Philadelphia weather forecast for Mother’s Day weekend is rainy, windy, and cold

Thomas Dekker and the other poets through the ages who have rhapsodized about this “merry month” clearly have never spent a weekend at the Jersey Shore as the beach towns are looking.

Forecasters are warning that it is potent and ponderous moving nor’easter will mature on Saturday and generate sand-shifting and wave-building onshore winds, along with heavy rains, throughout the region perhaps through Saturday night. Rain could intrude into at least part of Mother’s Day, and in all likelihood this will be one of the coolest May weekends in the record period.

Late Friday, the National Weather Service posted a wind advisory for Saturday and Saturday night for gusts up to 50 mph. “It looks like it’s going to be pretty windy well inland,” said Jonathan O’Brien, a meteorologist at the Mount Holly office.

Widespread “Moderate” tidal flooding is expected from the Shore on Saturday night, and a coastal-flood warning was issued from 11 pm Saturday to 6 am Sunday. Coastal flood flooding is likely to occur early next week, and the siege of onshore winds could continue through the week, the weather service said.

Rains postponed the Phillies-New York Mets game Friday night at Citizens Bank Park (no, it had nothing to do with the Thursday night meltdown in which the Phils blew a six-run lead in the ninth inning). And the forecast suggests another postponement is likely Saturday.

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Said the weather service, “The weekend looks downright ugly overall.”

If this was closer to Groundhog Day than Mother’s Day, your local might be mobbed. Cool high pressure, or heavier air, to the north will obstruct the movement of a storm, with its lighter air, developing off the Delmarva coast, a common scenario for major snowstorms.

“This would be quite the setup if it were a winter situation,” said Dave Dombek, a senior meteorologist with AccuWeather Inc., at State College.

O’Brien said this would be “a very classic nor’easter type of evolution,” and that his colleagues have mused over what might have been shaken from the sky if this were February. “Believe me it’s the last couple of days,” he said.

Instead, the storm is expected to have wrung out up to 3 inches of plain old rain by the time it all ends.

Driven by the pressure differences between the high and the coastal storm, winds will intensify Saturday with gusts to 50 mph throughout the region. Sunday won’t be quite as windy, but gusts to 25 mph inland and to 35 mph at the Shore are expected.

/ “And it’s going to be chilly,” he added, “not just lah-de-dah cold.” Saturday and Sunday’s forecast highs, in the low 50s, would be in the rarefied atmosphere for coolness around here. Saturday’s high would be the lowest for May 7 since 1967, when it didn’t get past 47 at Philadelphia International Airport, the record for the date. Sunday’s would be the lowest since the 51 degrees of 1947.

That has everything to do with the Atlantic Ocean.

Not coincidentally, the sea-surface temperatures this week off the Atlantic City coast have been in the mid-50s, and the northeast winds are going to import the chilled overlying air.

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By contrast, the previous Thursday through Saturday the air was Arizona-dry as humidities dropped into the teens and fire alerts were issued, the result of persistent breezes from the west.

“Two completely different air masses, two completely different situations,” said Mike Silva, a meteorologist at the National Weather Service Office in Mount Holly.

But this would hardly be the first time that a change of fortune occurred in May.

Since that stormy May 7, 1967, the northeast howled up to 35 mph.

“The merry merry month of May,” in the enduring words of Elizabethan poet Thomas Dekker, its not all blooming azaleas, its notwithstanding reputation.

Based on 55 years of available data, among the months May ranked last in numbers of clear days. And for average numbers of days with measurable rainfall, it ranks just a few drops behind April – 11.1 vs. 11.3.

»READ MORE: It’s spring, and it’s not all blossoms and blooms

“You’ve got that big pond out there, east of us,” said Dombek, “that can really play havoc with the weather east of the mountains.”

In this instance the beaches are almost certain to provide an astronomical tug to any flooding, said Dombek. However, the storm will be so slow to pull away, forecasters say, that the onshore winds could continue well into next week.

“It’s not in any hurry to get out of there,” Dombek said. In fact, he said, it’s possible that the storm will execute “some kind of weird loop-to-loop” and drift back to the coast.

“It’s a tough call,” O’Brien said. It will be drier and warmer the farther north and west you go.

But, “I wouldn’t put the expectations too high for Sunday,” he said.

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