There is a chance for an isolated shower Tuesday evening but more substantial storms are predicted for Wednesday afternoon and evening, the National Weather Service warned.

"Strong to severe thunderstorms and heavy downpours are possible as a cold front passes through the region Wednesday afternoon into early Thursday morning," the weather service said in a Tuesday evening briefing.

Flash flooding is not predicted for Long Island, although it is a possibility for points west, the briefing said.

Downpours may last into Thursday and Friday — the odds of rain are 50% and 30%, respectively — before an at least partly sunny weekend, the weather service said.

Daytime temperatures all week will reach the upper 70s, hitting 80 degrees on Sunday, with nighttime lows descending into the mid-60s.

Friday’s weather appears "unsettled," the weather service said, partly because a rain-causing low pressure system may develop off the southeast coast and potentially mesh with the remnants of Tropical Storm Nicholas, which was about 30 miles south-southwest of Houston at 5 a.m. Tuesday.

While no longer a hurricane, Nicholas is deluging the Gulf Coast, with some areas expected to get 20 inches of rain, and life-threatening flash floods could threaten much of the Deep South for the next two days, the National Hurricane Center said.

Saturday on Long Island should be the first day of a three-day sunny stretch, as a cloud-clearing high pressure system could develop. And as soon as Sunday, the weather service said, "a slightly cooler and drier air mass (is forecast) to enter the northeast."

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