The National Weather Service has now issued a hazardous weather outlook for a streaking, soaking possible nor'easter that could last from 12-18 hours on Mother's Day weekend in Pennsylvania.

The alert for the possible heavy, wind-driven rainstorm was issued for eastern Pennsylvania, but the entire state is supposed to be impacted. The storm is expected to form and move like a nor'easter, providing several inches of rain, wind gusts of up to 30 mph and possible flooding, according to the National Weather Service.                     

Here are a few more details on the storm:

  • Areas near rivers and streams could be susceptible to flooding. "Outdoor plans on Saturday will likely be a disappointment," said Mitchell Gaines, an NWS meteorologist.
  • The rain is expected to start on Friday night and stop by Sunday morning, so most of Mother's Day should be clear.
  • But on Saturday, the winds could be strong enough to cause tree and power line damage and sporadic power outages.
  • As much as 1 to 3 inches of rain can fall along the coast by the end of the weekend, with locally higher amounts possible, according to AccuWeather.
  • Heavy rain will overtake eastern Pennsylvania, New Jersey, New York City and Long Island on Saturday, before shifting northeastward to Boston and Portland, Maine, on Saturday night, according to AccuWeather.
        

AccuWeather said the possible nor'easter will move from the South, where it's expected to start as a damaging wind and thunderstorm. By the time it gets to Pennsylvania, however, it's expected to be less powerful, Gaines said.

The fact that it is expected to move from the South, and along the coastline, would make it a nor'easter, he said. "The low-pressure system that will be moving up the coast, and there will be quite a bit of rain," said Gaines said.

The storm already is causing severe weather across the South Central states and will gather strength, moisture, and wind in New Jersey and Pennsylvania this weekend, according to AccuWeather.

“As this storm moves offshore this weekend, additional energy diving southward out of eastern Canada will cause the storm to intensify,” AccuWeather Meteorologist Ryan Adamson said in an AccuWeather release.

The second wave of blustery showers will drop southward from Canada on the back edge of the storm into the mid-Atlantic and New York on Mother’s Day. It will take until later Monday before the dreary conditions fully exit New England, according to AccuWeather.

Water from the Atlantic will be pushed toward the upper mid-Atlantic and New England coasts due to the winds. The greatest threat for coastal flooding at times of high tide and beach erosion will be from the Delmarva Peninsula to Maine, according to AccuWeather.

“At this time, any coastal flooding looks to be minor since the storm will not be extremely strong and the full moon occurred this past Wednesday,” Adamson said.

Temperatures will be in the 50s.

Here is the forecast:

  • Thursday: Increasing clouds, with a high near 64. East wind around 9 mph.
  • Thursday night: Mostly cloudy, with a low around 44. Calm wind becoming east 5 to 7 mph after midnight.
  • Friday: A slight chance of showers. Mostly cloudy, with a high near 57. East wind 8 to 10 mph. Chance of precipitation is 20 percent.
  • Friday night: Rain likely, mainly after midnight. Cloudy, with a low around 48. East wind 8 to 10 mph. Chance of precipitation is 70 percent. New precipitation amounts between a tenth and quarter of an inch possible.
  • Saturday: Rain. The rain could be heavy at times. High near 57. Breezy, with an east wind 14 to 20 mph. Chance of precipitation is 100%. New precipitation amounts between 1 and 2 inches possible.
  • Saturday night: Rain. Low around 48. Chance of precipitation is 90 percent. New precipitation amounts between a half and three-quarters of an inch possible.
  • Sunday: A chance of showers. Partly sunny, with a high near 66. Chance of precipitation is 50%.