A massive low pressure system moving in from the west dumped 3 to 4 inches of rain across parts of the Lower Hudson Valley, northeast New Jersey and southern Connecticut Thursday, but mostly spared Long Island.

But Joey Picca, a National Weather Service meteorologist in Upton, warned that overnight rains here could turn heavy in time for the Friday morning commute, as the system hits Nassau and makes its way east, possibly bringing thunderstorms.

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"It's a pretty stout storm system," said Pica. He said the most severe weather should arrive on Long Island between 5 a.m. and 8 a.m. Friday.

Clearer skies and drier weather aren't expected until Sunday.

New York City's Central Park recorded 1.81 inches of rainfall Thursday. A flash flood warning is in effect until 10:45 p.m. for parts of Connecticut, New Jersey and the Lower Hudson Valley because of heavier rain there.