is
possible... with 1 inch not out of the question in southeast
areas, closer to the low track. Clouds, precipitation, and
onshore flow will keep high temperatures in the 50s.