Wednesday, December 26, 2012

Sloppy Afternoon Begins

As of 1 PM the first fingers of today's storm are working north through the region, initially with snow falling in the northern and western suburbs, rain and sleet mixed in the city, and generally rain across South Jersey and the southern two-thirds of Delaware.  It's a pretty uneventful beginning to what will be a potent storm overall as low pressure transfers its energy from the Ohio Valley to the Atlantic Ocean and the secondary low intensifies later tonight.  That uneventfulness will change quickly for the city and northwest over the next few hours.

Temperature profiles across the region show that the freezing/nonfreezing line is generally across the city, with below 32 surface temperatures currently in the outer burbs and points north and west, while the city and points south and east are in the lower 30's or warmer.  AC was 42 at Noon, with warmer air poised to work in through the evening.

As expected, this storm is a rainmaker for South Jersey and most of Delaware, with the city getting that initial mixed bag that will gradually turn over to rain for all locations within the city. North and west still are in the running for a coating to two inches of snow up through the Quakertown-Pottstown corridor, with more snow and ice as one progresses northward into the Lehigh Valley.  Most of the computer modeling has backed off on the snow potential in the Poconos and has shifted more towards icy rain and sleet -- I'm not as sure this takes place given the cold temperatures in place up there.   One exception to this is the Euro, which is suggesting a healthy three inches or more north of Quakertown through the Allentown area as the afternoon and evening progress.  We will keep an eye on how the milder air aloft tries to surge in.

We predicted six to ten inches in general above Blue Mountain and we think most locations are still in line for that...although some valley spots in Central Pennsylvania might have to deal with icy rain and sleet in greater quantity than the mountainous areas do.

Route 202 near Route 322 in West Chester at 1 PM via PennDOT camera.

The farther north and west one is, the longer you will remain frozen.  The inner north and west suburbs (below Route 202)  probably will see snow and sleet in general for two to three more hours (until 4 PM or so), with the outer burbs above 202 holding frozen for an additional couple of hours after that.  The Lehigh Valley and Berks will transition to sleet and freezing rain after 6 PM but will be the last locations to warm above 32 and change to plain rain.

We'll provide another update later on.  You can also interact with us on Facebook and on Twitter.