Rain, Snow, Sleet On Saturday: Hudson Valley Forecast

HUDSON VALLEY, NY — A prolonged, heavy rainfall that could drop up to 3.5 inches on the region is expected to start overnight — and in the mid-Hudson, it'll probably start as snow, forecasters are warning.

Due to the weather, Yonkers has postponed its St. Patrick's Parade.

Dutchess, Orange, Putnam, Rockland and Westchester counties are under flood watches.

Western Ulster County is under a winter weather advisory, as snow accumulations of up to two inches and ice accumulations of up to one tenth of an inch are possible. Precipitation will initially spread from west to east as snow, before transitioning to a wintry mix of rain, freezing rain, sleet, and snow, and ultimately to all rain. Sheltered valleys may see a later transition to rain and higher accumulations of ice and snow, the NWS said.

The National Weather Service also issued a hazardous outlook for Dutchess, as the storm could first dump light accumulations of wet snow, sleet and rain Friday evening east of the Hudson, plus switch back to flurries as it departs late Saturday.

"Watch for slippery travel wherever wintry precipitation occurs," Bruce Furbeck of First Due Weather said on Facebook. "There is potential for at least a glaze of freezing rain in western Orange County from about I 84 northwestward, this evening and overnight."

The potential for flooding could linger into late Saturday night, the National Weather Service said. Minor flooding is likely along some quick responding small rivers and streams, particularly across Rockland and Westchester counties and northeastern New Jersey.

The service classified the threat for the Bronx River, Sprain Brook, Saw Mill River, Hutchinson and Mamaroneck Rivers in Westchester County, and Ramapo and Hackensack Rivers in Rockland, at "medium" — meaning roads could be inundated but there would be minimal or no property damage.

The heavy rain will last for 6 to 8 hours from late Saturday morning into the afternoon, the NWS said.

"The afternoon looks very soggy, with periods of rain and temperatures in the low to mid 40s," Bill Potter of Hudson Valley Weather said on Facebook. "Unfortunately, our snow lovers will be left out in the cold rain once again ... a common theme this winter."

Long Island should receive the brunt of the storm, including beach flooding and scattered dune erosion possible during times of high tide.

Also, heavy rain and/or runoff during the time of high tides Saturday could cause localized flash flooding of coastal and tidally affected roadways and properties along the Sound Shore.

It's all coming from a storm system expected to spread across the Carolina coast to the Northeast urban corridor. The NWS issued a Slight Risk of Excessive Rainfall leading to Flash Flooding from southern Maryland into Boston's metro area.

Some flights could be cancelled or delayed on the East Coast; however, the quick-hitting nature of the storm will allow for a return of dry weather and sunshine by Sunday, said Renee Duff, AccuWeather meteorologist.

Here's an hourly look at the next 48 hours based on Dutchess County: