Bolaris: Weekend storm not major, but will get messy

The Army Navy Game this Saturday will be played in snow and sleet, although nowhere near the Snow Blitz at Lincoln Financial Field last Sunday.

Latest computer models paint a significant, but NOT major storm this weekend as computer models are having a tough time determining where exactly a secondary coastal storm will form and just how intense it will be.

The other complicating factor: how much warmer ocean air will get involved in the higher levels of the atmosphere, and how long cold air will remain entrenched across the Delaware Valley.

My thinking now is that a storm will form along the Mid-Atlantic coast by Saturday evening, with a track just off the coast and strong intensification will NOT take place until the storm reaches a position off the southern New England coast.

For a major winter storm we would need what we call phasing of the Northern and Southern Jetstream. This would allow for explosive intensification, but at this time I just don't see this happening, sparing us from heavy snow. This storm looks to target New England and parts of New York State, north and east of New York City.

We are still a few computer runs away from a high confident forecast, but as of today I just don't see a major winter storm here in the Delaware Valley.

However with this being said, I still anticipate a significant mess of snow, sleet, freezing rain, and just plain rain to move in Saturday.

Here is the set-up:

Snow and some sleet moves in to the city on Saturday afternoon; yes, it should be snowing and possibly sleeting during the big Army/Navy game, with temperatures at 2 p.m. around 34 degrees.

The city, southern New Jersey and Northern Delaware might see a slushy accumulation before a changeover completely to rain by Saturday night.

North and west of the Blue Route, and especially into the Lehigh Valley, several inches of an icy wet snow might accumulate before a changeover to freezing rain. A complete changeover to rain remains in doubt, depending on cold air damming and the exact track and intensity of storm.

But strong easterly winds out ahead of the storm should push enough warm air inland for the changeover line to push north of the Blue Route. This will need to be watched closely on the day of the storm.

Saturday night will be messy, although my thinking now is for Philadelphia to be changing over to rain, and roadways should be mainly wet as surface temperatures should hover just above freezing.

Southern New Jersey and northern Delaware should be in the rain as well by Saturday night, though the timing is still difficult.

The northwest suburbs will have a prolonged period of snow and ice making for a very hazardous travel night across western Chester, Montgomery and Bucks counties, and all locations generally along or just north of the Blue Route.

ALL precipitation will be pulling away Sunday morning and windy, dry and cold conditions will return by Sunday afternoon with temps in the 30s.

This forecast will be tweaked and fine-tuned as we get closer to the event and the necessary changes will be posted right here on Philly.com.

For Thursday and Friday no worries, just dry and very cold with temps on Thursday never leaving the 20s.

John Bolaris