After awakening to spring-like weather Thursday, Pittsburghers were in for a second awakening -- a rude one -- that will be soaked with rain, chilled by a dive in the temperature and possibly coated with ice and/or snow.
Rain moved in during the balmy morning, causing the National Weather Service to post a flood advisory for Pittsburgh and Allegheny County, in effect from 1 a.m. Saturday to 10 p.m. Sunday.
As much as 1.5 to 3 inches of rain was expected to fall over the Monongahela, Youghiogheny and Cheat river basins.
The weather service said the rivers at the Point in Downtown Pittsburgh would pass the 18-foot threshold for Mon Wharf flooding on Saturday morning, eventually topping out just above 20 feet, which is enough to swamp parts of the North Shore Riverwalk.
That prompted the Public Parking Authority to close the wharf for parking today as a precaution. It will remain closed until further notice. The weather service said it didn't expect the river to recede until late Sunday.
As with last week's storm, Pittsburgh will spend time on the edge of freezing, creating uncertainty about what will fall and when. The weather service said most precipitation south of the city will be rain, while to the north it will be frozen. The likely transition from rain to something else is expected to come late this afternoon or early in the evening.
AccuWeather, based in State College, said 1 to 3 inches of snow would fall in Pittsburgh tonight after the changeover.
The weather service Thursday night posted a winter weather advisory for Allegheny and surrounding counties, with 1 to 3 inches of snow and sleet possible, from 7 a.m. today to midnight.
The weather service and AccuWeather forecasts call for a break in precipitation for much of Saturday, but much colder with a high in the low 30s. The rain-snow-sleet trio will perform again on Sunday.
The Thursday high temperature of 61 degrees in Pittsburgh was well above the normal high of 43 for the date but did not threaten the all-time record of 73 degrees set in 2001.
Jon Schmitz: firstname.lastname@example.org or 412-263-1868. Visit the PG's transportation blog, The Roundabout, at www.post-gazette.com/Roundabout. Twitter: @pgtraffic.
First Published December 5, 2013 7:11 AM