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Philly is forecast to have 4 consecutive clear days for the first time in almost 2 years

No one ever called Pennsylvania "The Sunshine State," and Philly is among the gloomier places in the national database, but expect wall-to-wall sun for at least the next four days.

A view from the South Street bridge looking north of the Philadelphia skyline, Schuylkill River, Schuylkill Expressway, Schuylkill River Trail and FMC Building last month. This isn't "The Sunshine State" but we're in for a run of splendid days.
A view from the South Street bridge looking north of the Philadelphia skyline, Schuylkill River, Schuylkill Expressway, Schuylkill River Trail and FMC Building last month. This isn't "The Sunshine State" but we're in for a run of splendid days.Read moreElizabeth Robertson / Staff Photographer

The National Weather Service has no fewer than 40 varieties of advisories, warnings, and watches to alert the citizenry of what’s coming, but the agency has nothing that describes what we are about to experience for the next several days.

For Wednesday through Saturday, the forecast is calling for four consecutive, brilliantly clear days — defined as days when the skies are 30% or less cloud-covered — and the streak might go on “even longer,” said Carl Erickson, a meteorologist with AccuWeather Inc.

Statistically, Philadelphia is among the nation’s gloomier locations, according to the National Center for Environmental Information, and the city hasn’t had four straight clear days since November 2020. Highs are expected to range from 77 to 82 degrees, with fall-like cool nights: The forecast low for Thursday morning, 53 degrees, would be the chilliest reading since May 10.

» READ MORE: Philly's summer of 2022 in five charts

And the skies will be well-scrubbed by an air mass that is routing the atmospheric muck and mugginess, ideal for night-sky watchers toward the weekend as the waning moon comes up later and later, not rising until 11:21 p.m. Saturday.

In short, it appears that the region is in for an anomalously splendid run of weather, worth savoring, said Ray Martin, a lead meteorologist at the National Weather Service Office in Mount Holly.

We’re not quite used to this

No one ever called Pennsylvania the Sunshine State.

And although Philadelphia isn’t quite as sun-challenged as Pittsburgh, according to the environmental center, for cloud traffic it is very much in a congested area. That’s life among so much water and storm traffic.

Sunshine, and lack thereof

The National Center for Environmental Information calculates how much sunshine locations could potentially get in a year, based on sunrise and sunset times. Here are some places that get the most, and least, amount of sunshine possible.

  • Yuma, Ariz.: 90%
  • Las Vegas: 85%
  • El Paso, Texas: 84%
  • Pittsburgh: 46%
  • Syracuse, N.Y.: 45%
  • Juneau, Alaska: 30%
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On average, Philly receives 56% of all possible sunshine annually, the center says, which places it near the bottom 25% of the stations in the national database.

You want nonstop sun? Try Yuma, Ariz., which checks in at 90% of possible sunshine, with 247 clear days (maybe 248 in leap years).

In Philly, on average we can expect 93 of those a year. It could be worse. It is elsewhere. Buffalo, N.Y., averages 58 clear days; Detroit, 75; and St. Paul Island, Alaska, 18.

» READ MORE: Recent rains have eased rain deficits in the region.

But we are entering the climatological peak period for clear days around here, with October and September ranking Nos. 1 and 2 among the months. Summery showers become scarce and the more organized cool-season storms are still waiting their turn.

A high time

The precipitation probability is absolutely zero through Sunday because high pressure is forecast to dominate much of the East. Just what is “high pressure”?

While barometric pressure readings have pretty much vanished from weather forecasts and public consciousness these days, they represent a critical weather variable.

Pressure is simply the weight of the air. When the pressure is high, the air is heavy, and the weather tends to be fair as descending currents discourage clouds. Contrary to popular perception, the air actually is likely to be lighter during a storm, symptomatic of rising air parcels that condense into rain and snow.

» READ MORE: Barometric pressure could be affecting your joints

The very concept that air had weight eluded the great minds of scientific history, including Galileo’s. The insight is credited to his countryman, physicist and mathematician Evangelista Torricelli, who famously wrote, “We live submerged at the bottom of an ocean of the element air.”

Evidently not a bad situation to be in around here for the next several days.