From the National Weather Service Boston:
A cold front moving through New England Thursday night will draw upon tropical moisture from Michael, creating local downpours. Michael or its remnants will then pass south of New England on Friday. Here is a brief outline:
Heavy Rain Threat:
Pockets of heavy rain are possible Thursday into Thursday evening and this may result in a low risk of isolated flash flooding.
This threat remains localized and it is quite uncertain if and where this will materialize.
The threat for heavy rain and the low threat for flash flooding threat will come to an end by early Friday across most of the region. The exception will be the far southeast New England coast, especially Nantucket where heavy rain from Michael may impact the region depending on how close the storm tracks to southern New England.
A MARGINAL RISK for excessive rainfall and the potential for flash flooding has been issued for Thursday by the folks NOAA NWS Weather Prediction Center.
Damaging wind gusts are not expected across most if not all of the region.
There is a low risk for a period of 40 to 50 mph wind gusts across the Cape/Islands Thursday night into Friday night that may result in minor tree damage/isolated power outages.
A period of north to northwest gale force wind gusts are possible Thursday night into Friday night for our southern waters, particularly south of the outer-Islands.
Seas of 7 to 11 feet are possible Thursday night through Friday night across our southern outer-waters.