As John Bolaris mentioned in his philly.com post, a nor'easter could affect the region next week, and, yes, it's that time of year.

Right now the computer models are all over the place, which is understandable given the complexities and the potential scenarios.

Cold rain is possible on Tuesday, and if the storm bombs out of the coast, some snow could wrap in at the end.

Parts of the region already have received measureable snow, as much as 3 and 4 inches, but officially Philly hasn't had anything more than a trace yet.

Thus, in the off-chance that Philadelphia receives anything measureable next week – that's 0.1 inches or more – it would be the city's first of the season, and come right about on schedule.

In the 130 years of snow records, the average date of the first official measurable snow in Philly is Dec. 11.

This has been a highly moveable feast, varying from year to year, and with tremendous decadal variability.

In the 1980s, for example, the average start date was Dec. 3; in the 1990s, Jan. 5. Our only explanation would be that the atmosphere is capricious -- and snow, more capricious.

Philadelphia has had some memorable first snows.

Recall that last year, it came in ambush on Dec. 8 while the Philadelphia Eagles were hosting the Detroit Lions. Thus Football Nation had the opportunity to witness a major forecast slip-up.

The first snow of 2009 didn't arrive until Dec. 19 – that day, 22.5 inches was measured officially at Philadelphia International Airport/National Park.