Thursday, 10:50 p.m. update

Computer models just starting to come in are indicating a significant winter storm will arrive by noon Saturday.

One model coming in now is much more robust with precipitation amounts and colder temperatures, which would translate to more snow and ice before a complete changeover to rain here in the city and surrounding suburbs.

I'm still waiting on more reliable computer guidance to come out, which would either verify or override this particular model, which in the past has not handled winter storms well.

Timing is still the same: snow arriving around noon on Saturday and quickly spreading, with rates becoming heavy for a 2-4 hour period in the city before mixing with sleet and eventually going over to rain by early Saturday evening.

North and west across northern Bucks, Montgomery and Chester counties and the Lehigh Valley, up to 4 inches can be expected with slightly higher amounts if snow banding takes place and the changeover is delayed. Extended and prolonged icing - in particular, sleet - could be a significant concern.

In Philadelphia and across southern New Jersey. we can expect 2+ inches. If intense banding takes place, we would be increasing the amounts.

Northern Delaware would be the same.

Will be updating again around the midnight hour, with a complete breakdown on Friday morning.

As the information comes in, you will get it first for any significant changes.

For now get ready for one BIG MESS on Saturday.

And check out my live chat on Philly.com at noon Saturday to guide you through the wintry mess and answer your questions concerning the storm.

John Bolaris

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3 p.m. update

Midday advisory

A winter storm is still on target to move in on Saturday. The Army/Navy game will be played in snow, with the possibility of sleet mixing in toward the latter half of the game. Kickoff temperature: 32 degrees. And look for wind to be a factor, out of the east at 15-25 mph.

WIth a wind chill of 22 expected, the Army/Navy layered look will definitely be needed!!

The latest computer data indicates a more juicy event.

The set-up

A storm system will move into the Ohio Valley early Saturday. As this storm weakens, a secondary coastal storm will take shape just off the northern Virginia shoreline. This second storm should intensify as it moves toward the southern New England coast by noon Sunday.

With a layer of Arctic air in place during the day on Saturday, snow will break out close to noon on Saturday - give or take an hour on either side. With a surge of warmer moist air riding over the cold air, snow intensity could become heavy for awhile even in the city before a changeover to sleet, then all rain by early evening.

Join John Bolaris at noon Saturday for live forecast updates and answers to your storm questions.

Northwest of the Blue Route, and across upper Bucks, northwest Montgomery and western Chester counties, and especially into the Lehigh Valley, a stripe of 2-4 inches of snow is possible with slightly higher amounts if the changeover is delayed by only a couple of hours. Right now I have changeover time north and west between 5-7 p.m.

Philadelphia: Right now forecasting a slushy couple of inches before changing over to rain.

Southern New Jersey and northern Delaware: Slushy inch or two, then a changeover to rain.

Timing: Snow arrives around noon time and quickly spreads, and snow rates will increase quickly for a brief 2 to 3-hour period which would lead to a quick burst of accumulations before changing over to rain between 4-6 p.m.

Accumulating snow time-frame: Noon to 4 p.m. city and most of interior southern New Jersey, little if anything for the shore. Accumulating snow for western Chester, Bucks, northwest Montgomery, and Lehigh Valley from 11 a.m.-5 p.m. Poconos: 4 inches-plus of snow, even with the changeover to sleet and freezing rain.

Right now also looking for pockets of freezing rain possible for a time across the Lehigh Valley during the evening hours.

Summary

Bulk of snow to fall Saturday afternoon, with changeover times by late in day and early evening.

Sunday storm pulls away, windy, dry and cold. Low 30s.

Will update you through out this latest event. and a live chat on Philly.com at noon Saturday to guide you through the wintry mess and answer your questions concerning the storm.

John Bolaris