This was not supposed to happen so early in the season — and almost never had before.

And the sheer rarity of the snowstorm that ambushed the region on Thursday with eight-plus inches of snow in some areas likely was a factor in the ensuing mayhem that resulted in hundreds of traffic accidents, gridlock on suddenly snow-and-ice-covered roads, nightmare commutes, at least one death, and a storm of finger-pointing.

In the slushy aftermath after a night of cold rain and winds gusting past 35 mph, mass transit delays persisted on Friday; Regional Rail's Paoli-Thorndale Line was still shut down in the morning. Some schools in the suburbs decided to close for the day, others opted for late openings.

The 3.6 inches measured officially at Philadelphia International Airport not only was a record for a Nov. 15 for Philadelphia, it was the biggest snowfall so early in what we would loosely call "the season" in 65 years. It also qualifies as the No. 2 snowfall so early in the season in the entire period of official Philadelphia snow records, dating back to 1884.

If you're wondering why it was so hard to shovel, after sponging up that sleet and rain it weighed the equivalent of about 15 inches of snow.

The biggest problem Thursday was that the bulk of the snow came in a hurry — between 11 a.m. and 2 p.m. in the immediate Philadelphia area — and meteorologists acknowledged that they had to play catch-up with their forecasts. The National Weather Service in Mount Holly had issued a "winter weather advisory" in the morning, but its forecast called for an inch or less. It wasn't bumped up until after the snow was a fait accompli.

But Gary Szatkowski, the former head of the Mount Holly office, took exception to New Jersey Gov. Murphy's comments on Friday at a news conference that "I'm not going to let the forecasters off the hook, let there be no doubt about it."

Firing back on Twitter, Szatkowki, who lives in the Garden State, said: "My governor is doubling down on stupid."

A request for comment from the weather service offices that serve New Jersey — Mount Holly and Upton, N.Y. — was referred to headquarters. While not responding directly to Murphy, weather service spokesperson Susan Buchanan said: "This early season snowstorm challenged forecasters and numerical weather models. … We continue to assess our forecasts and related services for these rare events."

As to why road crews  did not treat highways more aggressively on Thursday, PennDot spokesman Brad Rudolph blamed the outbreak of early dismissals of schools, offices, and businesses, resulting in crashes and disabled vehicles that obstructed salt and plow trucks. With such traffic, he said, "it takes four times as long to get around."

As others did, he also faulted the forecasts, saying that if they had nailed it in the morning, more people would have stayed home.

"Had things been closed," Rudolph said, "that would have been very nice."

If it's any consolation, it was far worse to the north, upstate and in North Jersey, where a middle school in West Orange hosted a massive sleep-over for 300 students.

Hundreds of people spent the night stuck in their vehicles on I-78 near Allentown after accidents and snow made the roadway impassable.

But it was plenty bad in the Philadelphia region.

Chester County alone reported 350 disabled vehicles and 250 accidents. The storm was implicated in at least one fatality. Michael Robinson, 52, of Mullica Hill, was killed in a crash with a pickup truck about 6:15 p.m. Thursday in Mantua Township, Gloucester County, and authorities say poor road conditions likely led to the crash.

Meanwhile, SEPTA was dealing with slippery rails and problems with switches and signal equipment, some of which is old and particularly susceptible to weather, said Andrew Busch, a SEPTA spokesman. SEPTA suspended the Chestnut Hill West, Media/Elwyn, and Wilmington/Newark Lines, and the Paoli-Thorndale Line had to  shut down because  a large tree fell across its path.

The canceled lines drew crews away from lines that were operating, leading to a cascade of delays that left many passengers waiting for an hour or more on some lines.

SEPTA canceled service on three bus routes that all encounter narrow streets that are difficult to navigate in snow: Route 35, which serves Manayunk and is also vulnerable to snow due to Manayunk's hills; Route 48, which runs from Market and Front Streets to 27th Street and Allegheny Avenue, and Route 92, which runs between Exton and King of Prussia. Furthermore, Routes 9, 27 and 65 didn't go north of the Wissahickon Transportation Center due to ice.

Busch said that while SEPTA had been prepared for the storm, like everyone else it was surprised by the intensity, something more appropriate for late winter or early spring.

And while snow is fairly common when temperatures are near or above freezing in late March and April, when the upper air, where the snow is made, is cold, that is not usually the case in mid-November.

One reason why big snows are scarce this early is the Atlantic Ocean. Most of the major snowfalls around here are the product of coastal nor'easters, which generate strong onshore winds. They are prodigious importers of mild air; this time of year, sea surface temperatures on average are in the 50s.

The key on Thursday was just how cold and dry the air near the surface was, said Dan Pydynowski, a meteorologist with AccuWeather Inc. At the onset, the precipitation was intense, and the cold air held its ground long enough for several inches of snow to accumulate.

A side issue to consider is where the snow is measured. Philadelphia's official measuring spot is at the airport, which is next to the river, near a swamp, and in proximity of buildings and paved surfaces.

It is not the most representative venue for measuring snow; snow is far more likely to accumulate early or late in the season in elevated areas and places away from the peak influences of the urban heat island effect.

A 13-year-old weather geek named Joel N. Myers, who would go on to found AccuWeather, recalled measuring 13 inches at an intersection in Northeast Philly on Nov. 7, 1953, and being outraged when he learned of the official total, 8.8 inches.

That official total came from the airport.

It will be quite chilly for the next several days, with December-like daytime temperatures in the 40s and nights near freezing, but no snow will be measured at the airport or anywhere else. Forecasters promise.