From the National Weather Service:
Special Weather Statement National Weather Service Boston/Norton MA 413 AM EDT Thu May 30 2019 ...HEAVY RAIN AND ISOLATED FLOODING POSSIBLE THIS EVENING AND OVERNIGHT... Rain will overspread Massachusetts, Rhode Island and Connecticut between 8 pm and 11 pm this evening from west to east and then continue overnight. Bands of heavy rain are possible with rainfall totals of one to two inches possible over a short period of time. If this occurs there will be low a risk of isolated urban/poor drainage flooding. There is also uncertainty on the exact location of heavy rain, ranging from the south coast of Massachusetts and Rhode Island northward to the Massachusetts turnpike. Less rainfall and little to no flooding is also possible. Given forecast uncertainty stay tuned to later forecasts on this developing weather system.