In what the National Weather Service calls "a one-two punch," a snowstorm that turned to rain overnight will change back to snow Wednesday night and could bring up to 8 inches of the unwelcome powder for Thursday morning's commute.

The service has issued a winter weather advisory in effect on Tuesday until midnight, and a winter storm watch, in effect Wednesday evening into Thursday evening.

About 1 to 2 inches of snow, slightly less than the 2 to 3 inches predicted in an earlier forecast, came in a "quick burst" of snow Tuesday night.

But weather service meteorologist Joe Pollina said around 9 p.m. that the transition was ongoing.

"We're getting reports now of a changeover to a wintry mix, with some sleet and freezing rain across the area, and probably some rain in some areas," Pollina said.

As temperatures rise overnight, periods of rain were expected and highs Wednesday were expected to be in the 40s.

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Wednesday morning, Long Island commuters will be facing wet, slushy conditions, said weather service meteorologist Jay Engle, with the possibility of ponding on roads and minor flooding.

But Wednesday evening through Thursday evening, the process reverses and the rain is expected to turn back to sleet, then to between 4 and 8 inches of heavy snow, the weather service said.

The prospects for the Thursday morning commute? "Potential high impact," the weather service said in a Tuesday weather briefing.