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A weather condition consisting of drizzle, light rain or snow, amounting to minimal measurable precipitation accumulation in a 24 hour time period <.1".

Used primarily by those visiting Pittsburgh during traditional collegiate school sessions - September - May, as this is the predominant weather pattern for those months.
Joe: Hey Tim how's the weather today.
Tim: It's Pittsburghing.
Joe: I wish it would either rain or not, the constant Pittsburghing is dreary.
by FPB February 04, 2013