Long Island Memorial Day Weather Forecast Takes Turn For The Worse

Let's put it this way: If you have outdoor plans for Memorial Day Monday and there's any way you can move those plans to Sunday, you are going to want to go ahead and do so.

The National Weather Service has issued a hazardous weather outlook for Long Island, warning of the chance of localized flash flooding Sunday night through Monday as an approaching cold front interacts with moisture associated with Tropical Storm Bonnie.

There will be a chance of showers and thunderstorms Sunday night, but it's Monday when the island will get a good soaking. There's a decent chance it will be raining non-stop from early Monday morning until 6-7 p.m., according to the latest NWS forecast.

"The confidence at this time of where exactly the heavy rain occurs is low so chance for flooding is at this time around 30 percent," the NWS said in a forecast discussion Saturday evening.

Tropical Storm Bonnie is expected to make landfall around the coast of South Carolina on Sunday, according to Weather.com.

"It does appear a system moving across the Northeast on Memorial Day will tap into some tropical moisture and pull it northward," AccuWeather meteorologist Dan Pydynowski said.

Sunday is expected to be much like Saturday on Long Island: Sunny with a high near 80.

The mercury hit 79 at MacArthur and JFK airports on Saturday, but at LaGuardia Airport, the temperature tied a daily record high of 92 degrees. And at Newark Liberty International Airport, it was a scorching 96 degrees.

"Thanks to the sea breeze, there was a 17 degree difference within 20 miles," the National Weather Service's New York office posted on its Facebook page. "That's almost a 1 degree drop per mile (0.85 degrees for those wanting to be more precise)!"

If you're heading to the beach Sunday, there will be a moderate risk of rip currents at Atlantic beaches. The NWS urges beach-goers to swim only in lifeguarded areas.

Here's the full forecast:

Sunday- A slight chance of showers and thunderstorms after 3pm. Sunny, with a high near 80. South wind 7 to 13 mph. Chance of precipitation is 20%.

Sunday Night- A chance of showers and thunderstorms, then showers and possibly a thunderstorm after 3am. Some of the storms could produce heavy rainfall. Patchy fog after 11pm. Low around 66. South wind 7 to 13 mph. Chance of precipitation is 80%. New rainfall amounts between a quarter and half of an inch possible.

Monday- Showers and possibly a thunderstorm. Some of the storms could produce heavy rainfall. Patchy fog. High near 75. South wind around 8 mph. Chance of precipitation is 90%. New rainfall amounts between three quarters and one inch possible.

Monday Night- Showers likely, mainly before 7pm. Mostly cloudy, with a low around 63. South wind 5 to 7 mph. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

Tuesday- Mostly sunny, with a high near 80.

Photo: AccuWeather