An intense storm system is moving north into Massachusetts after causing major flooding in Connecticut and New York.

The National Weather Service reported that more than 13 inches of rain fell in Islip, N.Y., where the mayor says flooding is worse than occurred after Hurricane Sandy.

The National Weather Service office in Taunton has posted a flash flood watch for Middlesex County until 8 p.m. Wednesday. It says the storm has produced 1 to 2 inches per hour, with reports of up to 3 inches per hour. It advises that drivers avoid roads that appear flooded.

In an advisory just after noon, the service said it expected gusty winds to result in a few downed tree limbs and isolated power outages, based on winds expected to gust to up to 40 mph.